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<button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Errando%2C+M&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Errando%2C+M&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Errando%2C+M&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> <li> <a href="/search/?searchtype=author&query=Errando%2C+M&start=100" class="pagination-link " aria-label="Page 3" aria-current="page">3 </a> </li> </ul> </nav> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.16868">arXiv:2411.16868</a> <span> [<a href="https://arxiv.org/pdf/2411.16868">pdf</a>, <a href="https://arxiv.org/format/2411.16868">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> IXPE Observation of the Low-Synchrotron Peaked Blazar S4 0954+65 During An Optical-X-ray Flare </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kouch%2C+P+M">Pouya M. Kouch</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Fenu%2C+F">Francesco Fenu</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+H">Haocheng Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Boula%2C+S">Stella Boula</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Paraschos%2C+G+F">Georgios F. Paraschos</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Lindfors%2C+E">Elina Lindfors</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Krawczynski%2C+H">Henric Krawczynski</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Hu%2C+K">Kun Hu</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Cavazzuti%2C+E">Elisabetta Cavazzuti</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D">Dmitry Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Gourni%2C+A">Anastasia Gourni</a>, <a href="/search/astro-ph?searchtype=author&query=Kiehlmann%2C+S">Sebastian Kiehlmann</a>, <a href="/search/astro-ph?searchtype=author&query=Kourtidis%2C+A">Angelos Kourtidis</a>, <a href="/search/astro-ph?searchtype=author&query=Mandarakas%2C+N">Nikos Mandarakas</a>, <a href="/search/astro-ph?searchtype=author&query=Triantafyllou%2C+N">Nikolaos Triantafyllou</a>, <a href="/search/astro-ph?searchtype=author&query=Vervelaki%2C+A">Anna Vervelaki</a> , et al. (112 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2411.16868v1-abstract-short" style="display: inline;"> The X-ray polarization observations made possible with the Imaging X-ray Polarimetry Explorer (IXPE) offer new ways of probing high-energy emission processes in astrophysical jets from blazars. Here we report on the first X-ray polarization observation of the blazar S4 0954+65 in a high optical and X-ray state. During our multi-wavelength campaign on the source, we detected an optical flare whose… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.16868v1-abstract-full').style.display = 'inline'; document.getElementById('2411.16868v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.16868v1-abstract-full" style="display: none;"> The X-ray polarization observations made possible with the Imaging X-ray Polarimetry Explorer (IXPE) offer new ways of probing high-energy emission processes in astrophysical jets from blazars. Here we report on the first X-ray polarization observation of the blazar S4 0954+65 in a high optical and X-ray state. During our multi-wavelength campaign on the source, we detected an optical flare whose peak coincided with the peak of an X-ray flare. This optical-X-ray flare most likely took place in a feature moving along the parsec-scale jet, imaged at 43 GHz by the Very Long Baseline Array. The 43 GHz polarization angle of the moving component underwent a rotation near the time of the flare. In the optical band, prior to the IXPE observation, we measured the polarization angle to be aligned with the jet axis. In contrast, during the optical flare the optical polarization angle was perpendicular to the jet axis; after the flare, it reverted to being parallel to the jet axis. Due to the smooth behavior of the optical polarization angle during the flare, we favor shocks as the main acceleration mechanism. We also infer that the ambient magnetic field lines in the jet were parallel to the jet position angle. The average degree of optical polarization during the IXPE observation was (14.3$\pm$4.1)%. Despite the flare, we only detected an upper limit of 14% (at 3$蟽$ level) on the X-ray polarization degree; although a reasonable assumption on the X-ray polarization angle results in an upper limit of 8.8% ($3蟽$). We model the spectral energy distribution (SED) and spectral polarization distribution (SPD) of S4 0954+65 with leptonic (synchrotron self-Compton) and hadronic (proton and pair synchrotron) models. The constraints we obtain with our combined multi-wavelength polarization observations and SED modeling tentatively disfavor hadronic models for the X-ray emission in S4 0954+65. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.16868v1-abstract-full').style.display = 'none'; document.getElementById('2411.16868v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Submitted to A&A, 16 pages, 5 figures, and 7 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.13209">arXiv:2409.13209</a> <span> [<a href="https://arxiv.org/pdf/2409.13209">pdf</a>, <a href="https://arxiv.org/format/2409.13209">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> First operation of LArTPC in the stratosphere as an engineering GRAMS balloon flight (eGRAMS) </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Nakajima%2C+R">R. Nakajima</a>, <a href="/search/astro-ph?searchtype=author&query=Arai%2C+S">S. Arai</a>, <a href="/search/astro-ph?searchtype=author&query=Aoyama%2C+K">K. Aoyama</a>, <a href="/search/astro-ph?searchtype=author&query=Utsumi%2C+Y">Y. Utsumi</a>, <a href="/search/astro-ph?searchtype=author&query=Tamba%2C+T">T. Tamba</a>, <a href="/search/astro-ph?searchtype=author&query=Odaka%2C+H">H. Odaka</a>, <a href="/search/astro-ph?searchtype=author&query=Tanaka%2C+M">M. Tanaka</a>, <a href="/search/astro-ph?searchtype=author&query=Yorita%2C+K">K. Yorita</a>, <a href="/search/astro-ph?searchtype=author&query=Arai%2C+S">S. Arai</a>, <a href="/search/astro-ph?searchtype=author&query=Aramaki%2C+T">T. Aramaki</a>, <a href="/search/astro-ph?searchtype=author&query=Asaadi%2C+J">J. Asaadi</a>, <a href="/search/astro-ph?searchtype=author&query=Bamba%2C+A">A. Bamba</a>, <a href="/search/astro-ph?searchtype=author&query=Cannady%2C+N">N. Cannady</a>, <a href="/search/astro-ph?searchtype=author&query=Coppi%2C+P">P. Coppi</a>, <a href="/search/astro-ph?searchtype=author&query=De+Nolfo%2C+G">G. De Nolfo</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Fabris%2C+L">L. Fabris</a>, <a href="/search/astro-ph?searchtype=author&query=Fujiwara%2C+T">T. Fujiwara</a>, <a href="/search/astro-ph?searchtype=author&query=Fukazawa%2C+Y">Y. Fukazawa</a>, <a href="/search/astro-ph?searchtype=author&query=Ghosh%2C+P">P. Ghosh</a>, <a href="/search/astro-ph?searchtype=author&query=Hagino%2C+K">K. Hagino</a>, <a href="/search/astro-ph?searchtype=author&query=Hakamata%2C+T">T. Hakamata</a>, <a href="/search/astro-ph?searchtype=author&query=Hijikata%2C+U">U. Hijikata</a>, <a href="/search/astro-ph?searchtype=author&query=Hiroshima%2C+N">N. Hiroshima</a>, <a href="/search/astro-ph?searchtype=author&query=Ichihashi%2C+M">M. Ichihashi</a> , et al. (39 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2409.13209v2-abstract-short" style="display: inline;"> GRAMS (Gamma-Ray and AntiMatter Survey) is a next-generation balloon/satellite experiment utilizing a LArTPC (Liquid Argon Time Projection Chamber), to simultaneously target astrophysical observations of cosmic MeV gamma-rays and conduct an indirect dark matter search using antimatter. While LArTPCs are widely used in particle physics experiments, they have never been operated at balloon altitudes… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.13209v2-abstract-full').style.display = 'inline'; document.getElementById('2409.13209v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.13209v2-abstract-full" style="display: none;"> GRAMS (Gamma-Ray and AntiMatter Survey) is a next-generation balloon/satellite experiment utilizing a LArTPC (Liquid Argon Time Projection Chamber), to simultaneously target astrophysical observations of cosmic MeV gamma-rays and conduct an indirect dark matter search using antimatter. While LArTPCs are widely used in particle physics experiments, they have never been operated at balloon altitudes. An engineering balloon flight with a small-scale LArTPC (eGRAMS) was conducted on July 27th, 2023, to establish a system for safely operating a LArTPC at balloon altitudes and to obtain cosmic-ray data from the LArTPC. The flight was launched from the Japan Aerospace Exploration Agency's (JAXA) Taiki Aerospace Research Field in Hokkaido, Japan. The total flight duration was 3 hours and 12 minutes, including a level flight of 44 minutes at a maximum altitude of 28.9 km. The flight system was landed on the sea and successfully recovered. The LArTPC was successfully operated throughout the flight, and about 0.5 million events of the cosmic-ray data including muons, protons, and Compton scattering gamma-ray candidates, were collected. This pioneering flight demonstrates the feasibility of operating a LArTPC in high-altitude environments, paving the way for future GRAMS missions and advancing our capabilities in MeV gamma-ray astronomy and dark matter research. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.13209v2-abstract-full').style.display = 'none'; document.getElementById('2409.13209v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.16518">arXiv:2407.16518</a> <span> [<a href="https://arxiv.org/pdf/2407.16518">pdf</a>, <a href="https://arxiv.org/format/2407.16518">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> </div> </div> <p class="title is-5 mathjax"> An indirect search for dark matter with a combined analysis of dwarf spheroidal galaxies from VERITAS </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Acharyya%2C+A">A. Acharyya</a>, <a href="/search/astro-ph?searchtype=author&query=Adams%2C+C+B">C. B. Adams</a>, <a href="/search/astro-ph?searchtype=author&query=Bangale%2C+P">P. Bangale</a>, <a href="/search/astro-ph?searchtype=author&query=Bartkoske%2C+J+T">J. T. Bartkoske</a>, <a href="/search/astro-ph?searchtype=author&query=Batista%2C+P">P. Batista</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Christiansen%2C+J+L">J. L. Christiansen</a>, <a href="/search/astro-ph?searchtype=author&query=Chromey%2C+A+J">A. J. Chromey</a>, <a href="/search/astro-ph?searchtype=author&query=Duerr%2C+A">A. Duerr</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">A. Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Foote%2C+G+M">G. M. Foote</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">A. Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Hanlon%2C+W">W. Hanlon</a>, <a href="/search/astro-ph?searchtype=author&query=Hanna%2C+D">D. Hanna</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">O. Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=Hinrichs%2C+C+E">C. E. Hinrichs</a>, <a href="/search/astro-ph?searchtype=author&query=Holder%2C+J">J. Holder</a>, <a href="/search/astro-ph?searchtype=author&query=Humensky%2C+T+B">T. B. Humensky</a>, <a href="/search/astro-ph?searchtype=author&query=Jin%2C+W">W. Jin</a>, <a href="/search/astro-ph?searchtype=author&query=Johnson%2C+M+N">M. N. Johnson</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">P. Kaaret</a>, <a href="/search/astro-ph?searchtype=author&query=Kertzman%2C+M">M. Kertzman</a> , et al. (37 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.16518v2-abstract-short" style="display: inline;"> Understanding the nature and identity of dark matter is a key goal in the physics community. In the case that TeV-scale dark matter particles decay or annihilate into standard model particles, very-high-energy (VHE) gamma rays (greater than 100 GeV) will be present in the final state. The Very Energetic Radiation Imaging Telescope Array System (VERITAS) is an imaging atmospheric Cherenkov telescop… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.16518v2-abstract-full').style.display = 'inline'; document.getElementById('2407.16518v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.16518v2-abstract-full" style="display: none;"> Understanding the nature and identity of dark matter is a key goal in the physics community. In the case that TeV-scale dark matter particles decay or annihilate into standard model particles, very-high-energy (VHE) gamma rays (greater than 100 GeV) will be present in the final state. The Very Energetic Radiation Imaging Telescope Array System (VERITAS) is an imaging atmospheric Cherenkov telescope array that can indirectly detect VHE gamma rays in an energy range of 100 GeV to > 30 TeV. Dwarf spheroidal galaxies (dSphs) are ideal candidates in the search for dark matter due to their high dark matter content, high mass-to-light ratios, and their low gamma-ray fluxes from astrophysical processes. This study uses a legacy data set of 638 hours collected on 17 dSphs, built over 11 years with an observing strategy optimized according to the dark matter content of the targets. The study addresses a broad dark matter particle mass range, extending from 200 GeV to 30 PeV. In the absence of a detection, we set the upper limits on the dark matter velocity-weighted annihilation cross section. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.16518v2-abstract-full').style.display = 'none'; document.getElementById('2407.16518v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">18 pages, 7 figures, 3 tables, accepted in PRD</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.11848">arXiv:2407.11848</a> <span> [<a href="https://arxiv.org/pdf/2407.11848">pdf</a>, <a href="https://arxiv.org/format/2407.11848">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> </div> <p class="title is-5 mathjax"> A multi-wavelength study to decipher the 2017 flare of the blazar OJ 287 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Acharyya%2C+A">A. Acharyya</a>, <a href="/search/astro-ph?searchtype=author&query=Adams%2C+C+B">C. B. Adams</a>, <a href="/search/astro-ph?searchtype=author&query=Archer%2C+A">A. Archer</a>, <a href="/search/astro-ph?searchtype=author&query=Bangale%2C+P">P. Bangale</a>, <a href="/search/astro-ph?searchtype=author&query=Bartkoske%2C+J+T">J. T. Bartkoske</a>, <a href="/search/astro-ph?searchtype=author&query=Batista%2C+P">P. Batista</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Brill%2C+A">A. Brill</a>, <a href="/search/astro-ph?searchtype=author&query=Caldwell%2C+J+P">J. P. Caldwell</a>, <a href="/search/astro-ph?searchtype=author&query=Carini%2C+M">M. Carini</a>, <a href="/search/astro-ph?searchtype=author&query=Christiansen%2C+J+L">J. L. Christiansen</a>, <a href="/search/astro-ph?searchtype=author&query=Chromey%2C+A+J">A. J. Chromey</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">A. Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+J+P">J. P. Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Foote%2C+J">J. Foote</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">A. Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Gallagher%2C+G">G. Gallagher</a>, <a href="/search/astro-ph?searchtype=author&query=Hanlon%2C+W">W. Hanlon</a>, <a href="/search/astro-ph?searchtype=author&query=Hanna%2C+D">D. Hanna</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">O. Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=Hinrichs%2C+C+E">C. E. Hinrichs</a>, <a href="/search/astro-ph?searchtype=author&query=Hoang%2C+J">J. Hoang</a> , et al. (49 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.11848v3-abstract-short" style="display: inline;"> In February 2017, the blazar OJ~287 underwent a period of intense multiwavelength activity. It reached a new historic peak in the soft X-ray (0.3-10 keV) band, as measured by Swift-XRT. This event coincides with a very-high-energy (VHE) $纬$-ray outburst that led VERITAS to detect emission above 100 GeV, with a detection significance of $10蟽$ (from 2016 December 9 to 2017 March 31). The time-averag… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.11848v3-abstract-full').style.display = 'inline'; document.getElementById('2407.11848v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.11848v3-abstract-full" style="display: none;"> In February 2017, the blazar OJ~287 underwent a period of intense multiwavelength activity. It reached a new historic peak in the soft X-ray (0.3-10 keV) band, as measured by Swift-XRT. This event coincides with a very-high-energy (VHE) $纬$-ray outburst that led VERITAS to detect emission above 100 GeV, with a detection significance of $10蟽$ (from 2016 December 9 to 2017 March 31). The time-averaged VHE $纬$-ray spectrum was consistent with a soft power law ($螕= -3.81 \pm 0.26$) and an integral flux corresponding to $\sim2.4\%$ that of the Crab Nebula above the same energy. Contemporaneous data from multiple instruments across the electromagnetic spectrum reveal complex flaring behavior, primarily in the soft X-ray and VHE bands. To investigate the possible origin of such an event, our study focuses on three distinct activity states: before, during, and after the February 2017 peak. The spectral energy distributions during these periods suggest the presence of at least two non-thermal emission zones, with the more compact one responsible for the observed flare. Broadband modeling results and observations of a new radio knot in the jet of OJ~287 in 2017 are consistent with a flare originating from a strong recollimation shock outside the radio core. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.11848v3-abstract-full').style.display = 'none'; document.getElementById('2407.11848v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 16 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages, 7 figures, accepted for publication in The Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.11128">arXiv:2407.11128</a> <span> [<a href="https://arxiv.org/pdf/2407.11128">pdf</a>, <a href="https://arxiv.org/format/2407.11128">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> </div> <p class="title is-5 mathjax"> X-ray and multiwavelength polarization of Mrk 501 from 2022 to 2023 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Chen%2C+C+J">Chien-Ting J. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Ehlert%2C+S+R">Steven R. Ehlert</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Wu%2C+K">Kinwah Wu</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Mizuno%2C+T">Tsunefumi Mizuno</a>, <a href="/search/astro-ph?searchtype=author&query=Kouch%2C+P+M">Pouya M. Kouch</a>, <a href="/search/astro-ph?searchtype=author&query=Lindfors%2C+E">Elina Lindfors</a>, <a href="/search/astro-ph?searchtype=author&query=Borman%2C+G+A">George A. Borman</a>, <a href="/search/astro-ph?searchtype=author&query=Grishina%2C+T+S">Tatiana S. Grishina</a>, <a href="/search/astro-ph?searchtype=author&query=Kopatskaya%2C+E+N">Evgenia N. Kopatskaya</a>, <a href="/search/astro-ph?searchtype=author&query=Larionova%2C+E+G">Elena G. Larionova</a>, <a href="/search/astro-ph?searchtype=author&query=Morozova%2C+D+A">Daria A. Morozova</a>, <a href="/search/astro-ph?searchtype=author&query=Savchenko%2C+S+S">Sergey S. Savchenko</a>, <a href="/search/astro-ph?searchtype=author&query=Troitsky%2C+I+S">Ivan S. Troitsky</a>, <a href="/search/astro-ph?searchtype=author&query=Troitskaya%2C+Y+V">Yulia V. Troitskaya</a> , et al. (121 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.11128v1-abstract-short" style="display: inline;"> We present multiwavelength polarization measurements of the luminous blazar Mrk~501 over a 14-month period. The 2--8 keV X-ray polarization was measured with the Imaging X-ray Polarimetry Explorer (IXPE) with six 100-ks observations spanning from 2022 March to 2023 April. Each IXPE observation was accompanied by simultaneous X-ray data from NuSTAR, Swift/XRT, and/or XMM-Newton. Complementary optic… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.11128v1-abstract-full').style.display = 'inline'; document.getElementById('2407.11128v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.11128v1-abstract-full" style="display: none;"> We present multiwavelength polarization measurements of the luminous blazar Mrk~501 over a 14-month period. The 2--8 keV X-ray polarization was measured with the Imaging X-ray Polarimetry Explorer (IXPE) with six 100-ks observations spanning from 2022 March to 2023 April. Each IXPE observation was accompanied by simultaneous X-ray data from NuSTAR, Swift/XRT, and/or XMM-Newton. Complementary optical-infrared polarization measurements were also available in the B, V, R, I, and J bands, as were radio polarization measurements from 4.85 GHz to 225.5 GHz. Among the first five IXPE observations, we did not find significant variability in the X-ray polarization degree and angle with IXPE. However, the most recent sixth observation found an elevated polarization degree at $>3蟽$ above the average of the other five observations. The optical and radio measurements show no apparent correlations with the X-ray polarization properties. Throughout the six IXPE observations, the X-ray polarization degree remained higher than, or similar to, the R-band optical polarization degree, which remained higher than the radio value. This is consistent with the energy-stratified shock scenario proposed to explain the first two IXPE observations, in which the polarized X-ray, optical, and radio emission arises from different regions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.11128v1-abstract-full').style.display = 'none'; document.getElementById('2407.11128v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.07635">arXiv:2406.07635</a> <span> [<a href="https://arxiv.org/pdf/2406.07635">pdf</a>, <a href="https://arxiv.org/format/2406.07635">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> A gamma-ray flare from TXS 1508+572: characterizing the jet of a $z=4.31$ blazar in the early Universe </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Gokus%2C+A">Andrea Gokus</a>, <a href="/search/astro-ph?searchtype=author&query=B%C3%B6ttcher%2C+M">Markus B枚ttcher</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Kreter%2C+M">Michael Kreter</a>, <a href="/search/astro-ph?searchtype=author&query=He%C3%9Fd%C3%B6rfer%2C+J">Jonas He脽d枚rfer</a>, <a href="/search/astro-ph?searchtype=author&query=Eppel%2C+F">Florian Eppel</a>, <a href="/search/astro-ph?searchtype=author&query=Kadler%2C+M">Matthias Kadler</a>, <a href="/search/astro-ph?searchtype=author&query=Smith%2C+P+S">Paul S. Smith</a>, <a href="/search/astro-ph?searchtype=author&query=Benke%2C+P">Petra Benke</a>, <a href="/search/astro-ph?searchtype=author&query=Gurvits%2C+L+I">Leonid I. Gurvits</a>, <a href="/search/astro-ph?searchtype=author&query=Kraus%2C+A">Alex Kraus</a>, <a href="/search/astro-ph?searchtype=author&query=Lisakov%2C+M">Mikhail Lisakov</a>, <a href="/search/astro-ph?searchtype=author&query=McBride%2C+F">Felicia McBride</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">Eduardo Ros</a>, <a href="/search/astro-ph?searchtype=author&query=R%C3%B6sch%2C+F">Florian R枚sch</a>, <a href="/search/astro-ph?searchtype=author&query=Wilms%2C+J">J枚rn Wilms</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2406.07635v2-abstract-short" style="display: inline;"> Blazars can be detected from very large distances due to their high luminosity. However, the detection of $纬$-ray emission of blazars beyond $z=3$ has only been confirmed for a small number of sources. Such observations probe the growth of supermassive black holes close to the peak of star formation in the history of galaxy evolution. As a result from a continuous monitoring of a sample of 80… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.07635v2-abstract-full').style.display = 'inline'; document.getElementById('2406.07635v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.07635v2-abstract-full" style="display: none;"> Blazars can be detected from very large distances due to their high luminosity. However, the detection of $纬$-ray emission of blazars beyond $z=3$ has only been confirmed for a small number of sources. Such observations probe the growth of supermassive black holes close to the peak of star formation in the history of galaxy evolution. As a result from a continuous monitoring of a sample of 80 $z>3$ blazars with Fermi-LAT, we present the first detection of a $纬$-ray flare from the $z=4.31$ blazar TXS 1508+572. This source showed high $纬$-ray activity from February to August 2022, reaching a peak luminosity comparable to the most luminous flares ever detected with Fermi -LAT. We conducted a multiwavelength observing campaign involving XMM-Newton, Swift, the Effelsberg 100-m radio telescope and the Very Long Baseline Array. In addition, we make use of the monitoring programs by the Zwicky Transient Facility and NEOWISE at optical and infrared wavelengths, respectively. We find that the source is particularly variable in the infrared band on daily time scales. The spectral energy distribution collected during our campaign is well described by a one-zone leptonic model, with the $纬$-ray flare originating from an increase of external Compton emission as a result of a fresh injection of accelerated electrons. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.07635v2-abstract-full').style.display = 'none'; document.getElementById('2406.07635v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 8 figures; accepted by ApJ on July 30 - Initial version on arXiv is the submitted one</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.01693">arXiv:2406.01693</a> <span> [<a href="https://arxiv.org/pdf/2406.01693">pdf</a>, <a href="https://arxiv.org/format/2406.01693">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202449166">10.1051/0004-6361/202449166 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> IXPE observation of PKS 2155-304 reveals the most highly polarized blazar </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kouch%2C+P+M">Pouya M. Kouch</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Tavecchio%2C+F">Fabrizio Tavecchio</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Ehlert%2C+S+R">Steven R. Ehlert</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Madejski%2C+G+M">Grzegorz M. Madejski</a>, <a href="/search/astro-ph?searchtype=author&query=Romani%2C+R+W">Roger W. Romani</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Lindfors%2C+E">Elina Lindfors</a>, <a href="/search/astro-ph?searchtype=author&query=Nilsson%2C+K">Kari Nilsson</a>, <a href="/search/astro-ph?searchtype=author&query=Toppari%2C+E">Ella Toppari</a>, <a href="/search/astro-ph?searchtype=author&query=Potter%2C+S+B">Stephen B. Potter</a>, <a href="/search/astro-ph?searchtype=author&query=Imazawa%2C+R">Ryo Imazawa</a>, <a href="/search/astro-ph?searchtype=author&query=Sasada%2C+M">Mahito Sasada</a>, <a href="/search/astro-ph?searchtype=author&query=Fukazawa%2C+Y">Yasushi Fukazawa</a>, <a href="/search/astro-ph?searchtype=author&query=Kawabata%2C+K+S">Koji S. Kawabata</a>, <a href="/search/astro-ph?searchtype=author&query=Uemura%2C+M">Makoto Uemura</a>, <a href="/search/astro-ph?searchtype=author&query=Mizuno%2C+T">Tsunefumi Mizuno</a>, <a href="/search/astro-ph?searchtype=author&query=Nakaoka%2C+T">Tatsuya Nakaoka</a> , et al. (111 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2406.01693v1-abstract-short" style="display: inline;"> We report the X-ray polarization properties of the high-synchrotron-peaked (HSP) blazar PKS 2155$-$304 based on observations with the Imaging X-ray Polarimetry Explorer (IXPE). We observed the source between Oct 27 and Nov 7, 2023. We also conducted an extensive contemporaneous multiwavelength (MW) campaign. We find that during the first half ($T_1$) of the IXPE pointing, the source exhibited the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.01693v1-abstract-full').style.display = 'inline'; document.getElementById('2406.01693v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.01693v1-abstract-full" style="display: none;"> We report the X-ray polarization properties of the high-synchrotron-peaked (HSP) blazar PKS 2155$-$304 based on observations with the Imaging X-ray Polarimetry Explorer (IXPE). We observed the source between Oct 27 and Nov 7, 2023. We also conducted an extensive contemporaneous multiwavelength (MW) campaign. We find that during the first half ($T_1$) of the IXPE pointing, the source exhibited the highest X-ray polarization degree detected for an HSP blazar thus far, (30.7$\pm$2.0)%, which dropped to (15.3$\pm$2.1)% during the second half ($T_2$). The X-ray polarization angle remained stable during the IXPE pointing at 129.4$^\circ$$\pm$1.8$^\circ$ and 125.4$^\circ$$\pm$3.9$^\circ$ during $T_1$ and $T_2$, respectively. Meanwhile, the optical polarization degree remained stable during the IXPE pointing, with average host-galaxy-corrected values of (4.3$\pm$0.7)% and (3.8$\pm$0.9)% during the $T_1$ and $T_2$, respectively. During the IXPE pointing, the optical polarization angle changed achromatically from $\sim$140$^\circ$ to $\sim$90$^\circ$ and back to $\sim$130$^\circ$. Despite several attempts, we only detected (99.7% conf.) the radio polarization once (during $T_2$, at 225.5 GHz): with degree (1.7$\pm$0.4)% and angle 112.5$^\circ$$\pm$5.5$^\circ$. The direction of the broad pc-scale jet is rather ambiguous and has been found to point to the east and south at different epochs; however, on larger scales (> 1.5 pc) the jet points toward the southeast ($\sim$135$^\circ$), similar to all of the MW polarization angles. Moreover, the X-ray to optical polarization degree ratios of $\sim$7 and $\sim$4 during $T_1$ and $T_2$, respectively, are similar to previous IXPE results for several HSP blazars. These findings, combined with the lack of correlation of temporal variability between the MW polarization properties, agree with an energy-stratified shock-acceleration scenario in HSP blazars. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.01693v1-abstract-full').style.display = 'none'; document.getElementById('2406.01693v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">17 pages, 10 figures, 4 tables, Accepted for publication in A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 689, A119 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.04857">arXiv:2403.04857</a> <span> [<a href="https://arxiv.org/pdf/2403.04857">pdf</a>, <a href="https://arxiv.org/format/2403.04857">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1475-7516/2024/07/047">10.1088/1475-7516/2024/07/047 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Dark Matter Line Searches with the Cherenkov Telescope Array </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Abe%2C+S">S. Abe</a>, <a href="/search/astro-ph?searchtype=author&query=Abhir%2C+J">J. Abhir</a>, <a href="/search/astro-ph?searchtype=author&query=Abhishek%2C+A">A. Abhishek</a>, <a href="/search/astro-ph?searchtype=author&query=Acero%2C+F">F. Acero</a>, <a href="/search/astro-ph?searchtype=author&query=Acharyya%2C+A">A. Acharyya</a>, <a href="/search/astro-ph?searchtype=author&query=Adam%2C+R">R. Adam</a>, <a href="/search/astro-ph?searchtype=author&query=Aguasca-Cabot%2C+A">A. Aguasca-Cabot</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">I. Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Aguirre-Santaella%2C+A">A. Aguirre-Santaella</a>, <a href="/search/astro-ph?searchtype=author&query=Alfaro%2C+J">J. Alfaro</a>, <a href="/search/astro-ph?searchtype=author&query=Alfaro%2C+R">R. Alfaro</a>, <a href="/search/astro-ph?searchtype=author&query=Alvarez-Crespo%2C+N">N. Alvarez-Crespo</a>, <a href="/search/astro-ph?searchtype=author&query=Batista%2C+R+A">R. Alves Batista</a>, <a href="/search/astro-ph?searchtype=author&query=Amans%2C+J+-">J. -P. Amans</a>, <a href="/search/astro-ph?searchtype=author&query=Amato%2C+E">E. Amato</a>, <a href="/search/astro-ph?searchtype=author&query=Ambrosi%2C+G">G. Ambrosi</a>, <a href="/search/astro-ph?searchtype=author&query=Angel%2C+L">L. Angel</a>, <a href="/search/astro-ph?searchtype=author&query=Aramo%2C+C">C. Aramo</a>, <a href="/search/astro-ph?searchtype=author&query=Arcaro%2C+C">C. Arcaro</a>, <a href="/search/astro-ph?searchtype=author&query=Arnesen%2C+T+T+H">T. T. H. Arnesen</a>, <a href="/search/astro-ph?searchtype=author&query=Arrabito%2C+L">L. Arrabito</a>, <a href="/search/astro-ph?searchtype=author&query=Asano%2C+K">K. Asano</a>, <a href="/search/astro-ph?searchtype=author&query=Ascasibar%2C+Y">Y. Ascasibar</a>, <a href="/search/astro-ph?searchtype=author&query=Aschersleben%2C+J">J. Aschersleben</a>, <a href="/search/astro-ph?searchtype=author&query=Ashkar%2C+H">H. Ashkar</a> , et al. (540 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2403.04857v2-abstract-short" style="display: inline;"> Monochromatic gamma-ray signals constitute a potential smoking gun signature for annihilating or decaying dark matter particles that could relatively easily be distinguished from astrophysical or instrumental backgrounds. We provide an updated assessment of the sensitivity of the Cherenkov Telescope Array (CTA) to such signals, based on observations of the Galactic centre region as well as of sele… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.04857v2-abstract-full').style.display = 'inline'; document.getElementById('2403.04857v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.04857v2-abstract-full" style="display: none;"> Monochromatic gamma-ray signals constitute a potential smoking gun signature for annihilating or decaying dark matter particles that could relatively easily be distinguished from astrophysical or instrumental backgrounds. We provide an updated assessment of the sensitivity of the Cherenkov Telescope Array (CTA) to such signals, based on observations of the Galactic centre region as well as of selected dwarf spheroidal galaxies. We find that current limits and detection prospects for dark matter masses above 300 GeV will be significantly improved, by up to an order of magnitude in the multi-TeV range. This demonstrates that CTA will set a new standard for gamma-ray astronomy also in this respect, as the world's largest and most sensitive high-energy gamma-ray observatory, in particular due to its exquisite energy resolution at TeV energies and the adopted observational strategy focussing on regions with large dark matter densities. Throughout our analysis, we use up-to-date instrument response functions, and we thoroughly model the effect of instrumental systematic uncertainties in our statistical treatment. We further present results for other potential signatures with sharp spectral features, e.g.~box-shaped spectra, that would likewise very clearly point to a particle dark matter origin. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.04857v2-abstract-full').style.display = 'none'; document.getElementById('2403.04857v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 7 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">44 pages JCAP style (excluding author list and references), 19 figures; minor changes to match published version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> JCAP 07 (2024) 047 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.04460">arXiv:2401.04460</a> <span> [<a href="https://arxiv.org/pdf/2401.04460">pdf</a>, <a href="https://arxiv.org/format/2401.04460">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1007/978-981-16-4544-0_61-1">10.1007/978-981-16-4544-0_61-1 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> How to detect gamma-rays from ground: an introduction to the detection concepts </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Saito%2C+T">Takayuki Saito</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2401.04460v1-abstract-short" style="display: inline;"> Indirect detection of gamma rays with ground-based observatories is currently the most sensitive experimental approach to characterize the gamma-ray sky at energies $>0.1$\,TeV. Ground-based detection of gamma-rays relies on the electromagnetic showers that gamma rays initiate in the Earth's atmosphere. In this chapter we will review the properties of electromagnetic air showers as well as the dif… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.04460v1-abstract-full').style.display = 'inline'; document.getElementById('2401.04460v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.04460v1-abstract-full" style="display: none;"> Indirect detection of gamma rays with ground-based observatories is currently the most sensitive experimental approach to characterize the gamma-ray sky at energies $>0.1$\,TeV. Ground-based detection of gamma-rays relies on the electromagnetic showers that gamma rays initiate in the Earth's atmosphere. In this chapter we will review the properties of electromagnetic air showers as well as the differences with respect to cosmic-ray showers that enable the rejection of the cosmic ray background. The experimental techniques that have been developed for ground-based detection of gamma rays will be introduced. These fall onto three main categories: air shower particle detectors, sampling Cherenkov arrays, and imaging atmospheric Cherenkov telescopes. Hybrid concepts as well as other experimental approaches are also discussed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.04460v1-abstract-full').style.display = 'none'; document.getElementById('2401.04460v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">24 pages, 11 figures, invited chapter in Handbook of X-ray and Gamma-ray Astrophysics (eds. Cosimo Bambi and Andrea Santangelo)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Handbook of X-ray and Gamma-ray Astrophysics (eds. C. Bambi, A. Santangelo), Springer Singapore (2023), id. 144 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.04420">arXiv:2401.04420</a> <span> [<a href="https://arxiv.org/pdf/2401.04420">pdf</a>, <a href="https://arxiv.org/format/2401.04420">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ad1ce4">10.3847/1538-4357/ad1ce4 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Detection of X-ray Polarization from the Blazar 1ES 1959+650 with the Imaging X-ray Polarimetry Explorer </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Peirson%2C+A+L">Abel Lawrence Peirson</a>, <a href="/search/astro-ph?searchtype=author&query=Perri%2C+M">Matteo Perri</a>, <a href="/search/astro-ph?searchtype=author&query=Puccetti%2C+S">Simonetta Puccetti</a>, <a href="/search/astro-ph?searchtype=author&query=Rabinowitz%2C+P+L">Pazit L. Rabinowitz</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Savchenko%2C+S+S">Sergey S. Savchenko</a>, <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D">Dmitry Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Bourbah%2C+I+G">Ioakeim G. Bourbah</a>, <a href="/search/astro-ph?searchtype=author&query=Kiehlmann%2C+S">Sebastian Kiehlmann</a>, <a href="/search/astro-ph?searchtype=author&query=Kontopodis%2C+E">Evangelos Kontopodis</a>, <a href="/search/astro-ph?searchtype=author&query=Mandarakas%2C+N">Nikos Mandarakas</a>, <a href="/search/astro-ph?searchtype=author&query=Romanopoulos%2C+S">Stylianos Romanopoulos</a>, <a href="/search/astro-ph?searchtype=author&query=Skalidis%2C+R">Raphael Skalidis</a>, <a href="/search/astro-ph?searchtype=author&query=Vervelaki%2C+A">Anna Vervelaki</a>, <a href="/search/astro-ph?searchtype=author&query=Aceituno%2C+F+J">Francisco Jos茅 Aceituno</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardos%2C+M+I">Maria I. Bernardos</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">Giacomo Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Casanova%2C+V">V铆ctor Casanova</a> , et al. (121 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2401.04420v1-abstract-short" style="display: inline;"> Observations of linear polarization in the 2-8 keV energy range with the Imaging X-ray Polarimetry Explorer (IXPE) explore the magnetic field geometry and dynamics of the regions generating non-thermal radiation in relativistic jets of blazars. These jets, particularly in blazars whose spectral energy distribution peaks at X-ray energies, emit X-rays via synchrotron radiation from high-energy part… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.04420v1-abstract-full').style.display = 'inline'; document.getElementById('2401.04420v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.04420v1-abstract-full" style="display: none;"> Observations of linear polarization in the 2-8 keV energy range with the Imaging X-ray Polarimetry Explorer (IXPE) explore the magnetic field geometry and dynamics of the regions generating non-thermal radiation in relativistic jets of blazars. These jets, particularly in blazars whose spectral energy distribution peaks at X-ray energies, emit X-rays via synchrotron radiation from high-energy particles within the jet. IXPE observations of the X-ray selected BL Lac-type blazar 1ES 1959+650 in 2022 May 3-4 showed a significant linear polarization degree of $螤_\mathrm{x} = 8.0\% \pm 2.3\%$ at an electric-vector position angle $蠄_\mathrm{x} = 123^\circ \pm 8^\circ$. However, in 2022 June 9-12, only an upper limit of $螤_\mathrm{x} \leq 5.1\%$ could be derived (at the 99% confidence level). The degree of optical polarization at that time $螤_\mathrm{O} \sim 5\%$ is comparable to the X-ray measurement. We investigate possible scenarios for these findings, including temporal and geometrical depolarization effects. Unlike some other X-ray selected BL Lac objects, there is no significant chromatic dependence of the measured polarization in 1ES 1959+650, and its low X-ray polarization may be attributed to turbulence in the jet flow with dynamical timescales shorter than 1 day. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.04420v1-abstract-full').style.display = 'none'; document.getElementById('2401.04420v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">16 pages, 4 figures, accepted for publication in The Astrophysical Journal</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> The Astrophysical Journal, 963 (2024) 5 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.07774">arXiv:2312.07774</a> <span>  </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> VERITAS contributions to the 38th International Cosmic Ray Conference </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Acharyya%2C+A">A. Acharyya</a>, <a href="/search/astro-ph?searchtype=author&query=Adams%2C+C+B">C. B. Adams</a>, <a href="/search/astro-ph?searchtype=author&query=Archer%2C+A">A. Archer</a>, <a href="/search/astro-ph?searchtype=author&query=Bangale%2C+P">P. Bangale</a>, <a href="/search/astro-ph?searchtype=author&query=Bartkoske%2C+J+T">J. T. Bartkoske</a>, <a href="/search/astro-ph?searchtype=author&query=Batista%2C+P">P. Batista</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Christiansen%2C+J+L">J. L. Christiansen</a>, <a href="/search/astro-ph?searchtype=author&query=Chromey%2C+A+J">A. J. Chromey</a>, <a href="/search/astro-ph?searchtype=author&query=Duerr%2C+A">A. Duerr</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Foote%2C+G+M">G. M. Foote</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">A. Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Hanlon%2C+W">W. Hanlon</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">O. Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=Hinrichs%2C+C+E">C. E. Hinrichs</a>, <a href="/search/astro-ph?searchtype=author&query=Hoang%2C+J">J. Hoang</a>, <a href="/search/astro-ph?searchtype=author&query=Holder%2C+J">J. Holder</a>, <a href="/search/astro-ph?searchtype=author&query=Hughes%2C+Z">Z. Hughes</a>, <a href="/search/astro-ph?searchtype=author&query=Humensky%2C+T+B">T. B. Humensky</a>, <a href="/search/astro-ph?searchtype=author&query=Jin%2C+W">W. Jin</a>, <a href="/search/astro-ph?searchtype=author&query=Johnson%2C+M+N">M. N. Johnson</a>, <a href="/search/astro-ph?searchtype=author&query=Kertzman%2C+M">M. Kertzman</a> , et al. (39 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2312.07774v1-abstract-short" style="display: inline;"> Compilation of papers presented by the VERITAS Collaboration at the 38th International Cosmic Ray Conference (ICRC), held July 26 through August 3, 2023 in Nagoya, Japan. </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.07774v1-abstract-full" style="display: none;"> Compilation of papers presented by the VERITAS Collaboration at the 38th International Cosmic Ray Conference (ICRC), held July 26 through August 3, 2023 in Nagoya, Japan. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.07774v1-abstract-full').style.display = 'none'; document.getElementById('2312.07774v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">html page. ICRC 2023, Nagoya, Japan</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2311.04801">arXiv:2311.04801</a> <span> [<a href="https://arxiv.org/pdf/2311.04801">pdf</a>, <a href="https://arxiv.org/format/2311.04801">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> </div> <p class="title is-5 mathjax"> The High Energy X-ray Probe (HEX-P): the most powerful jets through the lens of a superb X-ray eye </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Marcotulli%2C+L">Lea Marcotulli</a>, <a href="/search/astro-ph?searchtype=author&query=Ajello%2C+M">Marco Ajello</a>, <a href="/search/astro-ph?searchtype=author&query=B%C3%B6ttcher%2C+M">Markus B枚ttcher</a>, <a href="/search/astro-ph?searchtype=author&query=Coppi%2C+P">Paolo Coppi</a>, <a href="/search/astro-ph?searchtype=author&query=Costamante%2C+L">Luigi Costamante</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Garc%C3%ADa%2C+J+A">Javier A. Garc铆a</a>, <a href="/search/astro-ph?searchtype=author&query=Gokus%2C+A">Andrea Gokus</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Madejski%2C+G">Greg Madejski</a>, <a href="/search/astro-ph?searchtype=author&query=Madsen%2C+K">Kristin Madsen</a>, <a href="/search/astro-ph?searchtype=author&query=Moretti%2C+A">Alberto Moretti</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=McBride%2C+F">Felicia McBride</a>, <a href="/search/astro-ph?searchtype=author&query=Petropoulou%2C+M">Maria Petropoulou</a>, <a href="/search/astro-ph?searchtype=author&query=Rani%2C+B">Bindu Rani</a>, <a href="/search/astro-ph?searchtype=author&query=Sbarrato%2C+T">Tullia Sbarrato</a>, <a href="/search/astro-ph?searchtype=author&query=Stern%2C+D">Daniel Stern</a>, <a href="/search/astro-ph?searchtype=author&query=Vasilopoulos%2C+G">Georgios Vasilopoulos</a>, <a href="/search/astro-ph?searchtype=author&query=Zacharias%2C+M">Michael Zacharias</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+H">Haocheng Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Collaboration%2C+t+H">the HEX-P Collaboration</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2311.04801v1-abstract-short" style="display: inline;"> A fraction of the active supermassive black holes at the centers of galaxies in our Universe are capable of launching extreme kiloparsec-long relativistic jets. These jets are known multiband (radio to $纬$-ray) and multimessenger (neutrino) emitters, and some of them have been monitored over several decades at all accessible wavelengths. However, many open questions remain unanswered about the pro… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.04801v1-abstract-full').style.display = 'inline'; document.getElementById('2311.04801v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.04801v1-abstract-full" style="display: none;"> A fraction of the active supermassive black holes at the centers of galaxies in our Universe are capable of launching extreme kiloparsec-long relativistic jets. These jets are known multiband (radio to $纬$-ray) and multimessenger (neutrino) emitters, and some of them have been monitored over several decades at all accessible wavelengths. However, many open questions remain unanswered about the processes powering these highly energetic phenomena. These jets intrinsically produce soft-to-hard X-ray emission that extends from $E\sim0.1\,\rm keV$ up to $E>100\,\rm keV$. Simultaneous broadband X-ray coverage, combined with excellent timing and imaging capabilities, is required to uncover the physics of jets. Indeed, truly simultaneous soft-to-hard X-ray coverage, in synergy with current and upcoming high-energy facilities (such as IXPE, COSI, CTAO, etc.) and neutrino detectors (e.g., IceCube), would enable us to disentangle the particle population responsible for the high-energy radiation from these jets. A sensitive hard X-ray survey ($F_{8-24\,\rm keV}<10^{-15}\,\rm erg~cm^{-2}~s^{-1}$) could unveil the bulk of their population in the early Universe. Acceleration and radiative processes responsible for the majority of their X-ray emission would be pinned down by microsecond timing capabilities at both soft and hard X-rays. Furthermore, imaging jet structures for the first time in the hard X-ray regime could unravel the origin of their high-energy emission. The proposed Probe-class mission concept High Energy X-ray Probe (HEX-P) combines all these required capabilities, making it the crucial next-generation X-ray telescope in the multi-messenger, time-domain era. HEX-P will be the ideal mission to unravel the science behind the most powerful accelerators in the universe. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.04801v1-abstract-full').style.display = 'none'; document.getElementById('2311.04801v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">30 pages, 12 figures, under review from Frontiers in Astronomy and Space Sciences</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.17819">arXiv:2306.17819</a> <span> [<a href="https://arxiv.org/pdf/2306.17819">pdf</a>, <a href="https://arxiv.org/format/2306.17819">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Multiwavelength Observations of the Blazar PKS 0735+178 in Spatial and Temporal Coincidence with an Astrophysical Neutrino Candidate IceCube-211208A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Acharyya%2C+A">A. Acharyya</a>, <a href="/search/astro-ph?searchtype=author&query=Adams%2C+C+B">C. B. Adams</a>, <a href="/search/astro-ph?searchtype=author&query=Archer%2C+A">A. Archer</a>, <a href="/search/astro-ph?searchtype=author&query=Bangale%2C+P">P. Bangale</a>, <a href="/search/astro-ph?searchtype=author&query=Bartkoske%2C+J+T">J. T. Bartkoske</a>, <a href="/search/astro-ph?searchtype=author&query=Batista%2C+P">P. Batista</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Brill%2C+A">A. Brill</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Christiansen%2C+J+L">J. L. Christiansen</a>, <a href="/search/astro-ph?searchtype=author&query=Chromey%2C+A+J">A. J. Chromey</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">A. Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Foote%2C+G+M">G. M. Foote</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">A. Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Gallagher%2C+G">G. Gallagher</a>, <a href="/search/astro-ph?searchtype=author&query=Hanlon%2C+W">W. Hanlon</a>, <a href="/search/astro-ph?searchtype=author&query=Hanna%2C+D">D. Hanna</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">O. Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=Hinrichs%2C+C+E">C. E. Hinrichs</a>, <a href="/search/astro-ph?searchtype=author&query=Hoang%2C+J">J. Hoang</a>, <a href="/search/astro-ph?searchtype=author&query=Holder%2C+J">J. Holder</a>, <a href="/search/astro-ph?searchtype=author&query=Humensky%2C+T+B">T. B. Humensky</a> , et al. (185 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2306.17819v1-abstract-short" style="display: inline;"> We report on multiwavelength target-of-opportunity observations of the blazar PKS 0735+178, located 2.2$^\circ$ away from the best-fit position of the IceCube neutrino event IceCube-211208A detected on December 8, 2021. The source was in a high-flux state in the optical, ultraviolet, X-ray, and GeV gamma-ray bands around the time of the neutrino event, exhibiting daily variability in the soft X-ra… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.17819v1-abstract-full').style.display = 'inline'; document.getElementById('2306.17819v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.17819v1-abstract-full" style="display: none;"> We report on multiwavelength target-of-opportunity observations of the blazar PKS 0735+178, located 2.2$^\circ$ away from the best-fit position of the IceCube neutrino event IceCube-211208A detected on December 8, 2021. The source was in a high-flux state in the optical, ultraviolet, X-ray, and GeV gamma-ray bands around the time of the neutrino event, exhibiting daily variability in the soft X-ray flux. The X-ray data from Swift-XRT and NuSTAR characterize the transition between the low-energy and high-energy components of the broadband spectral energy distribution (SED), and the gamma-ray data from Fermi -LAT, VERITAS, and H.E.S.S. require a spectral cut-off near 100 GeV. Both X-ray and gamma-ray measurements provide strong constraints on the leptonic and hadronic models. We analytically explore a synchrotron self-Compton model, an external Compton model, and a lepto-hadronic model. Models that are entirely based on internal photon fields face serious difficulties in matching the observed SED. The existence of an external photon field in the source would instead explain the observed gamma-ray spectral cut-off in both leptonic and lepto-hadronic models and allow a proton jet power that marginally agrees with the Eddington limit in the lepto-hadronic model. We show a numerical lepto-hadronic model with external target photons that reproduces the observed SED and is reasonably consistent with the neutrino event despite requiring a high jet power. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.17819v1-abstract-full').style.display = 'none'; document.getElementById('2306.17819v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages, 3 figures, accepted by ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.17680">arXiv:2306.17680</a> <span> [<a href="https://arxiv.org/pdf/2306.17680">pdf</a>, <a href="https://arxiv.org/format/2306.17680">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-3881/ace347">10.3847/1538-3881/ace347 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A VERITAS/Breakthrough Listen Search for Optical Technosignatures </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Acharyya%2C+A">Atreya Acharyya</a>, <a href="/search/astro-ph?searchtype=author&query=Adams%2C+C">Colin Adams</a>, <a href="/search/astro-ph?searchtype=author&query=Archer%2C+A">Avery Archer</a>, <a href="/search/astro-ph?searchtype=author&query=Bangale%2C+P">Priyadarshini Bangale</a>, <a href="/search/astro-ph?searchtype=author&query=Batista%2C+P">Pedro Batista</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">Wystan Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Brill%2C+A">Aryeh Brill</a>, <a href="/search/astro-ph?searchtype=author&query=Capasso%2C+M">M Capasso</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">Abraham Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Qi Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+J">John Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Foote%2C+G">Gregory Foote</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">Lucy Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">Amy Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Griffin%2C+S">Sean Griffin</a>, <a href="/search/astro-ph?searchtype=author&query=Hanlon%2C+W">William Hanlon</a>, <a href="/search/astro-ph?searchtype=author&query=Hanna%2C+D">David Hanna</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">Olivier Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=Hinrichs%2C+C">Claire Hinrichs</a>, <a href="/search/astro-ph?searchtype=author&query=Hoang%2C+J">John Hoang</a>, <a href="/search/astro-ph?searchtype=author&query=Holder%2C+J">Jamie Holder</a>, <a href="/search/astro-ph?searchtype=author&query=Humensky%2C+T">T. Humensky</a>, <a href="/search/astro-ph?searchtype=author&query=Jin%2C+W">Weidong Jin</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">Philip Kaaret</a> , et al. (43 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2306.17680v1-abstract-short" style="display: inline;"> The Breakthrough Listen Initiative is conducting a program using multiple telescopes around the world to search for "technosignatures": artificial transmitters of extraterrestrial origin from beyond our solar system. The VERITAS Collaboration joined this program in 2018, and provides the capability to search for one particular technosignature: optical pulses of a few nanoseconds duration detectabl… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.17680v1-abstract-full').style.display = 'inline'; document.getElementById('2306.17680v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.17680v1-abstract-full" style="display: none;"> The Breakthrough Listen Initiative is conducting a program using multiple telescopes around the world to search for "technosignatures": artificial transmitters of extraterrestrial origin from beyond our solar system. The VERITAS Collaboration joined this program in 2018, and provides the capability to search for one particular technosignature: optical pulses of a few nanoseconds duration detectable over interstellar distances. We report here on the analysis and results of dedicated VERITAS observations of Breakthrough Listen targets conducted in 2019 and 2020 and of archival VERITAS data collected since 2012. Thirty hours of dedicated observations of 136 targets and 249 archival observations of 140 targets were analyzed and did not reveal any signals consistent with a technosignature. The results are used to place limits on the fraction of stars hosting transmitting civilizations. We also discuss the minimum-pulse sensitivity of our observations and present VERITAS observations of CALIOP: a space-based pulsed laser onboard the CALIPSO satellite. The detection of these pulses with VERITAS, using the analysis techniques developed for our technosignature search, allows a test of our analysis efficiency and serves as an important proof-of-principle. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.17680v1-abstract-full').style.display = 'none'; document.getElementById('2306.17680v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 7 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.13497">arXiv:2305.13497</a> <span> [<a href="https://arxiv.org/pdf/2305.13497">pdf</a>, <a href="https://arxiv.org/format/2305.13497">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Discovery of X-ray polarization angle rotation in active galaxy Mrk 421 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Ehlert%2C+S+R">Steven R. Ehlert</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Donnarumma%2C+I">Immacolata Donnarumma</a>, <a href="/search/astro-ph?searchtype=author&query=Tavecchio%2C+F">Fabrizio Tavecchio</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Kiehlmann%2C+S">Sebastian Kiehlmann</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Puccetti%2C+S">Simonetta Puccetti</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Perri%2C+M">Matteo Perri</a>, <a href="/search/astro-ph?searchtype=author&query=Pacciani%2C+L">Luigi Pacciani</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Romani%2C+R+W">Roger W. Romani</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D">Dmitry Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Bourbah%2C+I+G">Ioakeim G. Bourbah</a>, <a href="/search/astro-ph?searchtype=author&query=Kontopodis%2C+E">Evangelos Kontopodis</a>, <a href="/search/astro-ph?searchtype=author&query=Mandarakas%2C+N">Nikos Mandarakas</a>, <a href="/search/astro-ph?searchtype=author&query=Romanopoulos%2C+S">Stylianos Romanopoulos</a>, <a href="/search/astro-ph?searchtype=author&query=Skalidis%2C+R">Raphael Skalidis</a> , et al. (118 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.13497v1-abstract-short" style="display: inline;"> The magnetic field conditions in astrophysical relativistic jets can be probed by multiwavelength polarimetry, which has been recently extended to X-rays. For example, one can track how the magnetic field changes in the flow of the radiating particles by observing rotations of the electric vector position angle $唯$. Here we report the discovery of a $唯_{\mathrm x}$ rotation in the X-ray band in th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.13497v1-abstract-full').style.display = 'inline'; document.getElementById('2305.13497v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.13497v1-abstract-full" style="display: none;"> The magnetic field conditions in astrophysical relativistic jets can be probed by multiwavelength polarimetry, which has been recently extended to X-rays. For example, one can track how the magnetic field changes in the flow of the radiating particles by observing rotations of the electric vector position angle $唯$. Here we report the discovery of a $唯_{\mathrm x}$ rotation in the X-ray band in the blazar Mrk 421 at an average flux state. Across the 5 days of Imaging X-ray Polarimetry Explorer (IXPE) observations of 4-6 and 7-9 June 2022, $唯_{\mathrm x}$ rotated in total by $\geq360^\circ$. Over the two respective date ranges, we find constant, within uncertainties, rotation rates ($80 \pm 9$ and $91 \pm 8 ^\circ/\rm day$) and polarization degrees ($螤_{\mathrm x}=10\%\pm1\%$). Simulations of a random walk of the polarization vector indicate that it is unlikely that such rotation(s) are produced by a stochastic process. The X-ray emitting site does not completely overlap the radio/infrared/optical emission sites, as no similar rotation of $唯$ was observed in quasi-simultaneous data at longer wavelengths. We propose that the observed rotation was caused by a helical magnetic structure in the jet, illuminated in the X-rays by a localized shock propagating along this helix. The optically emitting region likely lies in a sheath surrounding an inner spine where the X-ray radiation is released. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.13497v1-abstract-full').style.display = 'none'; document.getElementById('2305.13497v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.02860">arXiv:2305.02860</a> <span> [<a href="https://arxiv.org/pdf/2305.02860">pdf</a>, <a href="https://arxiv.org/format/2305.02860">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/acd2d0">10.3847/1538-4357/acd2d0 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> VERITAS discovery of very high energy gamma-ray emission from S3 1227+25 and multiwavelength observations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Acharyya%2C+A">Atreya Acharyya</a>, <a href="/search/astro-ph?searchtype=author&query=Adams%2C+C">Colin Adams</a>, <a href="/search/astro-ph?searchtype=author&query=Archer%2C+A">Avery Archer</a>, <a href="/search/astro-ph?searchtype=author&query=Bangale%2C+P">Priyadarshini Bangale</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">Wystan Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Brill%2C+A">Aryeh Brill</a>, <a href="/search/astro-ph?searchtype=author&query=Christiansen%2C+J">Jodi Christiansen</a>, <a href="/search/astro-ph?searchtype=author&query=Chromey%2C+A">Alisha Chromey</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">Abe Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Qi Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+J">John Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Foote%2C+G">Gregory Foote</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">Lucy Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">Amy Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Gallagher%2C+G">Greg Gallagher</a>, <a href="/search/astro-ph?searchtype=author&query=Hanlon%2C+W">William Hanlon</a>, <a href="/search/astro-ph?searchtype=author&query=Hanna%2C+D">David Hanna</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">Olivier Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=Hinrichs%2C+C">Claire Hinrichs</a>, <a href="/search/astro-ph?searchtype=author&query=Hoang%2C+J">John Hoang</a>, <a href="/search/astro-ph?searchtype=author&query=Holder%2C+J">Jamie Holder</a>, <a href="/search/astro-ph?searchtype=author&query=Jin%2C+W">Weidong Jin</a>, <a href="/search/astro-ph?searchtype=author&query=Johnson%2C+M">Madalyn Johnson</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">Philip Kaaret</a> , et al. (46 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.02860v1-abstract-short" style="display: inline;"> We report the detection of very high energy gamma-ray emission from the blazar S3 1227+25 (VER J1230+253) with the Very Energetic Radiation Imaging Telescope Array System (VERITAS). VERITAS observations of the source were triggered by the detection of a hard-spectrum GeV flare on May 15, 2015 with the Fermi-Large Area Telescope (LAT). A combined five-hour VERITAS exposure on May 16th and May 18th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.02860v1-abstract-full').style.display = 'inline'; document.getElementById('2305.02860v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.02860v1-abstract-full" style="display: none;"> We report the detection of very high energy gamma-ray emission from the blazar S3 1227+25 (VER J1230+253) with the Very Energetic Radiation Imaging Telescope Array System (VERITAS). VERITAS observations of the source were triggered by the detection of a hard-spectrum GeV flare on May 15, 2015 with the Fermi-Large Area Telescope (LAT). A combined five-hour VERITAS exposure on May 16th and May 18th resulted in a strong 13$蟽$ detection with a differential photon spectral index, $螕$ = 3.8 $\pm$ 0.4, and a flux level at 9% of the Crab Nebula above 120 GeV. This also triggered target of opportunity observations with Swift, optical photometry, polarimetry and radio measurements, also presented in this work, in addition to the VERITAS and Fermi-LAT data. A temporal analysis of the gamma-ray flux during this period finds evidence of a shortest variability timescale of $蟿_{obs}$ = 6.2 $\pm$ 0.9 hours, indicating emission from compact regions within the jet, and the combined gamma-ray spectrum shows no strong evidence of a spectral cut-off. An investigation into correlations between the multiwavelength observations found evidence of optical and gamma-ray correlations, suggesting a single-zone model of emission. Finally, the multiwavelength spectral energy distribution is well described by a simple one-zone leptonic synchrotron self-Compton radiation model. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.02860v1-abstract-full').style.display = 'none'; document.getElementById('2305.02860v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">18 pages, 6 figures. Accepted for publication in the Astrophysical Journal (ApJ)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.06686">arXiv:2302.06686</a> <span> [<a href="https://arxiv.org/pdf/2302.06686">pdf</a>, <a href="https://arxiv.org/format/2302.06686">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/acb7e6">10.3847/1538-4357/acb7e6 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> VERITAS and Fermi-LAT constraints on the Gamma-ray Emission from Superluminous Supernovae SN2015bn and SN2017egm </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Acharyya%2C+A">A. Acharyya</a>, <a href="/search/astro-ph?searchtype=author&query=Adams%2C+C+B">C. B. Adams</a>, <a href="/search/astro-ph?searchtype=author&query=Bangale%2C+P">P. Bangale</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Capasso%2C+M">M. Capasso</a>, <a href="/search/astro-ph?searchtype=author&query=Dwarkadas%2C+V+V">V. V. Dwarkadas</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">A. Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+J+P">J. P. Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Foote%2C+G+M">G. M. Foote</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">A. Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Gallagher%2C+G">G. Gallagher</a>, <a href="/search/astro-ph?searchtype=author&query=Gent%2C+A">A. Gent</a>, <a href="/search/astro-ph?searchtype=author&query=Hanlon%2C+W+F">W. F Hanlon</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">O. Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=Holder%2C+J">J. Holder</a>, <a href="/search/astro-ph?searchtype=author&query=Humensky%2C+T+B">T. B. Humensky</a>, <a href="/search/astro-ph?searchtype=author&query=Jin%2C+W">W. Jin</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">P. Kaaret</a>, <a href="/search/astro-ph?searchtype=author&query=Kertzman%2C+M">M. Kertzman</a>, <a href="/search/astro-ph?searchtype=author&query=Kherlakian%2C+M">M. Kherlakian</a>, <a href="/search/astro-ph?searchtype=author&query=Kieda%2C+D">D. Kieda</a> , et al. (34 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2302.06686v1-abstract-short" style="display: inline;"> Superluminous supernovae (SLSNe) are a rare class of stellar explosions with luminosities ~10-100 times greater than ordinary core-collapse supernovae. One popular model to explain the enhanced optical output of hydrogen-poor (Type I) SLSNe invokes energy injection from a rapidly spinning magnetar. A prediction in this case is that high-energy gamma rays, generated in the wind nebula of the magnet… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.06686v1-abstract-full').style.display = 'inline'; document.getElementById('2302.06686v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.06686v1-abstract-full" style="display: none;"> Superluminous supernovae (SLSNe) are a rare class of stellar explosions with luminosities ~10-100 times greater than ordinary core-collapse supernovae. One popular model to explain the enhanced optical output of hydrogen-poor (Type I) SLSNe invokes energy injection from a rapidly spinning magnetar. A prediction in this case is that high-energy gamma rays, generated in the wind nebula of the magnetar, could escape through the expanding supernova ejecta at late times (months or more after optical peak). This paper presents a search for gamma-ray emission in the broad energy band from 100 MeV to 30 TeV from two Type I SLSNe, SN2015bn, and SN2017egm, using observations from Fermi-LAT and VERITAS. Although no gamma-ray emission was detected from either source, the derived upper limits approach the putative magnetar's spin-down luminosity. Prospects are explored for detecting very-high-energy (VHE; 100 GeV - 100 TeV) emission from SLSNe-I with existing and planned facilities such as VERITAS and CTA. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.06686v1-abstract-full').style.display = 'none'; document.getElementById('2302.06686v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">20 pages, 7 figures, 2 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2301.04498">arXiv:2301.04498</a> <span> [<a href="https://arxiv.org/pdf/2301.04498">pdf</a>, <a href="https://arxiv.org/ps/2301.04498">ps</a>, <a href="https://arxiv.org/format/2301.04498">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/2515-5172/acb147">10.3847/2515-5172/acb147 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> VTSCat: The VERITAS Catalog of Gamma-Ray Observations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Acharyya%2C+A">A. Acharyya</a>, <a href="/search/astro-ph?searchtype=author&query=Adams%2C+C+B">C. B. Adams</a>, <a href="/search/astro-ph?searchtype=author&query=Archer%2C+A">A. Archer</a>, <a href="/search/astro-ph?searchtype=author&query=Bangale%2C+P">P. Bangale</a>, <a href="/search/astro-ph?searchtype=author&query=Bartkoske%2C+J+T">J. T. Bartkoske</a>, <a href="/search/astro-ph?searchtype=author&query=Batista%2C+P">P. Batista</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Brill%2C+A">A. Brill</a>, <a href="/search/astro-ph?searchtype=author&query=Capasso%2C+M">M. Capasso</a>, <a href="/search/astro-ph?searchtype=author&query=Christiansen%2C+J+L">J. L. Christiansen</a>, <a href="/search/astro-ph?searchtype=author&query=Chromey%2C+A+J">A. J. Chromey</a>, <a href="/search/astro-ph?searchtype=author&query=Daniel%2C+M+K">M. K. Daniel</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">A. Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Farrell%2C+K+A">K. A Farrell</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+J+P">J. P. Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Foote%2C+G+M">G. M Foote</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">A. Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Gallagher%2C+G">G. Gallagher</a>, <a href="/search/astro-ph?searchtype=author&query=Gent%2C+A">A. Gent</a>, <a href="/search/astro-ph?searchtype=author&query=Giuri%2C+C">C. Giuri</a>, <a href="/search/astro-ph?searchtype=author&query=Gueta%2C+O">O. Gueta</a> , et al. (64 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2301.04498v2-abstract-short" style="display: inline;"> The ground-based gamma-ray observatory VERITAS (Very Energetic Radiation Imaging Telescope Array System) is sensitive to photons of astrophysical origin with energies in the range between $\approx 85$ GeV to $\approx 30$ TeV. The instrument consists of four 12-m diameter imaging Cherenkov telescopes operating at the Fred Lawrence Whipple Observatory (FLWO) in southern Arizona. VERITAS started four… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2301.04498v2-abstract-full').style.display = 'inline'; document.getElementById('2301.04498v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2301.04498v2-abstract-full" style="display: none;"> The ground-based gamma-ray observatory VERITAS (Very Energetic Radiation Imaging Telescope Array System) is sensitive to photons of astrophysical origin with energies in the range between $\approx 85$ GeV to $\approx 30$ TeV. The instrument consists of four 12-m diameter imaging Cherenkov telescopes operating at the Fred Lawrence Whipple Observatory (FLWO) in southern Arizona. VERITAS started four-telescope operations in 2007 and collects about 1100 hours of good-weather data per year. The VERITAS collaboration has published over 100 journal articles since 2008 reporting on gamma-ray observations of a large variety of objects: Galactic sources like supernova remnants, pulsar wind nebulae, and binary systems; extragalactic sources like star forming galaxies, dwarf-spheroidal galaxies, and highly-variable active galactic nuclei. This note presents VTSCat: the catalog of high-level data products from all VERITAS publications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2301.04498v2-abstract-full').style.display = 'none'; document.getElementById('2301.04498v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 January, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 January, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Version with corrected author list</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Research Notes of the AAS, Volume 7, Number 1, 2023 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2209.09785">arXiv:2209.09785</a> <span> [<a href="https://arxiv.org/pdf/2209.09785">pdf</a>, <a href="https://arxiv.org/format/2209.09785">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stac2686">10.1093/mnras/stac2686 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Gamma-ray observations of MAXI J1820+070 during the 2018 outburst </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Abe%2C+H">H. Abe</a>, <a href="/search/astro-ph?searchtype=author&query=Abe%2C+S">S. Abe</a>, <a href="/search/astro-ph?searchtype=author&query=Acciari%2C+V+A">V. A. Acciari</a>, <a href="/search/astro-ph?searchtype=author&query=Aniello%2C+T">T. Aniello</a>, <a href="/search/astro-ph?searchtype=author&query=Ansoldi%2C+S">S. Ansoldi</a>, <a href="/search/astro-ph?searchtype=author&query=Antonelli%2C+L+A">L. A. Antonelli</a>, <a href="/search/astro-ph?searchtype=author&query=Engels%2C+A+A">A. Arbet Engels</a>, <a href="/search/astro-ph?searchtype=author&query=Arcaro%2C+C">C. Arcaro</a>, <a href="/search/astro-ph?searchtype=author&query=Artero%2C+M">M. Artero</a>, <a href="/search/astro-ph?searchtype=author&query=Asano%2C+K">K. Asano</a>, <a href="/search/astro-ph?searchtype=author&query=Baack%2C+D">D. Baack</a>, <a href="/search/astro-ph?searchtype=author&query=Babi%C4%87%2C+A">A. Babi膰</a>, <a href="/search/astro-ph?searchtype=author&query=Baquero%2C+A">A. Baquero</a>, <a href="/search/astro-ph?searchtype=author&query=de+Almeida%2C+U+B">U. Barres de Almeida</a>, <a href="/search/astro-ph?searchtype=author&query=Barrio%2C+J+A">J. A. Barrio</a>, <a href="/search/astro-ph?searchtype=author&query=Batkovi%C4%87%2C+I">I. Batkovi膰</a>, <a href="/search/astro-ph?searchtype=author&query=Baxter%2C+J">J. Baxter</a>, <a href="/search/astro-ph?searchtype=author&query=Gonz%C3%A1lez%2C+J+B">J. Becerra Gonz谩lez</a>, <a href="/search/astro-ph?searchtype=author&query=Bednarek%2C+W">W. Bednarek</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardini%2C+E">E. Bernardini</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardos%2C+M">M. Bernardos</a>, <a href="/search/astro-ph?searchtype=author&query=Berti%2C+A">A. Berti</a>, <a href="/search/astro-ph?searchtype=author&query=Besenrieder%2C+J">J. Besenrieder</a>, <a href="/search/astro-ph?searchtype=author&query=Bhattacharyya%2C+W">W. Bhattacharyya</a>, <a href="/search/astro-ph?searchtype=author&query=Bigongiari%2C+C">C. Bigongiari</a> , et al. (418 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2209.09785v2-abstract-short" style="display: inline;"> MAXI J1820+070 is a low-mass X-ray binary with a black hole as a compact object. This binary underwent an exceptionally bright X-ray outburst from March to October 2018, showing evidence of a non-thermal particle population through its radio emission during this whole period. The combined results of 59.5 hours of observations of the MAXI J1820+070 outburst with the H.E.S.S., MAGIC and VERITAS expe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.09785v2-abstract-full').style.display = 'inline'; document.getElementById('2209.09785v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2209.09785v2-abstract-full" style="display: none;"> MAXI J1820+070 is a low-mass X-ray binary with a black hole as a compact object. This binary underwent an exceptionally bright X-ray outburst from March to October 2018, showing evidence of a non-thermal particle population through its radio emission during this whole period. The combined results of 59.5 hours of observations of the MAXI J1820+070 outburst with the H.E.S.S., MAGIC and VERITAS experiments at energies above 200 GeV are presented, together with Fermi-LAT data between 0.1 and 500 GeV, and multiwavelength observations from radio to X-rays. Gamma-ray emission is not detected from MAXI J1820+070, but the obtained upper limits and the multiwavelength data allow us to put meaningful constraints on the source properties under reasonable assumptions regarding the non-thermal particle population and the jet synchrotron spectrum. In particular, it is possible to show that, if a high-energy gamma-ray emitting region is present during the hard state of the source, its predicted flux should be at most a factor of 20 below the obtained Fermi-LAT upper limits, and closer to them for magnetic fields significantly below equipartition. During the state transitions, under the plausible assumption that electrons are accelerated up to ~ 500 GeV, the multiwavelength data and the gamma-ray upper limits lead consistently to the conclusion that a potential high-energy and very-high-energy gamma-ray emitting region should be located at a distance from the black hole ranging between 10^11 and 10^13 cm. Similar outbursts from low-mass X-ray binaries might be detectable in the near future with upcoming instruments such as CTA. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.09785v2-abstract-full').style.display = 'none'; document.getElementById('2209.09785v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 September, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 5 figures. Accepted for publication in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2209.07184">arXiv:2209.07184</a> <span> [<a href="https://arxiv.org/pdf/2209.07184">pdf</a>, <a href="https://arxiv.org/format/2209.07184">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/2041-8213/ac913a">10.3847/2041-8213/ac913a <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The X-ray Polarization View of Mrk~421 in an Average Flux State as Observed by the Imaging X-ray Polarimetry Explorer </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Donnarumma%2C+I">Immacolata Donnarumma</a>, <a href="/search/astro-ph?searchtype=author&query=Tavecchio%2C+F">Fabrizio Tavecchio</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Ivan Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Barnounin%2C+T">Thibault Barnounin</a>, <a href="/search/astro-ph?searchtype=author&query=Cibrario%2C+N">Nicol貌 Cibrario</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Lalla%2C+N">Niccol貌 Di Lalla</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Escudero%2C+J">Juan Escudero</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D">Dawoon Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Kouch%2C+P+M">Pouya M. Kouch</a>, <a href="/search/astro-ph?searchtype=author&query=Lindfors%2C+E">Elina Lindfors</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Madejski%2C+G">Grzegorz Madejski</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Myserlis%2C+I">Ioannis Myserlis</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Omodei%2C+N">Nicola Omodei</a>, <a href="/search/astro-ph?searchtype=author&query=Pacciani%2C+L">Luigi Pacciani</a>, <a href="/search/astro-ph?searchtype=author&query=Paggi%2C+A">Alessandro Paggi</a> , et al. (78 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2209.07184v1-abstract-short" style="display: inline;"> Particle acceleration mechanisms in supermassive black hole jets, such as shock acceleration, magnetic reconnection, and turbulence, are expected to have observable signatures in the multi-wavelength polarization properties of blazars. The recent launch of the Imaging X-ray Polarimetry Explorer (IXPE) enables us, for the first time, to use polarization in the X-ray band (2-8 keV) to probe the prop… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.07184v1-abstract-full').style.display = 'inline'; document.getElementById('2209.07184v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2209.07184v1-abstract-full" style="display: none;"> Particle acceleration mechanisms in supermassive black hole jets, such as shock acceleration, magnetic reconnection, and turbulence, are expected to have observable signatures in the multi-wavelength polarization properties of blazars. The recent launch of the Imaging X-ray Polarimetry Explorer (IXPE) enables us, for the first time, to use polarization in the X-ray band (2-8 keV) to probe the properties of the jet synchrotron emission in high-frequency-peaked BL Lac objects (HSPs). We report the discovery of X-ray linear polarization (degree $螤_{\rm x}=15\pm$2\% and electric-vector position angle $唯_{\rm x}=35^\circ\pm4^\circ$) from the jet of the HSP Mrk~421 in an average X-ray flux state. At the same time, the degree of polarization at optical, infrared, and millimeter wavelengths was found to be lower by at least a factor of 3. During the IXPE pointing, the X-ray flux of the source increased by a factor of 2.2, while the polarization behavior was consistent with no variability. The higher level of $螤_{\rm x}$ compared to longer wavelengths, and the absence of significant polarization variability, suggest a shock as the most likely X-ray emission site in the jet of Mrk 421 during the observation. The multiwavelength polarization properties are consistent with an energy-stratified electron population, where the particles emitting at longer wavelengths are located farther from the acceleration site, where they experience a more disordered magnetic field. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.07184v1-abstract-full').style.display = 'none'; document.getElementById('2209.07184v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 September, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">accepted for ApJ Letters</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2209.06227">arXiv:2209.06227</a> <span> [<a href="https://arxiv.org/pdf/2209.06227">pdf</a>, <a href="https://arxiv.org/format/2209.06227">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41586-022-05338-0">10.1038/s41586-022-05338-0 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Polarized Blazar X-rays imply particle acceleration in shocks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Berdyugin%2C+A+V">Andrei V. Berdyugin</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardos%2C+M+I">Maria I. Bernardos</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">Giacomo Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Borman%2C+G+A">George A. Borman</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">Carolina Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Casanova%2C+V">V铆ctor Casanova</a>, <a href="/search/astro-ph?searchtype=author&query=Cavazzuti%2C+E">Elisabetta Cavazzuti</a>, <a href="/search/astro-ph?searchtype=author&query=Cavero%2C+N+R">Nicole Rodriguez Cavero</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Lalla%2C+N">Niccol贸 Di Lalla</a>, <a href="/search/astro-ph?searchtype=author&query=Donnarumma%2C+I">Immacolata Donnarumma</a>, <a href="/search/astro-ph?searchtype=author&query=Ehlert%2C+S+R">Steven R. Ehlert</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Escudero%2C+J">Juan Escudero</a>, <a href="/search/astro-ph?searchtype=author&query=Garc%C3%ADa-Comas%2C+M">Maya Garc铆a-Comas</a>, <a href="/search/astro-ph?searchtype=author&query=Ag%C3%ADs-Gonz%C3%A1lez%2C+B">Beatriz Ag铆s-Gonz谩lez</a>, <a href="/search/astro-ph?searchtype=author&query=Husillos%2C+C">C茅sar Husillos</a>, <a href="/search/astro-ph?searchtype=author&query=Jormanainen%2C+J">Jenni Jormanainen</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Kagitani%2C+M">Masato Kagitani</a>, <a href="/search/astro-ph?searchtype=author&query=Kopatskaya%2C+E+N">Evgenia N. Kopatskaya</a>, <a href="/search/astro-ph?searchtype=author&query=Kravtsov%2C+V">Vadim Kravtsov</a> , et al. (103 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2209.06227v2-abstract-short" style="display: inline;"> Most of the light from blazars, active galactic nuclei with jets of magnetized plasma that point nearly along the line of sight, is produced by high-energy particles, up to $\sim 1$ TeV. Although the jets are known to be ultimately powered by a supermassive black hole, how the particles are accelerated to such high energies has been an unanswered question. The process must be related to the magnet… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.06227v2-abstract-full').style.display = 'inline'; document.getElementById('2209.06227v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2209.06227v2-abstract-full" style="display: none;"> Most of the light from blazars, active galactic nuclei with jets of magnetized plasma that point nearly along the line of sight, is produced by high-energy particles, up to $\sim 1$ TeV. Although the jets are known to be ultimately powered by a supermassive black hole, how the particles are accelerated to such high energies has been an unanswered question. The process must be related to the magnetic field, which can be probed by observations of the polarization of light from the jets. Measurements of the radio to optical polarization - the only range available until now - probe extended regions of the jet containing particles that left the acceleration site days to years earlier (Jorstad et al., 2005; Marin et al., 2018; Blinov et al., 2021), and hence do not directly explore the acceleration mechanism, as could X-ray measurements. Here we report the detection of X-ray polarization from the blazar Markarian~501 (Mrk~501). We measure an X-ray linear polarization degree $螤_X \sim10\%$, a factor of $\sim2$ higher than the value at optical wavelengths, with a polarization angle parallel to the radio jet. This points to a shock front as the source of particle acceleration, and also implies that the plasma becomes increasingly turbulent with distance from the shock. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.06227v2-abstract-full').style.display = 'none'; document.getElementById('2209.06227v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 September, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">34 pages, 4 figures, 4 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> 2022, Nature, 611, 677-681 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2205.08898">arXiv:2205.08898</a> <span> [<a href="https://arxiv.org/pdf/2205.08898">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1126/science.add0080">10.1126/science.add0080 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Polarized x-rays from a magnetar </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Taverna%2C+R">Roberto Taverna</a>, <a href="/search/astro-ph?searchtype=author&query=Turolla%2C+R">Roberto Turolla</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Heyl%2C+J">Jeremy Heyl</a>, <a href="/search/astro-ph?searchtype=author&query=Zane%2C+S">Silvia Zane</a>, <a href="/search/astro-ph?searchtype=author&query=Baldini%2C+L">Luca Baldini</a>, <a href="/search/astro-ph?searchtype=author&query=Caniulef%2C+D+G">Denis Gonz谩lez Caniulef</a>, <a href="/search/astro-ph?searchtype=author&query=Bachetti%2C+M">Matteo Bachetti</a>, <a href="/search/astro-ph?searchtype=author&query=Rankin%2C+J">John Rankin</a>, <a href="/search/astro-ph?searchtype=author&query=Caiazzo%2C+I">Ilaria Caiazzo</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Lalla%2C+N">Niccol貌 Di Lalla</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">Victor Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Gau%2C+E">Ephraim Gau</a>, <a href="/search/astro-ph?searchtype=author&query=K%C4%B1rm%C4%B1z%C4%B1bayrak%2C+D">Demet K谋rm谋z谋bayrak</a>, <a href="/search/astro-ph?searchtype=author&query=Krawczynski%2C+H">Henric Krawczynski</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Ng%2C+M">Mason Ng</a>, <a href="/search/astro-ph?searchtype=author&query=Omodei%2C+N">Nicola Omodei</a>, <a href="/search/astro-ph?searchtype=author&query=Tamagawa%2C+T">Toru Tamagawa</a>, <a href="/search/astro-ph?searchtype=author&query=Uchiyama%2C+K">Keisuke Uchiyama</a>, <a href="/search/astro-ph?searchtype=author&query=Weisskopf%2C+M+C">Martin C. Weisskopf</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Ivan Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Antonelli%2C+L+A">Lucio A. Antonelli</a>, <a href="/search/astro-ph?searchtype=author&query=Baumgartner%2C+W+H">Wayne H. Baumgartner</a> , et al. (71 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2205.08898v1-abstract-short" style="display: inline;"> We report on the first detection of linearly polarized x-ray emission from an ultra-magnetized neutron star with the Imaging X-ray Polarimetry Explorer (IXPE). The IXPE 35 observations of the anomalous x-ray pulsar 4U 0142+61 reveal a linear polarization degree of $(12\pm 1)\%$ throughout the IXPE 2--8 keV band. We detect a substantial variation of the polarization with energy: the degree is… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2205.08898v1-abstract-full').style.display = 'inline'; document.getElementById('2205.08898v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2205.08898v1-abstract-full" style="display: none;"> We report on the first detection of linearly polarized x-ray emission from an ultra-magnetized neutron star with the Imaging X-ray Polarimetry Explorer (IXPE). The IXPE 35 observations of the anomalous x-ray pulsar 4U 0142+61 reveal a linear polarization degree of $(12\pm 1)\%$ throughout the IXPE 2--8 keV band. We detect a substantial variation of the polarization with energy: the degree is $(14\pm 1)\%$ at 2--4 keV and $(41\pm 7)\%$ at 5.5--8 keV, while it drops below the instrumental sensitivity around 4--5 keV, where the polarization angle swings by $\sim 90^\circ$. The IXPE observations give us completely new information about the properties of the neutron star surface and magnetosphere and lend further support to the presence of the quantum mechanical effect of vacuum birefringence. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2205.08898v1-abstract-full').style.display = 'none'; document.getElementById('2205.08898v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 May, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">32 pages, 9 figures, 3 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.09761">arXiv:2204.09761</a> <span> [<a href="https://arxiv.org/pdf/2204.09761">pdf</a>, <a href="https://arxiv.org/format/2204.09761">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.astropartphys.2022.102749">10.1016/j.astropartphys.2022.102749 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Performance of the X-Calibur Hard X-Ray Polarimetry Mission during its 2018/19 Long-Duration Balloon Flight </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Abarr%2C+Q">Quincy Abarr</a>, <a href="/search/astro-ph?searchtype=author&query=Beheshtipour%2C+B">Banafsheh Beheshtipour</a>, <a href="/search/astro-ph?searchtype=author&query=Beilicke%2C+M">Matthias Beilicke</a>, <a href="/search/astro-ph?searchtype=author&query=Bose%2C+R">Richard Bose</a>, <a href="/search/astro-ph?searchtype=author&query=Braun%2C+D">Dana Braun</a>, <a href="/search/astro-ph?searchtype=author&query=de+Geronimo%2C+G">Gianluigi de Geronimo</a>, <a href="/search/astro-ph?searchtype=author&query=Dowkontt%2C+P">Paul Dowkontt</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Gadson%2C+T">Thomas Gadson</a>, <a href="/search/astro-ph?searchtype=author&query=Guarino%2C+V">Victor Guarino</a>, <a href="/search/astro-ph?searchtype=author&query=Heatwole%2C+S">Scott Heatwole</a>, <a href="/search/astro-ph?searchtype=author&query=Hossen%2C+M+A">Md. Arman Hossen</a>, <a href="/search/astro-ph?searchtype=author&query=Iyer%2C+N+K">Nirmal K. Iyer</a>, <a href="/search/astro-ph?searchtype=author&query=Kislat%2C+F">Fabian Kislat</a>, <a href="/search/astro-ph?searchtype=author&query=Kiss%2C+M">M贸zsi Kiss</a>, <a href="/search/astro-ph?searchtype=author&query=Kitaguchi%2C+T">Takao Kitaguchi</a>, <a href="/search/astro-ph?searchtype=author&query=Krawczynski%2C+H">Henric Krawczynski</a>, <a href="/search/astro-ph?searchtype=author&query=Lanzi%2C+R+J">R. James Lanzi</a>, <a href="/search/astro-ph?searchtype=author&query=Li%2C+S">Shaorui Li</a>, <a href="/search/astro-ph?searchtype=author&query=Lisalda%2C+L">Lindsey Lisalda</a>, <a href="/search/astro-ph?searchtype=author&query=Okajima%2C+T">Takashi Okajima</a>, <a href="/search/astro-ph?searchtype=author&query=Pearce%2C+M">Mark Pearce</a>, <a href="/search/astro-ph?searchtype=author&query=Peterson%2C+Z">Zachary Peterson</a>, <a href="/search/astro-ph?searchtype=author&query=Press%2C+L">Logan Press</a>, <a href="/search/astro-ph?searchtype=author&query=Rauch%2C+B">Brian Rauch</a> , et al. (6 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2204.09761v1-abstract-short" style="display: inline;"> X-Calibur is a balloon-borne telescope that measures the polarization of high-energy X-rays in the 15--50keV energy range. The instrument makes use of the fact that X-rays scatter preferentially perpendicular to the polarization direction. A beryllium scattering element surrounded by pixellated CZT detectors is located at the focal point of the InFOC渭S hard X-ray mirror. The instrument was launche… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.09761v1-abstract-full').style.display = 'inline'; document.getElementById('2204.09761v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.09761v1-abstract-full" style="display: none;"> X-Calibur is a balloon-borne telescope that measures the polarization of high-energy X-rays in the 15--50keV energy range. The instrument makes use of the fact that X-rays scatter preferentially perpendicular to the polarization direction. A beryllium scattering element surrounded by pixellated CZT detectors is located at the focal point of the InFOC渭S hard X-ray mirror. The instrument was launched for a long-duration balloon (LDB) flight from McMurdo (Antarctica) on December 29, 2018, and obtained the first constraints of the hard X-ray polarization of an accretion-powered pulsar. Here, we describe the characterization and calibration of the instrument on the ground and its performance during the flight, as well as simulations of particle backgrounds and a comparison to measured rates. The pointing system and polarimeter achieved the excellent projected performance. The energy detection threshold for the anticoincidence system was found to be higher than expected and it exhibited unanticipated dead time. Both issues will be remedied for future flights. Overall, the mission performance was nominal, and results will inform the design of the follow-up mission XL-Calibur, which is scheduled to be launched in summer 2022. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.09761v1-abstract-full').style.display = 'none'; document.getElementById('2204.09761v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 April, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 31 figures, submitted to Astropart. Phys</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2203.08169">arXiv:2203.08169</a> <span> [<a href="https://arxiv.org/pdf/2203.08169">pdf</a>, <a href="https://arxiv.org/format/2203.08169">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1117/1.JATIS.8.1.014007">10.1117/1.JATIS.8.1.014007 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Design and Performance of the Prototype Schwarzschild-Couder Telescope Camera </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Adams%2C+C+B">Colin B. Adams</a>, <a href="/search/astro-ph?searchtype=author&query=Ambrosi%2C+G">Giovanni Ambrosi</a>, <a href="/search/astro-ph?searchtype=author&query=Ambrosio%2C+M">Michelangelo Ambrosio</a>, <a href="/search/astro-ph?searchtype=author&query=Aramo%2C+C">Carla Aramo</a>, <a href="/search/astro-ph?searchtype=author&query=Arlen%2C+T">Timothy Arlen</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">Wystan Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Bertucci%2C+B">Bruna Bertucci</a>, <a href="/search/astro-ph?searchtype=author&query=Bissaldi%2C+E">Elisabetta Bissaldi</a>, <a href="/search/astro-ph?searchtype=author&query=Biteau%2C+J">Jonathan Biteau</a>, <a href="/search/astro-ph?searchtype=author&query=Bitossi%2C+M">Massimiliano Bitossi</a>, <a href="/search/astro-ph?searchtype=author&query=Boiano%2C+A">Alfonso Boiano</a>, <a href="/search/astro-ph?searchtype=author&query=Bonavolont%C3%A0%2C+C">Carmela Bonavolont脿</a>, <a href="/search/astro-ph?searchtype=author&query=Bose%2C+R">Richard Bose</a>, <a href="/search/astro-ph?searchtype=author&query=Bouvier%2C+A">Aurelien Bouvier</a>, <a href="/search/astro-ph?searchtype=author&query=Buscemi%2C+M">Mario Buscemi</a>, <a href="/search/astro-ph?searchtype=author&query=Brill%2C+A">Aryeh Brill</a>, <a href="/search/astro-ph?searchtype=author&query=Brown%2C+A+M">Anthony M. Brown</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">James H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Canestrari%2C+R">Rodolfo Canestrari</a>, <a href="/search/astro-ph?searchtype=author&query=Capasso%2C+M">Massimo Capasso</a>, <a href="/search/astro-ph?searchtype=author&query=Caprai%2C+M">Mirco Caprai</a>, <a href="/search/astro-ph?searchtype=author&query=Coppi%2C+P">Paolo Coppi</a>, <a href="/search/astro-ph?searchtype=author&query=Covault%2C+C+E">Corbin E. Covault</a>, <a href="/search/astro-ph?searchtype=author&query=Depaoli%2C+D">Davide Depaoli</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Venere%2C+L">Leonardo Di Venere</a> , et al. (64 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2203.08169v1-abstract-short" style="display: inline;"> The prototype Schwarzschild-Couder Telescope (pSCT) is a candidate for a medium-sized telescope in the Cherenkov Telescope Array. The pSCT is based on a novel dual mirror optics design which reduces the plate scale and allows for the use of silicon photomultipliers as photodetectors. The prototype pSCT camera currently has only the central sector instrumented with 25 camera modules (1600 pixels)… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.08169v1-abstract-full').style.display = 'inline'; document.getElementById('2203.08169v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2203.08169v1-abstract-full" style="display: none;"> The prototype Schwarzschild-Couder Telescope (pSCT) is a candidate for a medium-sized telescope in the Cherenkov Telescope Array. The pSCT is based on a novel dual mirror optics design which reduces the plate scale and allows for the use of silicon photomultipliers as photodetectors. The prototype pSCT camera currently has only the central sector instrumented with 25 camera modules (1600 pixels), providing a 2.68$^{\circ}$ field of view (FoV). The camera electronics are based on custom TARGET (TeV array readout with GSa/s sampling and event trigger) application specific integrated circuits. Field programmable gate arrays sample incoming signals at a gigasample per second. A single backplane provides camera-wide triggers. An upgrade of the pSCT camera is in progress, which will fully populate the focal plane. This will increase the number of pixels to 11,328, the number of backplanes to 9, and the FoV to 8.04$^{\circ}$. Here we give a detailed description of the pSCT camera, including the basic concept, mechanical design, detectors, electronics, current status and first light. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.08169v1-abstract-full').style.display = 'none'; document.getElementById('2203.08169v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> J. Astron. Telesc. Instrum. Syst. 8(1), 014007 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2110.13181">arXiv:2110.13181</a> <span> [<a href="https://arxiv.org/pdf/2110.13181">pdf</a>, <a href="https://arxiv.org/format/2110.13181">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ac32bd">10.3847/1538-4357/ac32bd <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Variability and Spectral Characteristics of Three Flaring Gamma-ray Quasars Observed by VERITAS and Fermi-LAT </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Adams%2C+C+B">C. B. Adams</a>, <a href="/search/astro-ph?searchtype=author&query=Batshoun%2C+J">J. Batshoun</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Brill%2C+A">A. Brill</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Capasso%2C+M">M. Capasso</a>, <a href="/search/astro-ph?searchtype=author&query=Cavins%2C+B">B. Cavins</a>, <a href="/search/astro-ph?searchtype=author&query=Christiansen%2C+J+L">J. L. Christiansen</a>, <a href="/search/astro-ph?searchtype=author&query=Coppi%2C+P">P. Coppi</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Farrell%2C+K+A">K. A Farrell</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+J+P">J. P. Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Foote%2C+G+M">G. M. Foote</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">A. Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Gent%2C+A">A. Gent</a>, <a href="/search/astro-ph?searchtype=author&query=Giuri%2C+C">C. Giuri</a>, <a href="/search/astro-ph?searchtype=author&query=Hanna%2C+D">D. Hanna</a>, <a href="/search/astro-ph?searchtype=author&query=Hassan%2C+T">T. Hassan</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">O. Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=Holder%2C+J">J. Holder</a>, <a href="/search/astro-ph?searchtype=author&query=Houck%2C+M">M. Houck</a>, <a href="/search/astro-ph?searchtype=author&query=Humensky%2C+T+B">T. B. Humensky</a>, <a href="/search/astro-ph?searchtype=author&query=Jin%2C+W">W. Jin</a> , et al. (41 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2110.13181v1-abstract-short" style="display: inline;"> Flat spectrum radio quasars (FSRQs) are the most luminous blazars at GeV energies, but only rarely emit detectable fluxes of TeV gamma rays, typically during bright GeV flares. We explore the gamma-ray variability and spectral characteristics of three FSRQs that have been observed at GeV and TeV energies by Fermi-LAT and VERITAS, making use of almost 100 hours of VERITAS observations spread over 1… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.13181v1-abstract-full').style.display = 'inline'; document.getElementById('2110.13181v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2110.13181v1-abstract-full" style="display: none;"> Flat spectrum radio quasars (FSRQs) are the most luminous blazars at GeV energies, but only rarely emit detectable fluxes of TeV gamma rays, typically during bright GeV flares. We explore the gamma-ray variability and spectral characteristics of three FSRQs that have been observed at GeV and TeV energies by Fermi-LAT and VERITAS, making use of almost 100 hours of VERITAS observations spread over 10 years: 3C 279, PKS 1222+216, and Ton 599. We explain the GeV flux distributions of the sources in terms of a model derived from a stochastic differential equation describing fluctuations in the magnetic field in the accretion disk, and estimate the timescales of magnetic flux accumulation and stochastic instabilities in their accretion disks. We identify distinct flares using a procedure based on Bayesian blocks and analyze their daily and sub-daily variability and gamma-ray energy spectra. Using observations from VERITAS as well as Fermi, Swift, and the Steward Observatory, we model the broadband spectral energy distributions of PKS 1222+216 and Ton 599 during VHE-detected flares in 2014 and 2017, respectively, strongly constraining the jet Doppler factors and gamma-ray emission region locations during these events. Finally, we place theoretical constraints on the potential production of PeV-scale neutrinos during these VHE flares. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.13181v1-abstract-full').style.display = 'none'; document.getElementById('2110.13181v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 October, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">34 pages, 13 figures. Accepted for publication in the Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2110.07463">arXiv:2110.07463</a> <span> [<a href="https://arxiv.org/pdf/2110.07463">pdf</a>, <a href="https://arxiv.org/format/2110.07463">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> </div> </div> <p class="title is-5 mathjax"> Prototype Schwarzschild-Couder Telescope for the Cherenkov Telescope Array: Commissioning the Optical System </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Adams%2C+C+B">C. B. Adams</a>, <a href="/search/astro-ph?searchtype=author&query=Ambrosi%2C+G">G. Ambrosi</a>, <a href="/search/astro-ph?searchtype=author&query=Ambrosio%2C+M">M. Ambrosio</a>, <a href="/search/astro-ph?searchtype=author&query=Aramo%2C+C">C. Aramo</a>, <a href="/search/astro-ph?searchtype=author&query=Batista%2C+P+I">P. I. Batista</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Bertucci%2C+B">B. Bertucci</a>, <a href="/search/astro-ph?searchtype=author&query=Bissaldi%2C+E">E. Bissaldi</a>, <a href="/search/astro-ph?searchtype=author&query=Bitossi%2C+M">M. Bitossi</a>, <a href="/search/astro-ph?searchtype=author&query=Boiano%2C+A">A. Boiano</a>, <a href="/search/astro-ph?searchtype=author&query=Bonavolont%C3%A0%2C+C">C. Bonavolont脿</a>, <a href="/search/astro-ph?searchtype=author&query=Bose%2C+R">R. Bose</a>, <a href="/search/astro-ph?searchtype=author&query=Brill%2C+A">A. Brill</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Cameron%2C+R+A">R. A. Cameron</a>, <a href="/search/astro-ph?searchtype=author&query=Canestrari%2C+R">R. Canestrari</a>, <a href="/search/astro-ph?searchtype=author&query=Capasso%2C+M">M. Capasso</a>, <a href="/search/astro-ph?searchtype=author&query=Caprai%2C+M">M. Caprai</a>, <a href="/search/astro-ph?searchtype=author&query=Covault%2C+C+E">C. E. Covault</a>, <a href="/search/astro-ph?searchtype=author&query=Depaoli%2C+D">D. Depaoli</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Venere%2C+L">L. Di Venere</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Fegan%2C+S">S. Fegan</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Fiandrini%2C+E">E. Fiandrini</a> , et al. (47 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2110.07463v1-abstract-short" style="display: inline;"> A prototype Schwarzschild-Couder Telescope (pSCT) has been constructed at the Fred Lawrence Whipple Observatory as a candidate for the medium-sized telescopes of the Cherenkov Telescope Array Observatory (CTAO). CTAO is currently entering early construction phase of the project and once completed it will vastly improve very high energy gamma-ray detection component in multi-wavelength and multi-me… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.07463v1-abstract-full').style.display = 'inline'; document.getElementById('2110.07463v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2110.07463v1-abstract-full" style="display: none;"> A prototype Schwarzschild-Couder Telescope (pSCT) has been constructed at the Fred Lawrence Whipple Observatory as a candidate for the medium-sized telescopes of the Cherenkov Telescope Array Observatory (CTAO). CTAO is currently entering early construction phase of the project and once completed it will vastly improve very high energy gamma-ray detection component in multi-wavelength and multi-messenger observations due to significantly improved sensitivity, angular resolution and field of view comparing to the current generation of the ground-based gamma-ray observatories H.E.S.S., MAGIC and VERITAS. The pSCT uses a dual aspheric mirror design with a $9.7$ m primary mirror and $5.4$ m secondary mirror, both of which are segmented. The Schwarzschild-Couder (SC) optical system (OS) selected for the prototype telescope achieves wide field of view of $8$ degrees and simultaneously reduces the focal plane plate scale allowing an unprecedented compact ($0.78$m diameter) implementation of the high-resolution camera ($6$mm/ $0.067$deg per imaging pixel with $11,328$ pixels) based on the silicon photo-multipliers (SiPMs). The OS of the telescope is designed to eliminate spherical and comatic aberrations and minimize astigmatism to radically improve off-axis imaging and consequently angular resolution across all the field of view with respect to the conventional single-mirror telescopes. Fast and high imaging resolution OS of the pSCT comes with the challenging submillimeter-precision custom alignment system, which was successfully demonstrated with an on-axis point spread function (PSF) of $2.9$ arcmin prior to the first-light detection of the Crab Nebula in 2020. Ongoing and future commissioning activities are reported. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.07463v1-abstract-full').style.display = 'none'; document.getElementById('2110.07463v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 October, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Proceedings of Science, PoS(ICRC2021)717 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2110.01075">arXiv:2110.01075</a> <span> [<a href="https://arxiv.org/pdf/2110.01075">pdf</a>, <a href="https://arxiv.org/format/2110.01075">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ac2c6a">10.3847/1538-4357/ac2c6a <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Multi-Wavelength Observation Campaign of the TeV Gamma-Ray Binary HESS J0632+057 with NuSTAR, VERITAS, MDM, and Swift </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Tokayer%2C+Y+M">Y. M. Tokayer</a>, <a href="/search/astro-ph?searchtype=author&query=An%2C+H">H. An</a>, <a href="/search/astro-ph?searchtype=author&query=Halpern%2C+J+P">J. P. Halpern</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+J">J. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Mori%2C+K">K. Mori</a>, <a href="/search/astro-ph?searchtype=author&query=Hailey%2C+C+J">C. J. Hailey</a>, <a href="/search/astro-ph?searchtype=author&query=Adams%2C+C+B">C. B. Adams</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Brill%2C+A">A. Brill</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Capasso%2C+M">M. Capasso</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">A. Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Farrell%2C+K+A">K. A Farrell</a>, <a href="/search/astro-ph?searchtype=author&query=Foote%2C+G+M">G. M Foote</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">A. Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Gent%2C+A">A. Gent</a>, <a href="/search/astro-ph?searchtype=author&query=Giuri%2C+C">C. Giuri</a>, <a href="/search/astro-ph?searchtype=author&query=Hanna%2C+D">D. Hanna</a>, <a href="/search/astro-ph?searchtype=author&query=Hassan%2C+T">T. Hassan</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">O. Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=Holder%2C+J">J. Holder</a>, <a href="/search/astro-ph?searchtype=author&query=Hona%2C+B">B. Hona</a>, <a href="/search/astro-ph?searchtype=author&query=Humensky%2C+T+B">T. B. Humensky</a> , et al. (31 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2110.01075v1-abstract-short" style="display: inline;"> HESS J0632+057 belongs to a rare subclass of binary systems which emits gamma-rays above 100 GeV. It stands out for its distinctive high-energy light curve, which features a sharp ``primary'' peak and broader ``secondary'' peak. We present the results of contemporaneous observations by NuSTAR and VERITAS during the secondary peak between Dec. 2019 and Feb. 2020, when the orbital phase ($蠁$) is bet… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.01075v1-abstract-full').style.display = 'inline'; document.getElementById('2110.01075v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2110.01075v1-abstract-full" style="display: none;"> HESS J0632+057 belongs to a rare subclass of binary systems which emits gamma-rays above 100 GeV. It stands out for its distinctive high-energy light curve, which features a sharp ``primary'' peak and broader ``secondary'' peak. We present the results of contemporaneous observations by NuSTAR and VERITAS during the secondary peak between Dec. 2019 and Feb. 2020, when the orbital phase ($蠁$) is between 0.55 and 0.75. NuSTAR detected X-ray spectral evolution, while VERITAS detected TeV emission. We fit a leptonic wind-collision model to the multi-wavelength spectra data obtained over the four NuSTAR and VERITAS observations, constraining the pulsar spin-down luminosity and the magnetization parameter at the shock. Despite long-term monitoring of the source from Oct. 2019 to Mar. 2020, the MDM observatory did not detect significant variation in H$伪$ and H$尾$ line equivalent widths, an expected signature of Be-disk interaction with the pulsar. Furthermore, fitting folded Swift-XRT light curve data with an intra-binary shock model constrained the orbital parameters, suggesting two orbital phases (at $蠁_D = 0.13$ and 0.37) where the pulsar crosses the Be-disk, as well as phases for the periastron ($蠁_0 = 0.30$) and inferior conjunction ($蠁_{\text{IFC}} = 0.75$). The broad-band X-ray spectra with Swift-XRT and NuSTAR allowed us to measure a higher neutral hydrogen column density at one of the predicted disk-passing phases. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.01075v1-abstract-full').style.display = 'none'; document.getElementById('2110.01075v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 October, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages, 9 figures, accepted to ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2109.11894">arXiv:2109.11894</a> <span> [<a href="https://arxiv.org/pdf/2109.11894">pdf</a>, <a href="https://arxiv.org/format/2109.11894">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ac29b7">10.3847/1538-4357/ac29b7 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observation of the gamma-ray binary HESS J0632+057 with the H.E.S.S., MAGIC, and VERITAS telescopes </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Adams%2C+C+B">C. B. Adams</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Brill%2C+A">A. Brill</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Capasso%2C+M">M. Capasso</a>, <a href="/search/astro-ph?searchtype=author&query=Chromey%2C+A+J">A. J. Chromey</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">A. Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Farrell%2C+K+A">K. A. Farrell</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+J+P">J P. Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Foote%2C+G">G. Foote</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">A. Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Gent%2C+A">A. Gent</a>, <a href="/search/astro-ph?searchtype=author&query=Gillanders%2C+G+H">G. H. Gillanders</a>, <a href="/search/astro-ph?searchtype=author&query=Giuri%2C+C">C. Giuri</a>, <a href="/search/astro-ph?searchtype=author&query=Gueta%2C+O">O. Gueta</a>, <a href="/search/astro-ph?searchtype=author&query=Hanna%2C+D">D. Hanna</a>, <a href="/search/astro-ph?searchtype=author&query=Hassan%2C+T">T. Hassan</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">O. Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=Holder%2C+J">J. Holder</a>, <a href="/search/astro-ph?searchtype=author&query=Hona%2C+B">B. Hona</a>, <a href="/search/astro-ph?searchtype=author&query=Humensky%2C+T+B">T. B. Humensky</a>, <a href="/search/astro-ph?searchtype=author&query=Jin%2C+W">W. Jin</a> , et al. (387 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2109.11894v1-abstract-short" style="display: inline;"> The results of gamma-ray observations of the binary system HESS J0632+057 collected during 450 hours over 15 years, between 2004 and 2019, are presented. Data taken with the atmospheric Cherenkov telescopes H.E.S.S., MAGIC, and VERITAS at energies above 350 GeV were used together with observations at X-ray energies obtained with Swift-XRT, Chandra, XMM-Newton, NuSTAR, and Suzaku. Some of these obs… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.11894v1-abstract-full').style.display = 'inline'; document.getElementById('2109.11894v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2109.11894v1-abstract-full" style="display: none;"> The results of gamma-ray observations of the binary system HESS J0632+057 collected during 450 hours over 15 years, between 2004 and 2019, are presented. Data taken with the atmospheric Cherenkov telescopes H.E.S.S., MAGIC, and VERITAS at energies above 350 GeV were used together with observations at X-ray energies obtained with Swift-XRT, Chandra, XMM-Newton, NuSTAR, and Suzaku. Some of these observations were accompanied by measurements of the H伪 emission line. A significant detection of the modulation of the VHE gamma-ray fluxes with a period of 316.7+-4.4 days is reported, consistent with the period of 317.3+-0.7 days obtained with a refined analysis of X-ray data. The analysis of data of four orbital cycles with dense observational coverage reveals short timescale variability, with flux-decay timescales of less than 20 days at very high energies. Flux variations observed over the time scale of several years indicate orbit-to-orbit variability. The analysis confirms the previously reported correlation of X-ray and gamma-ray emission from the system at very high significance, but can not find any correlation of optical H伪 parameters with X-ray or gamma-ray energy fluxes in simultaneous observations. The key finding is that the emission of HESS J0632+057 in the X-ray and gamma-ray energy bands is highly variable on different time scales. The ratio of gamma-ray to X-ray flux shows the equality or even dominance of the gamma-ray energy range. This wealth of new data is interpreted taking into account the insufficient knowledge of the ephemeris of the system, and discussed in the context of results reported on other gamma-ray binary systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.11894v1-abstract-full').style.display = 'none'; document.getElementById('2109.11894v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 September, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication by The Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2109.06225">arXiv:2109.06225</a> <span> [<a href="https://arxiv.org/pdf/2109.06225">pdf</a>, <a href="https://arxiv.org/format/2109.06225">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.22323/1.395.0830">10.22323/1.395.0830 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Detection of the Crab Nebula by the prototype Schwarzschild-Couder Telescope </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Adams%2C+C+B">C. B. Adams</a>, <a href="/search/astro-ph?searchtype=author&query=Ambrosi%2C+G">G. Ambrosi</a>, <a href="/search/astro-ph?searchtype=author&query=Ambrosio%2C+M">M. Ambrosio</a>, <a href="/search/astro-ph?searchtype=author&query=Aramo%2C+C">C. Aramo</a>, <a href="/search/astro-ph?searchtype=author&query=Batista%2C+P+I">P. I. Batista</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Bertucci%2C+B">B. Bertucci</a>, <a href="/search/astro-ph?searchtype=author&query=Bissaldi%2C+E">E. Bissaldi</a>, <a href="/search/astro-ph?searchtype=author&query=Bitossi%2C+M">M. Bitossi</a>, <a href="/search/astro-ph?searchtype=author&query=Boiano%2C+A">A. Boiano</a>, <a href="/search/astro-ph?searchtype=author&query=Bonavolont%C3%A0%2C+C">C. Bonavolont脿</a>, <a href="/search/astro-ph?searchtype=author&query=Bose%2C+R">R. Bose</a>, <a href="/search/astro-ph?searchtype=author&query=Brill%2C+A">A. Brill</a>, <a href="/search/astro-ph?searchtype=author&query=Brown%2C+A+M">A. M. Brown</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Cameron%2C+R+A">R. A. Cameron</a>, <a href="/search/astro-ph?searchtype=author&query=Canestrari%2C+R">R. Canestrari</a>, <a href="/search/astro-ph?searchtype=author&query=Capasso%2C+M">M. Capasso</a>, <a href="/search/astro-ph?searchtype=author&query=Caprai%2C+M">M. Caprai</a>, <a href="/search/astro-ph?searchtype=author&query=Covault%2C+C+E">C. E. Covault</a>, <a href="/search/astro-ph?searchtype=author&query=Depaoli%2C+D">D. Depaoli</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Venere%2C+L">L. Di Venere</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Fegan%2C+S">S. Fegan</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a> , et al. (49 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2109.06225v1-abstract-short" style="display: inline;"> The Schwarzschild-Couder Telescope (SCT) is a medium-sized telescope technology proposed for the Cherenkov Telescope Array. It uses a novel dual-mirror optical design that removes comatic aberrations across its entire field of view. The SCT camera employs high-resolution silicon photomultiplier (SiPM) sensors with a pixel size of 4 arcminutes. A prototype SCT (pSCT) has been constructed at the Fre… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.06225v1-abstract-full').style.display = 'inline'; document.getElementById('2109.06225v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2109.06225v1-abstract-full" style="display: none;"> The Schwarzschild-Couder Telescope (SCT) is a medium-sized telescope technology proposed for the Cherenkov Telescope Array. It uses a novel dual-mirror optical design that removes comatic aberrations across its entire field of view. The SCT camera employs high-resolution silicon photomultiplier (SiPM) sensors with a pixel size of 4 arcminutes. A prototype SCT (pSCT) has been constructed at the Fred Lawrence Whipple Observatory in Arizona, USA. An observing campaign in 2020, with a partial camera of 1600 pixels (2.7 degrees by 2.7 degrees field of view) resulted in detection of the Crab Nebula at 8.6 sigma statistical significance. Work on the pSCT camera and optical system is ongoing to improve performance and prepare for an upcoming camera upgrade. The pSCT camera upgrade will replace the current camera modules with improved SiPMs and readout electronics and will expand the camera to its full design field of view of 8 degrees in diameter (11,328 pixels). The fully upgraded pSCT will enable next-generation very-high-energy gamma-ray astrophysics through excellent background rejection and angular resolution. In this presentation we describe first results from the successful operation of the pSCT and future plans. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.06225v1-abstract-full').style.display = 'none'; document.getElementById('2109.06225v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 September, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 3 figures, 2 tables, contribution to ICRC 2021, similar to 10.1016/j.astropartphys.2021.102562 (arXiv:2012.08448)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Proceedings of Science, PoS(ICRC2021)830 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2109.05127">arXiv:2109.05127</a> <span> [<a href="https://arxiv.org/pdf/2109.05127">pdf</a>, <a href="https://arxiv.org/format/2109.05127">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.22323/1.395.0748">10.22323/1.395.0748 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Design and performance of the prototype Schwarzschild-Couder Telescope camera </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Adams%2C+C+B">C. B. Adams</a>, <a href="/search/astro-ph?searchtype=author&query=Ambrosi%2C+G">G. Ambrosi</a>, <a href="/search/astro-ph?searchtype=author&query=Ambrosio%2C+M">M. Ambrosio</a>, <a href="/search/astro-ph?searchtype=author&query=Aramo%2C+C">C. Aramo</a>, <a href="/search/astro-ph?searchtype=author&query=Batista%2C+P+I">P. I. Batista</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Bertucci%2C+B">B. Bertucci</a>, <a href="/search/astro-ph?searchtype=author&query=Bissaldi%2C+E">E. Bissaldi</a>, <a href="/search/astro-ph?searchtype=author&query=Bitossi%2C+M">M. Bitossi</a>, <a href="/search/astro-ph?searchtype=author&query=Boiano%2C+A">A. Boiano</a>, <a href="/search/astro-ph?searchtype=author&query=Bonavolonta%2C+C">C. Bonavolonta</a>, <a href="/search/astro-ph?searchtype=author&query=Bose%2C+R">R. Bose</a>, <a href="/search/astro-ph?searchtype=author&query=Brill%2C+A">A. Brill</a>, <a href="/search/astro-ph?searchtype=author&query=Brown%2C+A+M">A. M. Brown</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Cameron%2C+R+A">R. A. Cameron</a>, <a href="/search/astro-ph?searchtype=author&query=Capasso%2C+M">M. Capasso</a>, <a href="/search/astro-ph?searchtype=author&query=Caprai%2C+M">M. Caprai</a>, <a href="/search/astro-ph?searchtype=author&query=Covault%2C+C+E">C. E. Covault</a>, <a href="/search/astro-ph?searchtype=author&query=Depaoli%2C+D">D. Depaoli</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Venere%2C+L">L. Di Venere</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Fegan%2C+S">S. Fegan</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Fiandrini%2C+E">E. Fiandrini</a> , et al. (49 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2109.05127v1-abstract-short" style="display: inline;"> The Cherenkov Telescope Array (CTA) is the next-generation ground-based observatory for very-high-energy gamma-ray astronomy. An innovative 9.7 m aperture, dual-mirror Schwarzschild-Couder Telescope (SCT) design is a candidate design for CTA Medium-Sized Telescopes. A prototype SCT (pSCT) has been constructed at the Fred Lawrence Whipple Observatory in Arizona, USA. Its camera is currently partial… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.05127v1-abstract-full').style.display = 'inline'; document.getElementById('2109.05127v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2109.05127v1-abstract-full" style="display: none;"> The Cherenkov Telescope Array (CTA) is the next-generation ground-based observatory for very-high-energy gamma-ray astronomy. An innovative 9.7 m aperture, dual-mirror Schwarzschild-Couder Telescope (SCT) design is a candidate design for CTA Medium-Sized Telescopes. A prototype SCT (pSCT) has been constructed at the Fred Lawrence Whipple Observatory in Arizona, USA. Its camera is currently partially instrumented with 1600 pixels covering a field of view of 2.7 degrees square. The small plate scale of the optical system allows densely packed silicon photomultipliers to be used, which combined with high-density trigger and waveform readout electronics enable the high-resolution camera. The camera's electronics are capable of imaging air shower development at a rate of one billion samples per second. We describe the commissioning and performance of the pSCT camera, including trigger and waveform readout performance, calibration, and absolute GPS time stamping. We also present the upgrade to the camera, which is currently underway. The upgrade will fully populate the focal plane, increasing the field of view to 8 degree diameter, and lower the front-end electronics noise, enabling a lower trigger threshold and improved reconstruction and background rejection. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.05127v1-abstract-full').style.display = 'none'; document.getElementById('2109.05127v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 September, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 pages, 5 figures, Proceedings of the 37th International Cosmic Ray Conference (ICRC 2021), Berlin, Germany</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2109.05119">arXiv:2109.05119</a> <span>  </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> VERITAS contributions to the 37th International Cosmic Ray Conference </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Adams%2C+C+B">C. B. Adams</a>, <a href="/search/astro-ph?searchtype=author&query=Archer%2C+A">A. Archer</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Brill%2C+A">A. Brill</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Capasso%2C+M">M. Capasso</a>, <a href="/search/astro-ph?searchtype=author&query=Christiansen%2C+J+L">J. L. Christiansen</a>, <a href="/search/astro-ph?searchtype=author&query=Chromey%2C+A+J">A. J. Chromey</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">A. Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Farrell%2C+K+A">K. A. Farrell</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Foote%2C+G+M">G. M. Foote</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">A. Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Gent%2C+A">A. Gent</a>, <a href="/search/astro-ph?searchtype=author&query=Gillanders%2C+G+H">G. H. Gillanders</a>, <a href="/search/astro-ph?searchtype=author&query=Giuri%2C+C">C. Giuri</a>, <a href="/search/astro-ph?searchtype=author&query=Gueta%2C+O">O. Gueta</a>, <a href="/search/astro-ph?searchtype=author&query=Hanna%2C+D">D. Hanna</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">O. Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=Holder%2C+J">J. Holder</a>, <a href="/search/astro-ph?searchtype=author&query=Hona%2C+B">B. Hona</a>, <a href="/search/astro-ph?searchtype=author&query=Humensky%2C+T+B">T. B. Humensky</a>, <a href="/search/astro-ph?searchtype=author&query=Jin%2C+W">W. Jin</a> , et al. (36 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2109.05119v1-abstract-short" style="display: inline;"> Compilation of papers presented by the VERITAS Collaboration at the 37th International Cosmic Ray Conference (ICRC), held July 12 through July 23, 2021 (online) in Berlin, Germany. </span> <span class="abstract-full has-text-grey-dark mathjax" id="2109.05119v1-abstract-full" style="display: none;"> Compilation of papers presented by the VERITAS Collaboration at the 37th International Cosmic Ray Conference (ICRC), held July 12 through July 23, 2021 (online) in Berlin, Germany. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.05119v1-abstract-full').style.display = 'none'; document.getElementById('2109.05119v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 September, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">html page. 2021 ICRC, Berlin, Germany</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2108.09082">arXiv:2108.09082</a> <span> [<a href="https://arxiv.org/pdf/2108.09082">pdf</a>, <a href="https://arxiv.org/format/2108.09082">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.22323/1.395.0854">10.22323/1.395.0854 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The luminosity function of TeV-emitting BL Lacs: observations of an HBL sample with VERITAS </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Collaboration%2C+V">VERITAS Collaboration</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2108.09082v1-abstract-short" style="display: inline;"> High-frequency-peaked BL Lacs (HBLs) dominate the extragalactic TeV sky, with more than 50 objects detected by the current generation of TeV observatories. Still, the properties of TeV-emitting HBLs as a population are poorly understood due to biases introduced by the observing strategies of Cherenkov Telescopes, limiting our ability to estimate the potential contribution of TeV blazars to the dif… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.09082v1-abstract-full').style.display = 'inline'; document.getElementById('2108.09082v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2108.09082v1-abstract-full" style="display: none;"> High-frequency-peaked BL Lacs (HBLs) dominate the extragalactic TeV sky, with more than 50 objects detected by the current generation of TeV observatories. Still, the properties of TeV-emitting HBLs as a population are poorly understood due to biases introduced by the observing strategies of Cherenkov Telescopes, limiting our ability to estimate the potential contribution of TeV blazars to the diffuse neutrino, gamma-ray, and cosmic-ray background as well as their role in the late-stage evolution of active galactic nuclei. The VERITAS telescope array has designed a program to quantify and minimize observational biases by selecting a sample of 36 HBLs and measuring their TeV flux at times that are not weighted towards high-flux states. Such a survey could form the basis for a measurement of the luminosity function of TeV-emitting HBLs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.09082v1-abstract-full').style.display = 'none'; document.getElementById('2108.09082v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">in Proceedings of the 37th International Cosmic Ray Conference (ICRC 2021), Berlin, Germany</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2106.01386">arXiv:2106.01386</a> <span> [<a href="https://arxiv.org/pdf/2106.01386">pdf</a>, <a href="https://arxiv.org/format/2106.01386">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ac0623">10.3847/1538-4357/ac0623 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> An Archival Search for Neutron-Star Mergers in Gravitational Waves and Very-High-Energy Gamma Rays </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Adams%2C+C+B">C. B. Adams</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Brill%2C+A">A. Brill</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Capasso%2C+M">M. Capasso</a>, <a href="/search/astro-ph?searchtype=author&query=Christiansen%2C+J+L">J. L. Christiansen</a>, <a href="/search/astro-ph?searchtype=author&query=Chromey%2C+A+J">A. J. Chromey</a>, <a href="/search/astro-ph?searchtype=author&query=Daniel%2C+M+K">M. K. Daniel</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">A. Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Farrell%2C+K+A">K. A. Farrell</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+J+P">J. P. Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">A. Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Gent%2C+A">A. Gent</a>, <a href="/search/astro-ph?searchtype=author&query=Giuri%2C+C">C. Giuri</a>, <a href="/search/astro-ph?searchtype=author&query=Hanna%2C+D">D. Hanna</a>, <a href="/search/astro-ph?searchtype=author&query=Hassan%2C+T">T. Hassan</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">O. Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=Holder%2C+J">J. Holder</a>, <a href="/search/astro-ph?searchtype=author&query=Hughes%2C+G">G. Hughes</a>, <a href="/search/astro-ph?searchtype=author&query=Humensky%2C+T+B">T. B. Humensky</a>, <a href="/search/astro-ph?searchtype=author&query=Jin%2C+W">W. Jin</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">P. Kaaret</a> , et al. (37 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2106.01386v1-abstract-short" style="display: inline;"> The recent discovery of electromagnetic signals in coincidence with neutron-star mergers has solidified the importance of multimessenger campaigns in studying the most energetic astrophysical events. Pioneering multimessenger observatories, such as LIGO/Virgo and IceCube, record many candidate signals below the detection significance threshold. These sub-threshold event candidates are promising ta… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.01386v1-abstract-full').style.display = 'inline'; document.getElementById('2106.01386v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2106.01386v1-abstract-full" style="display: none;"> The recent discovery of electromagnetic signals in coincidence with neutron-star mergers has solidified the importance of multimessenger campaigns in studying the most energetic astrophysical events. Pioneering multimessenger observatories, such as LIGO/Virgo and IceCube, record many candidate signals below the detection significance threshold. These sub-threshold event candidates are promising targets for multimessenger studies, as the information provided by them may, when combined with contemporaneous gamma-ray observations, lead to significant detections. Here we describe a new method that uses such candidates to search for transient events using archival very-high-energy gamma-ray data from imaging atmospheric Cherenkov telescopes (IACTs). We demonstrate the application of this method to sub-threshold binary neutron star (BNS) merger candidates identified in Advanced LIGO's first observing run. We identify eight hours of archival VERITAS observations coincident with seven BNS merger candidates and search them for TeV emission. No gamma-ray emission is detected; we calculate upper limits on the integral flux and compare them to a short gamma-ray burst model. We anticipate this search method to serve as a starting point for IACT searches with future LIGO/Virgo data releases as well as in other sub-threshold studies for multimessenger transients, such as IceCube neutrinos. Furthermore, it can be deployed immediately with other current-generation IACTs, and has the potential for real-time use that places minimal burden on experimental operations. Lastly, this method may serve as a pilot for studies with the Cherenkov Telescope Array, which has the potential to observe even larger fields of view in its divergent pointing mode. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.01386v1-abstract-full').style.display = 'none'; document.getElementById('2106.01386v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 June, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2105.13911">arXiv:2105.13911</a> <span> [<a href="https://arxiv.org/pdf/2105.13911">pdf</a>, <a href="https://arxiv.org/format/2105.13911">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ac05b9">10.3847/1538-4357/ac05b9 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A Search for TeV Gamma-ray Emission from Pulsar Tails by VERITAS </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">Wystan Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Brill%2C+A">A. Brill</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J">James Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Capasso%2C+M">M Capasso</a>, <a href="/search/astro-ph?searchtype=author&query=Chromey%2C+A">A Chromey</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">Abraham Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Farrell%2C+K+A">K. A. Farrell</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Qi Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+J">J Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Foote%2C+G+M">G. M. Foote</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">Lucy Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">Amy Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Gent%2C+A">Alasdair Gent</a>, <a href="/search/astro-ph?searchtype=author&query=Giuri%2C+C">C Giuri</a>, <a href="/search/astro-ph?searchtype=author&query=Hanna%2C+D">David Hanna</a>, <a href="/search/astro-ph?searchtype=author&query=Hassan%2C+T">Tarek Hassan</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">Olivier Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=Holder%2C+J">Jamie Holder</a>, <a href="/search/astro-ph?searchtype=author&query=Hughes%2C+G">G Hughes</a>, <a href="/search/astro-ph?searchtype=author&query=Humensky%2C+T+B">T. B. Humensky</a>, <a href="/search/astro-ph?searchtype=author&query=Jin%2C+W">Weidong Jin</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">Philip Kaaret</a>, <a href="/search/astro-ph?searchtype=author&query=Kargaltsev%2C+O">Oleg Kargaltsev</a>, <a href="/search/astro-ph?searchtype=author&query=Kertzman%2C+M+P">Mary P. Kertzman</a> , et al. (34 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2105.13911v1-abstract-short" style="display: inline;"> We report on the search for very-high-energy gamma-ray emission from the regions around three nearby supersonic pulsars (PSR B0355+54, PSR J0357+3205 and PSR J1740+1000) that exhibit long X-ray tails. To date there is no clear detection of TeV emission from any pulsar tail that is prominent in X-ray or radio. We provide upper limits on the TeV flux, and luminosity, and also compare these limits wi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.13911v1-abstract-full').style.display = 'inline'; document.getElementById('2105.13911v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2105.13911v1-abstract-full" style="display: none;"> We report on the search for very-high-energy gamma-ray emission from the regions around three nearby supersonic pulsars (PSR B0355+54, PSR J0357+3205 and PSR J1740+1000) that exhibit long X-ray tails. To date there is no clear detection of TeV emission from any pulsar tail that is prominent in X-ray or radio. We provide upper limits on the TeV flux, and luminosity, and also compare these limits with other pulsar wind nebulae detected in X-rays and the tail emission model predictions. We find that at least one of the three tails is likely to be detected in observations that are a factor of 2-3 more sensitive. The analysis presented here also has implications for deriving the properties of pulsar tails, for those pulsars whose tails could be detected in TeV. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.13911v1-abstract-full').style.display = 'none'; document.getElementById('2105.13911v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 May, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages, 6 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2104.12735">arXiv:2104.12735</a> <span> [<a href="https://arxiv.org/pdf/2104.12735">pdf</a>, <a href="https://arxiv.org/format/2104.12735">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/abf926">10.3847/1538-4357/abf926 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> VERITAS Observations of the Galactic Center Region at Multi-TeV Gamma-Ray Energies </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Adams%2C+C+B">C. B. Adams</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Brill%2C+A">A. Brill</a>, <a href="/search/astro-ph?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/astro-ph?searchtype=author&query=Buchovecky%2C+M">M. Buchovecky</a>, <a href="/search/astro-ph?searchtype=author&query=Capasso%2C+M">M. Capasso</a>, <a href="/search/astro-ph?searchtype=author&query=Christiansen%2C+J+L">J. L. Christiansen</a>, <a href="/search/astro-ph?searchtype=author&query=Chromey%2C+A+J">A. J. Chromey</a>, <a href="/search/astro-ph?searchtype=author&query=Daniel%2C+M+K">M. K. Daniel</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">A. Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+J+P">J. P. Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">A. Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Gent%2C+A">A. Gent</a>, <a href="/search/astro-ph?searchtype=author&query=Gillanders%2C+G+H">G. H. Gillanders</a>, <a href="/search/astro-ph?searchtype=author&query=Giuri%2C+C">C. Giuri</a>, <a href="/search/astro-ph?searchtype=author&query=Hanna%2C+D">D. Hanna</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">O. Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=Holder%2C+J">J. Holder</a>, <a href="/search/astro-ph?searchtype=author&query=Hughes%2C+G">G. Hughes</a>, <a href="/search/astro-ph?searchtype=author&query=Humensky%2C+T+B">T. B. Humensky</a>, <a href="/search/astro-ph?searchtype=author&query=Jin%2C+W">W. Jin</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">P. Kaaret</a> , et al. (34 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2104.12735v1-abstract-short" style="display: inline;"> The Galactic Center (GC) region hosts a variety of powerful astronomical sources and rare astrophysical processes that emit a large flux of non-thermal radiation. The inner 375 pc x 600 pc region, called the Central Molecular Zone, is home to the supermassive black hole Sagittarius A*, massive cloud complexes, and particle accelerators such as supernova remnants. We present the results of our impr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.12735v1-abstract-full').style.display = 'inline'; document.getElementById('2104.12735v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2104.12735v1-abstract-full" style="display: none;"> The Galactic Center (GC) region hosts a variety of powerful astronomical sources and rare astrophysical processes that emit a large flux of non-thermal radiation. The inner 375 pc x 600 pc region, called the Central Molecular Zone, is home to the supermassive black hole Sagittarius A*, massive cloud complexes, and particle accelerators such as supernova remnants. We present the results of our improved analysis of the very-high-energy (VHE) gamma-ray emission above 2 TeV from the GC using 125 hours of data taken with the VERITAS imaging-atmospheric Cherenkov telescope between 2010 and 2018. The central source VER J1745-290, consistent with the position of Sagittarius A*, is detected at a significance of 38 standard deviations above the background level $(38蟽)$, and we report its spectrum and light curve. Its differential spectrum is consistent with a power law with exponential cutoff, with a spectral index of $2.12^{+0.22}_{-0.17}$, a flux normalization at 5.3 TeV of $1.27^{+0.22}_{-0.23}\times 10^{-13}$ TeV-1 cm-2 s-1, and cutoff energy of $10.0^{+4.0}_{-2.0}$ TeV. We also present results on the diffuse emission near the GC, obtained by combining data from multiple regions along the GC ridge which yield a cumulative significance of $9.5蟽$. The diffuse GC ridge spectrum is best fit by a power law with a hard index of 2.19 $\pm$ 0.20, showing no evidence of a cutoff up to 40 TeV. This strengthens the evidence for a potential accelerator of PeV cosmic rays being present in the GC. We also provide spectra of the other sources in our field of view with significant detections, composite supernova remnant G0.9+0.1 and HESS J1746-285. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.12735v1-abstract-full').style.display = 'none'; document.getElementById('2104.12735v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 April, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 8 figures, Accepted for publication in Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2012.08448">arXiv:2012.08448</a> <span> [<a href="https://arxiv.org/pdf/2012.08448">pdf</a>, <a href="https://arxiv.org/format/2012.08448">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.astropartphys.2021.102562">10.1016/j.astropartphys.2021.102562 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Detection of the Crab Nebula with the 9.7 m Prototype Schwarzschild-Couder Telescope </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Adams%2C+C+B">C. B. Adams</a>, <a href="/search/astro-ph?searchtype=author&query=Alfaro%2C+R">R. Alfaro</a>, <a href="/search/astro-ph?searchtype=author&query=Ambrosi%2C+G">G. Ambrosi</a>, <a href="/search/astro-ph?searchtype=author&query=Ambrosio%2C+M">M. Ambrosio</a>, <a href="/search/astro-ph?searchtype=author&query=Aramo%2C+C">C. Aramo</a>, <a href="/search/astro-ph?searchtype=author&query=Arlen%2C+T">T. Arlen</a>, <a href="/search/astro-ph?searchtype=author&query=Batista%2C+P+I">P. I. Batista</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Bertucci%2C+B">B. Bertucci</a>, <a href="/search/astro-ph?searchtype=author&query=Bissaldi%2C+E">E. Bissaldi</a>, <a href="/search/astro-ph?searchtype=author&query=Biteau%2C+J">J. Biteau</a>, <a href="/search/astro-ph?searchtype=author&query=Bitossi%2C+M">M. Bitossi</a>, <a href="/search/astro-ph?searchtype=author&query=Boiano%2C+A">A. Boiano</a>, <a href="/search/astro-ph?searchtype=author&query=Bonavolont%C3%A0%2C+C">C. Bonavolont脿</a>, <a href="/search/astro-ph?searchtype=author&query=Bose%2C+R">R. Bose</a>, <a href="/search/astro-ph?searchtype=author&query=Bouvier%2C+A">A. Bouvier</a>, <a href="/search/astro-ph?searchtype=author&query=Brill%2C+A">A. Brill</a>, <a href="/search/astro-ph?searchtype=author&query=Brown%2C+A+M">A. M. Brown</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Byrum%2C+K">K. Byrum</a>, <a href="/search/astro-ph?searchtype=author&query=Cameron%2C+R+A">R. A. Cameron</a>, <a href="/search/astro-ph?searchtype=author&query=Canestrari%2C+R">R. Canestrari</a>, <a href="/search/astro-ph?searchtype=author&query=Capasso%2C+M">M. Capasso</a>, <a href="/search/astro-ph?searchtype=author&query=Caprai%2C+M">M. Caprai</a>, <a href="/search/astro-ph?searchtype=author&query=Covault%2C+C+E">C. E. Covault</a> , et al. (83 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2012.08448v1-abstract-short" style="display: inline;"> The Schwarzschild-Couder Telescope (SCT) is a telescope concept proposed for the Cherenkov Telescope Array. It employs a dual-mirror optical design to remove comatic aberrations over an $8^{\circ}$ field of view, and a high-density silicon photomultiplier camera (with a pixel resolution of 4 arcmin) to record Cherenkov emission from cosmic ray and gamma-ray initiated particle cascades in the atmos… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.08448v1-abstract-full').style.display = 'inline'; document.getElementById('2012.08448v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2012.08448v1-abstract-full" style="display: none;"> The Schwarzschild-Couder Telescope (SCT) is a telescope concept proposed for the Cherenkov Telescope Array. It employs a dual-mirror optical design to remove comatic aberrations over an $8^{\circ}$ field of view, and a high-density silicon photomultiplier camera (with a pixel resolution of 4 arcmin) to record Cherenkov emission from cosmic ray and gamma-ray initiated particle cascades in the atmosphere. The prototype SCT (pSCT), comprising a 9.7 m diameter primary mirror and a partially instrumented camera with 1536 pixels, has been constructed at the Fred Lawrence Whipple Observatory. The telescope was inaugurated in January 2019, with commissioning continuing throughout 2019. We describe the first campaign of observations with the pSCT, conducted in January and February of 2020, and demonstrate the detection of gamma-ray emission from the Crab Nebula with a statistical significance of $8.6蟽$. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.08448v1-abstract-full').style.display = 'none'; document.getElementById('2012.08448v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 December, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 12 figures, 3 tables, submitted to Astroparticle Physics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2010.10608">arXiv:2010.10608</a> <span> [<a href="https://arxiv.org/pdf/2010.10608">pdf</a>, <a href="https://arxiv.org/format/2010.10608">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.astropartphys.2020.102529">10.1016/j.astropartphys.2020.102529 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> XL-Calibur -- a second-generation balloon-borne hard X-ray polarimetry mission </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Abarr%2C+Q">Q. Abarr</a>, <a href="/search/astro-ph?searchtype=author&query=Awaki%2C+H">H. Awaki</a>, <a href="/search/astro-ph?searchtype=author&query=Baring%2C+M+G">M. G. Baring</a>, <a href="/search/astro-ph?searchtype=author&query=Bose%2C+R">R. Bose</a>, <a href="/search/astro-ph?searchtype=author&query=De+Geronimo%2C+G">G. De Geronimo</a>, <a href="/search/astro-ph?searchtype=author&query=Dowkontt%2C+P">P. Dowkontt</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Guarino%2C+V">V. Guarino</a>, <a href="/search/astro-ph?searchtype=author&query=Hattori%2C+K">K. Hattori</a>, <a href="/search/astro-ph?searchtype=author&query=Hayashida%2C+K">K. Hayashida</a>, <a href="/search/astro-ph?searchtype=author&query=Imazato%2C+F">F. Imazato</a>, <a href="/search/astro-ph?searchtype=author&query=Ishida%2C+M">M. Ishida</a>, <a href="/search/astro-ph?searchtype=author&query=Iyer%2C+N+K">N. K. Iyer</a>, <a href="/search/astro-ph?searchtype=author&query=Kislat%2C+F">F. Kislat</a>, <a href="/search/astro-ph?searchtype=author&query=Kiss%2C+M">M. Kiss</a>, <a href="/search/astro-ph?searchtype=author&query=Kitaguchi%2C+T">T. Kitaguchi</a>, <a href="/search/astro-ph?searchtype=author&query=Krawczynski%2C+H">H. Krawczynski</a>, <a href="/search/astro-ph?searchtype=author&query=Lisalda%2C+L">L. Lisalda</a>, <a href="/search/astro-ph?searchtype=author&query=Matake%2C+H">H. Matake</a>, <a href="/search/astro-ph?searchtype=author&query=Maeda%2C+Y">Y. Maeda</a>, <a href="/search/astro-ph?searchtype=author&query=Matsumoto%2C+H">H. Matsumoto</a>, <a href="/search/astro-ph?searchtype=author&query=Mineta%2C+T">T. Mineta</a>, <a href="/search/astro-ph?searchtype=author&query=Miyazawa%2C+T">T. Miyazawa</a>, <a href="/search/astro-ph?searchtype=author&query=Mizuno%2C+T">T. Mizuno</a>, <a href="/search/astro-ph?searchtype=author&query=Okajima%2C+T">T. Okajima</a> , et al. (16 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2010.10608v1-abstract-short" style="display: inline;"> XL-Calibur is a hard X-ray (15-80 keV) polarimetry mission operating from a stabilised balloon-borne platform in the stratosphere. It builds on heritage from the X-Calibur mission, which observed the accreting neutron star GX 301-2 from Antarctica, between December 29th 2018 and January 1st 2019. The XL-Calibur design incorporates an X-ray mirror, which focusses X-rays onto a polarimeter comprisin… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2010.10608v1-abstract-full').style.display = 'inline'; document.getElementById('2010.10608v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2010.10608v1-abstract-full" style="display: none;"> XL-Calibur is a hard X-ray (15-80 keV) polarimetry mission operating from a stabilised balloon-borne platform in the stratosphere. It builds on heritage from the X-Calibur mission, which observed the accreting neutron star GX 301-2 from Antarctica, between December 29th 2018 and January 1st 2019. The XL-Calibur design incorporates an X-ray mirror, which focusses X-rays onto a polarimeter comprising a beryllium rod surrounded by Cadmium Zinc Telluride (CZT) detectors. The polarimeter is housed in an anticoincidence shield to mitigate background from particles present in the stratosphere. The mirror and polarimeter-shield assembly are mounted at opposite ends of a 12 m long lightweight truss, which is pointed with arcsecond precision by WASP - the Wallops Arc Second Pointer. The XL-Calibur mission will achieve a substantially improved sensitivity over X-Calibur by using a larger effective area X-ray mirror, reducing background through thinner CZT detectors, and improved anticoincidence shielding. When observing a 1 Crab source for $t_{\rm day}$ days, the Minimum Detectable Polarisation (at 99% confidence level) is $\sim$2$\%\cdot t_{\rm day}^{-1/2}$. The energy resolution at 40 keV is $\sim$5.9 keV. The aim of this paper is to describe the design and performance of the XL-Calibur mission, as well as the foreseen science programme. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2010.10608v1-abstract-full').style.display = 'none'; document.getElementById('2010.10608v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 October, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 17 figures. Accepted for publication in Astroparticle Physics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2005.03110">arXiv:2005.03110</a> <span> [<a href="https://arxiv.org/pdf/2005.03110">pdf</a>, <a href="https://arxiv.org/format/2005.03110">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ab910e">10.3847/1538-4357/ab910e <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> VERITAS Discovery of VHE Emission from the Radio Galaxy 3C 264: A Multi-Wavelength Study </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Archer%2C+A">A. Archer</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Bird%2C+R">R. Bird</a>, <a href="/search/astro-ph?searchtype=author&query=Brill%2C+A">A. Brill</a>, <a href="/search/astro-ph?searchtype=author&query=Buchovecky%2C+M">M. Buchovecky</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Carini%2C+M+T">M. T. Carini</a>, <a href="/search/astro-ph?searchtype=author&query=Christiansen%2C+J+L">J. L. Christiansen</a>, <a href="/search/astro-ph?searchtype=author&query=Chromey%2C+A+J">A. J. Chromey</a>, <a href="/search/astro-ph?searchtype=author&query=Daniel%2C+M+K">M. K. Daniel</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">A. Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Fortin%2C+P">P. Fortin</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">A. Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Gent%2C+A">A. Gent</a>, <a href="/search/astro-ph?searchtype=author&query=Georganopoulos%2C+M">M. Georganopoulos</a>, <a href="/search/astro-ph?searchtype=author&query=Gillanders%2C+G+H">G. H. Gillanders</a>, <a href="/search/astro-ph?searchtype=author&query=Giuri%2C+C">C. Giuri</a>, <a href="/search/astro-ph?searchtype=author&query=Gueta%2C+O">O. Gueta</a>, <a href="/search/astro-ph?searchtype=author&query=Hanna%2C+D">D. Hanna</a>, <a href="/search/astro-ph?searchtype=author&query=Hassan%2C+T">T. Hassan</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">O. Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=Holder%2C+J">J. Holder</a> , et al. (45 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2005.03110v1-abstract-short" style="display: inline;"> The radio source 3C 264, hosted by the giant elliptical galaxy NGC 3862, was observed with VERITAS between February 2017 and May 2019. These deep observations resulted in the discovery of very-high-energy (VHE; E $>100$ GeV) $纬$-ray emission from this active galaxy. An analysis of $\sim$57 hours of quality-selected live time yields a detection at the position of the source, corresponding to a stat… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2005.03110v1-abstract-full').style.display = 'inline'; document.getElementById('2005.03110v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2005.03110v1-abstract-full" style="display: none;"> The radio source 3C 264, hosted by the giant elliptical galaxy NGC 3862, was observed with VERITAS between February 2017 and May 2019. These deep observations resulted in the discovery of very-high-energy (VHE; E $>100$ GeV) $纬$-ray emission from this active galaxy. An analysis of $\sim$57 hours of quality-selected live time yields a detection at the position of the source, corresponding to a statistical significance of 7.8 standard deviations above background. The observed VHE flux is variable on monthly time scales, with an elevated flux seen in 2018 observations. The VHE emission during this elevated state is well-characterized by a power-law spectrum with a photon index $螕= 2.20 \pm 0.27$ and flux F($>315$ GeV) = ($7.6\pm 1.2_{\mathrm stat} \pm 2.3_{\mathrm syst})\times 10^{-13}$ cm$^{-2}$ s$^{-1}$, or approximately 0.7% of the Crab Nebula flux above the same threshold. 3C 264 ($z = 0.0217$) is the most distant radio galaxy detected at VHE, and the elevated state is thought to be similar to that of the famously outbursting jet in M 87. Consequently, extensive contemporaneous multi-wavelength data were acquired in 2018 at the time of the VHE high state. An analysis of these data, including VLBA, VLA, HST, Chandra and Swift observations in addition to the VERITAS data, is presented, along with a discussion of the resulting spectral energy distribution. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2005.03110v1-abstract-full').style.display = 'none'; document.getElementById('2005.03110v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 May, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 11 figures, Accepted for publication in Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2001.03581">arXiv:2001.03581</a> <span> [<a href="https://arxiv.org/pdf/2001.03581">pdf</a>, <a href="https://arxiv.org/format/2001.03581">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ab672c">10.3847/1538-4357/ab672c <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observations of a GX 301-2 Apastron Flare with the X-Calibur Hard X-Ray Polarimeter Supported by NICER, the Swift XRT and BAT, and Fermi GBM </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Abarr%2C+Q">Q. Abarr</a>, <a href="/search/astro-ph?searchtype=author&query=Baring%2C+M">M. Baring</a>, <a href="/search/astro-ph?searchtype=author&query=Beheshtipour%2C+B">B. Beheshtipour</a>, <a href="/search/astro-ph?searchtype=author&query=Beilicke%2C+M">M. Beilicke</a>, <a href="/search/astro-ph?searchtype=author&query=deGeronimo%2C+G">G. deGeronimo</a>, <a href="/search/astro-ph?searchtype=author&query=Dowkontt%2C+P">P. Dowkontt</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Guarino%2C+V">V. Guarino</a>, <a href="/search/astro-ph?searchtype=author&query=Iyer%2C+N">N. Iyer</a>, <a href="/search/astro-ph?searchtype=author&query=Kislat%2C+F">F. Kislat</a>, <a href="/search/astro-ph?searchtype=author&query=Kiss%2C+M">M. Kiss</a>, <a href="/search/astro-ph?searchtype=author&query=Kitaguchi%2C+T">T. Kitaguchi</a>, <a href="/search/astro-ph?searchtype=author&query=Krawczynski%2C+H">H. Krawczynski</a>, <a href="/search/astro-ph?searchtype=author&query=Lanzi%2C+J">J. Lanzi</a>, <a href="/search/astro-ph?searchtype=author&query=Li%2C+S">S. Li</a>, <a href="/search/astro-ph?searchtype=author&query=Lisalda%2C+L">L. Lisalda</a>, <a href="/search/astro-ph?searchtype=author&query=Okajima%2C+T">T. Okajima</a>, <a href="/search/astro-ph?searchtype=author&query=Pearce%2C+M">M. Pearce</a>, <a href="/search/astro-ph?searchtype=author&query=Press%2C+L">L. Press</a>, <a href="/search/astro-ph?searchtype=author&query=Rauch%2C+B">B. Rauch</a>, <a href="/search/astro-ph?searchtype=author&query=Stuchlik%2C+D">D. Stuchlik</a>, <a href="/search/astro-ph?searchtype=author&query=Takahashi%2C+H">H. Takahashi</a>, <a href="/search/astro-ph?searchtype=author&query=Tang%2C+J">J. Tang</a>, <a href="/search/astro-ph?searchtype=author&query=Uchida%2C+N">N. Uchida</a>, <a href="/search/astro-ph?searchtype=author&query=West%2C+A">A. West</a> , et al. (6 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2001.03581v1-abstract-short" style="display: inline;"> The accretion-powered X-ray pulsar GX 301-2 was observed with the balloon-borne X-Calibur hard X-ray polarimeter during late December 2018, with contiguous observations by the NICER X-ray telescope, the Swift X-ray Telescope and Burst Alert Telescope, and the Fermi Gamma-ray Burst Monitor spanning several months. The observations detected the pulsar in a rare apastron flaring state coinciding with… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2001.03581v1-abstract-full').style.display = 'inline'; document.getElementById('2001.03581v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2001.03581v1-abstract-full" style="display: none;"> The accretion-powered X-ray pulsar GX 301-2 was observed with the balloon-borne X-Calibur hard X-ray polarimeter during late December 2018, with contiguous observations by the NICER X-ray telescope, the Swift X-ray Telescope and Burst Alert Telescope, and the Fermi Gamma-ray Burst Monitor spanning several months. The observations detected the pulsar in a rare apastron flaring state coinciding with a significant spin-up of the pulsar discovered with the Fermi GBM. The X-Calibur, NICER, and Swift observations reveal a pulse profile strongly dominated by one main peak, and the NICER and Swift data show strong variation of the profile from pulse to pulse. The X-Calibur observations constrain for the first time the linear polarization of the 15-35 keV emission from a highly magnetized accreting neutron star, indicating a polarization degree of (27+38-27)% (90% confidence limit) averaged over all pulse phases. We discuss the spin-up and the X-ray spectral and polarimetric results in the context of theoretical predictions. We conclude with a discussion of the scientific potential of future observations of highly magnetized neutron stars with the more sensitive follow-up mission XL-Calibur. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2001.03581v1-abstract-full').style.display = 'none'; document.getElementById('2001.03581v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 January, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in the Astrophysical Journal. 20 pages, 19 figures, 4 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1811.05774">arXiv:1811.05774</a> <span> [<a href="https://arxiv.org/pdf/1811.05774">pdf</a>, <a href="https://arxiv.org/format/1811.05774">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Novel Search for TeV-Initiated Pair Cascades in the Intergalactic Medium </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Chen%2C+W">Wenlei Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">James H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Ferrer%2C+F">Francesc Ferrer</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1811.05774v1-abstract-short" style="display: inline;"> TeV emission from blazars can be used to probe the intergalactic magnetic fields and measure their intensity, coherence length, and helicity. Intergalactic magnetic fields deflect the electron-positron pairs produced by very-high-energy gamma-rays from blazars, resulting in broadened beams of cascade gamma-rays developing along the projected direction of the blazar jet. We present an analysis that… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1811.05774v1-abstract-full').style.display = 'inline'; document.getElementById('1811.05774v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1811.05774v1-abstract-full" style="display: none;"> TeV emission from blazars can be used to probe the intergalactic magnetic fields and measure their intensity, coherence length, and helicity. Intergalactic magnetic fields deflect the electron-positron pairs produced by very-high-energy gamma-rays from blazars, resulting in broadened beams of cascade gamma-rays developing along the projected direction of the blazar jet. We present an analysis that uses for the first time the jet orientation of 12 high-synchrotron-peaked (HSP) BL~Lac-type blazars from VLBA radio observations to search for signatures of pair haloes in the Fermi-LAT data. Our search improves the sensitivity of previous studies by taking the asymmetry of the pair haloes into account, increasing the signal to noise and reducing the possibility of systematics in determining the point spread function. Although there is no significant detection, a hint for an offset halo with a global significance of 2$蟽$ is found in the $30-300$ GeV energy range, corresponding to an intergalactic magnetic field with $\sim 10^{-15}$ Gauss, consistent with the inferred field from a prior study using stacked HSP BL Lac objects. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1811.05774v1-abstract-full').style.display = 'none'; document.getElementById('1811.05774v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 November, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2018. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1803.01266">arXiv:1803.01266</a> <span> [<a href="https://arxiv.org/pdf/1803.01266">pdf</a>, <a href="https://arxiv.org/format/1803.01266">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/aab371">10.3847/1538-4357/aab371 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A strong limit on the very-high-energy emission from GRB 150323A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Abeysekara%2C+A+U">A. U. Abeysekara</a>, <a href="/search/astro-ph?searchtype=author&query=Archer%2C+A">A. Archer</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Bird%2C+R">R. Bird</a>, <a href="/search/astro-ph?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/astro-ph?searchtype=author&query=Buchovecky%2C+M">M. Buchovecky</a>, <a href="/search/astro-ph?searchtype=author&query=Bugaev%2C+V">V. Bugaev</a>, <a href="/search/astro-ph?searchtype=author&query=Connolly%2C+M+P">M. P. Connolly</a>, <a href="/search/astro-ph?searchtype=author&query=Cui%2C+W">W. Cui</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">A. Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+J+P">J. P. Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Flinders%2C+A">A. Flinders</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">A. Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Gillanders%2C+G+H">G. H. Gillanders</a>, <a href="/search/astro-ph?searchtype=author&query=H%C3%BCtten%2C+M">M. H眉tten</a>, <a href="/search/astro-ph?searchtype=author&query=Hanna%2C+D">D. Hanna</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">O. Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=Holder%2C+J">J. Holder</a>, <a href="/search/astro-ph?searchtype=author&query=Hughes%2C+G">G. Hughes</a>, <a href="/search/astro-ph?searchtype=author&query=Humensky%2C+T+B">T. B. Humensky</a>, <a href="/search/astro-ph?searchtype=author&query=Johnson%2C+C+A">C. A. Johnson</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">P. Kaaret</a> , et al. (41 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1803.01266v1-abstract-short" style="display: inline;"> On 2015 March 23, VERITAS responded to a $Swift$-BAT detection of a gamma-ray burst, with observations beginning 270 seconds after the onset of BAT emission, and only 135 seconds after the main BAT emission peak. No statistically significant signal is detected above 140 GeV. The VERITAS upper limit on the fluence in a 40 minute integration corresponds to about 1% of the prompt fluence. Our limit i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1803.01266v1-abstract-full').style.display = 'inline'; document.getElementById('1803.01266v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1803.01266v1-abstract-full" style="display: none;"> On 2015 March 23, VERITAS responded to a $Swift$-BAT detection of a gamma-ray burst, with observations beginning 270 seconds after the onset of BAT emission, and only 135 seconds after the main BAT emission peak. No statistically significant signal is detected above 140 GeV. The VERITAS upper limit on the fluence in a 40 minute integration corresponds to about 1% of the prompt fluence. Our limit is particularly significant since the very-high-energy (VHE) observation started only $\sim$2 minutes after the prompt emission peaked, and $Fermi$-LAT observations of numerous other bursts have revealed that the high-energy emission is typically delayed relative to the prompt radiation and lasts significantly longer. Also, the proximity of GRB~150323A ($z=0.593$) limits the attenuation by the extragalactic background light to $\sim 50$ % at 100-200 GeV. We conclude that GRB 150323A had an intrinsically very weak high-energy afterglow, or that the GeV spectrum had a turnover below $\sim100$ GeV. If the GRB exploded into the stellar wind of a massive progenitor, the VHE non-detection constrains the wind density parameter to be $A\gtrsim 3\times 10^{11}$ g cm$^{-1}$, consistent with a standard Wolf-Rayet progenitor. Alternatively, the VHE emission from the blast wave would be weak in a very tenuous medium such as the ISM, which therefore cannot be ruled out as the environment of GRB 150323A. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1803.01266v1-abstract-full').style.display = 'none'; document.getElementById('1803.01266v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 March, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 1 figure. Accepted for publication in The Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1703.01307">arXiv:1703.01307</a> <span> [<a href="https://arxiv.org/pdf/1703.01307">pdf</a>, <a href="https://arxiv.org/format/1703.01307">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.astropartphys.2017.03.001">10.1016/j.astropartphys.2017.03.001 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Gamma-ray Observations Under Bright Moonlight with VERITAS </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Archambault%2C+S">S. Archambault</a>, <a href="/search/astro-ph?searchtype=author&query=Archer%2C+A">A. Archer</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Bird%2C+R">R. Bird</a>, <a href="/search/astro-ph?searchtype=author&query=Bourbeau%2C+E">E. Bourbeau</a>, <a href="/search/astro-ph?searchtype=author&query=Bouvier%2C+A">A. Bouvier</a>, <a href="/search/astro-ph?searchtype=author&query=Buchovecky%2C+M">M. Buchovecky</a>, <a href="/search/astro-ph?searchtype=author&query=Bugaev%2C+V">V. Bugaev</a>, <a href="/search/astro-ph?searchtype=author&query=Cardenzana%2C+J+V">J. V Cardenzana</a>, <a href="/search/astro-ph?searchtype=author&query=Cerruti%2C+M">M. Cerruti</a>, <a href="/search/astro-ph?searchtype=author&query=Ciupik%2C+L">L. Ciupik</a>, <a href="/search/astro-ph?searchtype=author&query=Connolly%2C+M+P">M. P. Connolly</a>, <a href="/search/astro-ph?searchtype=author&query=Cui%2C+W">W. Cui</a>, <a href="/search/astro-ph?searchtype=author&query=Daniel%2C+M+K">M. K. Daniel</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">A. Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+J+P">J. P. Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Fleischhack%2C+H">H. Fleischhack</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">A. Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Gillanders%2C+G+H">G. H. Gillanders</a>, <a href="/search/astro-ph?searchtype=author&query=Griffin%2C+S">S. Griffin</a>, <a href="/search/astro-ph?searchtype=author&query=Hanna%2C+D">D. Hanna</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">O. Hervet</a> , et al. (40 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1703.01307v1-abstract-short" style="display: inline;"> Imaging atmospheric Cherenkov telescopes (IACTs) are equipped with sensitive photomultiplier tube (PMT) cameras. Exposure to high levels of background illumination degrades the efficiency of and potentially destroys these photo-detectors over time, so IACTs cannot be operated in the same configuration in the presence of bright moonlight as under dark skies. Since September 2012, observations have… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.01307v1-abstract-full').style.display = 'inline'; document.getElementById('1703.01307v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1703.01307v1-abstract-full" style="display: none;"> Imaging atmospheric Cherenkov telescopes (IACTs) are equipped with sensitive photomultiplier tube (PMT) cameras. Exposure to high levels of background illumination degrades the efficiency of and potentially destroys these photo-detectors over time, so IACTs cannot be operated in the same configuration in the presence of bright moonlight as under dark skies. Since September 2012, observations have been carried out with the VERITAS IACTs under bright moonlight (defined as about three times the night-sky-background (NSB) of a dark extragalactic field, typically occurring when Moon illumination > 35%) in two observing modes, firstly by reducing the voltage applied to the PMTs and, secondly, with the addition of ultra-violet (UV) bandpass filters to the cameras. This has allowed observations at up to about 30 times previous NSB levels (around 80% Moon illumination), resulting in 30% more observing time between the two modes over the course of a year. These additional observations have already allowed for the detection of a flare from the 1ES 1727+502 and for an observing program targeting a measurement of the cosmic-ray positron fraction. We provide details of these new observing modes and their performance relative to the standard VERITAS observations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.01307v1-abstract-full').style.display = 'none'; document.getElementById('1703.01307v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 March, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2017. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1701.06740">arXiv:1701.06740</a> <span> [<a href="https://arxiv.org/pdf/1701.06740">pdf</a>, <a href="https://arxiv.org/format/1701.06740">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/836/1/23">10.3847/1538-4357/836/1/23 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Gamma-ray observations of Tycho's SNR with VERITAS and Fermi </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=VERITAS+Collaboration"> VERITAS Collaboration</a>, <a href="/search/astro-ph?searchtype=author&query=Archambault%2C+S">S. Archambault</a>, <a href="/search/astro-ph?searchtype=author&query=Archer%2C+A">A. Archer</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Bird%2C+R">R. Bird</a>, <a href="/search/astro-ph?searchtype=author&query=Bourbeau%2C+E">E. Bourbeau</a>, <a href="/search/astro-ph?searchtype=author&query=Buchovecky%2C+M">M. Buchovecky</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Bugaev%2C+V">V. Bugaev</a>, <a href="/search/astro-ph?searchtype=author&query=Cerruti%2C+M">M. Cerruti</a>, <a href="/search/astro-ph?searchtype=author&query=Connolly%2C+M+P">M. P. Connolly</a>, <a href="/search/astro-ph?searchtype=author&query=Cui%2C+W">W. Cui</a>, <a href="/search/astro-ph?searchtype=author&query=Dwarkadas%2C+V+V">V. V. Dwarkadas</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">A. Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+J+P">J. P. Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Fleischhack%2C+H">H. Fleischhack</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">A. Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Griffin%2C+S">S. Griffin</a>, <a href="/search/astro-ph?searchtype=author&query=H%7Futten%2C+M">M. Hutten</a>, <a href="/search/astro-ph?searchtype=author&query=Hanna%2C+D">D. Hanna</a>, <a href="/search/astro-ph?searchtype=author&query=Holder%2C+J">J. Holder</a>, <a href="/search/astro-ph?searchtype=author&query=Johnson%2C+C+A">C. A. Johnson</a> , et al. (42 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1701.06740v1-abstract-short" style="display: inline;"> High-energy gamma-ray emission from supernova remnants (SNRs) has provided a unique perspective for studies of Galactic cosmic-ray acceleration. Tycho's SNR is a particularly good target because it is a young, type Ia SNR that is well-studied over a wide range of energies and located in a relatively clean environment. Since the detection of gamma-ray emission from Tycho's SNR by VERITAS and Fermi-… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1701.06740v1-abstract-full').style.display = 'inline'; document.getElementById('1701.06740v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1701.06740v1-abstract-full" style="display: none;"> High-energy gamma-ray emission from supernova remnants (SNRs) has provided a unique perspective for studies of Galactic cosmic-ray acceleration. Tycho's SNR is a particularly good target because it is a young, type Ia SNR that is well-studied over a wide range of energies and located in a relatively clean environment. Since the detection of gamma-ray emission from Tycho's SNR by VERITAS and Fermi-LAT, there have been several theoretical models proposed to explain its broadband emission and high-energy morphology. We report on an update to the gamma-ray measurements of Tycho's SNR with 147 hours of VERITAS and 84 months of Fermi-LAT observations, which represents about a factor of two increase in exposure over previously published data. About half of the VERITAS data benefited from a camera upgrade, which has made it possible to extend the TeV measurements toward lower energies. The TeV spectral index measured by VERITAS is consistent with previous results, but the expanded energy range softens a straight power-law fit. At energies higher than 400 GeV, the power-law index is $2.92 \pm 0.42_{\mathrm{stat}} \pm 0.20_{\mathrm{sys}}$. It is also softer than the spectral index in the GeV energy range, $2.14 \pm 0.09_{\mathrm{stat}} \pm 0.02_{\mathrm{sys}}$, measured by this study using Fermi--LAT data. The centroid position of the gamma-ray emission is coincident with the center of the remnant, as well as with the centroid measurement of Fermi--LAT above 1 GeV. The results are consistent with an SNR shell origin of the emission, as many models assume. The updated spectrum points to a lower maximum particle energy than has been suggested previously. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1701.06740v1-abstract-full').style.display = 'none'; document.getElementById('1701.06740v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 January, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in The Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1701.01067">arXiv:1701.01067</a> <span> [<a href="https://arxiv.org/pdf/1701.01067">pdf</a>, <a href="https://arxiv.org/ps/1701.01067">ps</a>, <a href="https://arxiv.org/format/1701.01067">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/836/2/205">10.3847/1538-4357/836/2/205 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A luminous and isolated gamma-ray flare from the blazar B2 1215+30 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=VERITAS+Collaboration"> VERITAS Collaboration</a>, <a href="/search/astro-ph?searchtype=author&query=Abeysekara%2C+A+U">A. U. Abeysekara</a>, <a href="/search/astro-ph?searchtype=author&query=Archambault%2C+S">S. Archambault</a>, <a href="/search/astro-ph?searchtype=author&query=Archer%2C+A">A. Archer</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Bird%2C+R">R. Bird</a>, <a href="/search/astro-ph?searchtype=author&query=Buchovecky%2C+M">M. Buchovecky</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Bugaev%2C+V">V. Bugaev</a>, <a href="/search/astro-ph?searchtype=author&query=Byrum%2C+K">K. Byrum</a>, <a href="/search/astro-ph?searchtype=author&query=Cerruti%2C+M">M. Cerruti</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+X">X. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Ciupik%2C+L">L. Ciupik</a>, <a href="/search/astro-ph?searchtype=author&query=Cui%2C+W">W. Cui</a>, <a href="/search/astro-ph?searchtype=author&query=Dickinson%2C+H+J">H. J. Dickinson</a>, <a href="/search/astro-ph?searchtype=author&query=Eisch%2C+J+D">J. D. Eisch</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">A. Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+J+P">J. P. Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Fleischhack%2C+H">H. Fleischhack</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">A. Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Gillanders%2C+G+H">G. H. Gillanders</a>, <a href="/search/astro-ph?searchtype=author&query=Griffin%2C+S">S. Griffin</a> , et al. (62 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1701.01067v1-abstract-short" style="display: inline;"> B2 1215+30 is a BL Lac-type blazar that was first detected at TeV energies by the MAGIC atmospheric Cherenkov telescopes, and subsequently confirmed by the VERITAS observatory with data collected between 2009 and 2012. In 2014 February 08, VERITAS detected a large-amplitude flare from B2 1215+30 during routine monitoring observations of the blazar 1ES 1218+304, located in the same field of view. T… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1701.01067v1-abstract-full').style.display = 'inline'; document.getElementById('1701.01067v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1701.01067v1-abstract-full" style="display: none;"> B2 1215+30 is a BL Lac-type blazar that was first detected at TeV energies by the MAGIC atmospheric Cherenkov telescopes, and subsequently confirmed by the VERITAS observatory with data collected between 2009 and 2012. In 2014 February 08, VERITAS detected a large-amplitude flare from B2 1215+30 during routine monitoring observations of the blazar 1ES 1218+304, located in the same field of view. The TeV flux reached 2.4 times the Crab Nebula flux with a variability timescale of < 3.6 h. Multiwavelength observations with Fermi-LAT, Swift, and the Tuorla observatory revealed a correlated high GeV flux state and no significant optical counterpart to the flare, with a spectral energy distribution where the gamma-ray luminosity exceeds the synchrotron luminosity. When interpreted in the framework of a one-zone leptonic model, the observed emission implies a high degree of beaming, with Doppler factor > 10, and an electron population with spectral index < 2.3. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1701.01067v1-abstract-full').style.display = 'none'; document.getElementById('1701.01067v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 January, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 pages, 3 figures, accepted for publication in The Astrophysical Journal</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJ, 836, 205 (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1610.01814">arXiv:1610.01814</a> <span> [<a href="https://arxiv.org/pdf/1610.01814">pdf</a>, <a href="https://arxiv.org/ps/1610.01814">ps</a>, <a href="https://arxiv.org/format/1610.01814">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1748-0221/11/11/P11009">10.1088/1748-0221/11/11/P11009 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Very High-Energy Gamma-Ray Follow-Up Program Using Neutrino Triggers from IceCube </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=IceCube+Collaboration"> IceCube Collaboration</a>, <a href="/search/astro-ph?searchtype=author&query=Aartsen%2C+M+G">M. G. Aartsen</a>, <a href="/search/astro-ph?searchtype=author&query=Abraham%2C+K">K. Abraham</a>, <a href="/search/astro-ph?searchtype=author&query=Ackermann%2C+M">M. Ackermann</a>, <a href="/search/astro-ph?searchtype=author&query=Adams%2C+J">J. Adams</a>, <a href="/search/astro-ph?searchtype=author&query=Aguilar%2C+J+A">J. A. Aguilar</a>, <a href="/search/astro-ph?searchtype=author&query=Ahlers%2C+M">M. Ahlers</a>, <a href="/search/astro-ph?searchtype=author&query=Ahrens%2C+M">M. Ahrens</a>, <a href="/search/astro-ph?searchtype=author&query=Altmann%2C+D">D. Altmann</a>, <a href="/search/astro-ph?searchtype=author&query=Andeen%2C+K">K. Andeen</a>, <a href="/search/astro-ph?searchtype=author&query=Anderson%2C+T">T. Anderson</a>, <a href="/search/astro-ph?searchtype=author&query=Ansseau%2C+I">I. Ansseau</a>, <a href="/search/astro-ph?searchtype=author&query=Anton%2C+G">G. Anton</a>, <a href="/search/astro-ph?searchtype=author&query=Archinger%2C+M">M. Archinger</a>, <a href="/search/astro-ph?searchtype=author&query=Arguelles%2C+C">C. Arguelles</a>, <a href="/search/astro-ph?searchtype=author&query=Auffenberg%2C+J">J. Auffenberg</a>, <a href="/search/astro-ph?searchtype=author&query=Axani%2C+S">S. Axani</a>, <a href="/search/astro-ph?searchtype=author&query=Bai%2C+X">X. Bai</a>, <a href="/search/astro-ph?searchtype=author&query=Barwick%2C+S+W">S. W. Barwick</a>, <a href="/search/astro-ph?searchtype=author&query=Baum%2C+V">V. Baum</a>, <a href="/search/astro-ph?searchtype=author&query=Bay%2C+R">R. Bay</a>, <a href="/search/astro-ph?searchtype=author&query=Beatty%2C+J+J">J. J. Beatty</a>, <a href="/search/astro-ph?searchtype=author&query=Becker-Tjus%2C+J">J. Becker-Tjus</a>, <a href="/search/astro-ph?searchtype=author&query=Becker%2C+K+-">K. -H. Becker</a>, <a href="/search/astro-ph?searchtype=author&query=BenZvi%2C+S">S. BenZvi</a> , et al. (519 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1610.01814v3-abstract-short" style="display: inline;"> We describe and report the status of a neutrino-triggered program in IceCube that generates real-time alerts for gamma-ray follow-up observations by atmospheric-Cherenkov telescopes (MAGIC and VERITAS). While IceCube is capable of monitoring the whole sky continuously, high-energy gamma-ray telescopes have restricted fields of view and in general are unlikely to be observing a potential neutrino-f… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1610.01814v3-abstract-full').style.display = 'inline'; document.getElementById('1610.01814v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1610.01814v3-abstract-full" style="display: none;"> We describe and report the status of a neutrino-triggered program in IceCube that generates real-time alerts for gamma-ray follow-up observations by atmospheric-Cherenkov telescopes (MAGIC and VERITAS). While IceCube is capable of monitoring the whole sky continuously, high-energy gamma-ray telescopes have restricted fields of view and in general are unlikely to be observing a potential neutrino-flaring source at the time such neutrinos are recorded. The use of neutrino-triggered alerts thus aims at increasing the availability of simultaneous multi-messenger data during potential neutrino flaring activity, which can increase the discovery potential and constrain the phenomenological interpretation of the high-energy emission of selected source classes (e.g. blazars). The requirements of a fast and stable online analysis of potential neutrino signals and its operation are presented, along with first results of the program operating between 14 March 2012 and 31 December 2015. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1610.01814v3-abstract-full').style.display = 'none'; document.getElementById('1610.01814v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 November, 2016; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 October, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">accepted for publication in JINST</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> 2016 JINST 11 P11009 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1608.06464">arXiv:1608.06464</a> <span> [<a href="https://arxiv.org/pdf/1608.06464">pdf</a>, <a href="https://arxiv.org/format/1608.06464">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/0004-637X/831/1/113">10.3847/0004-637X/831/1/113 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Very-high-energy observations of the binaries V 404 Cyg and 4U 0115+634 during giant X-ray outbursts </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Archer%2C+A">A. Archer</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Bird%2C+R">R. Bird</a>, <a href="/search/astro-ph?searchtype=author&query=Bourbeau%2C+E">E. Bourbeau</a>, <a href="/search/astro-ph?searchtype=author&query=Buchovecky%2C+M">M. Buchovecky</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Bugaev%2C+V">V. Bugaev</a>, <a href="/search/astro-ph?searchtype=author&query=Byrum%2C+K">K. Byrum</a>, <a href="/search/astro-ph?searchtype=author&query=Cerruti%2C+M">M. Cerruti</a>, <a href="/search/astro-ph?searchtype=author&query=Connolly%2C+M+P">M. P. Connolly</a>, <a href="/search/astro-ph?searchtype=author&query=Cui%2C+W">W. Cui</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">A. Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Fernandez-Alonso%2C+M">M. Fernandez-Alonso</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+J+P">J. P. Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Fleischhack%2C+H">H. Fleischhack</a>, <a href="/search/astro-ph?searchtype=author&query=Flinders%2C+A">A. Flinders</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">A. Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Griffin%2C+S">S. Griffin</a>, <a href="/search/astro-ph?searchtype=author&query=Grube%2C+J">J. Grube</a>, <a href="/search/astro-ph?searchtype=author&query=H%C3%BCtten%2C+M">M. H眉tten</a>, <a href="/search/astro-ph?searchtype=author&query=Hanna%2C+D">D. Hanna</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">O. Hervet</a> , et al. (40 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1608.06464v1-abstract-short" style="display: inline;"> Transient X-ray binaries produce major outbursts in which the X-ray flux can increase over the quiescent level by factors as large as $10^7$. The low-mass X-ray binary V 404 Cyg and the high-mass system 4U 0115+634 underwent such major outbursts in June and October 2015, respectively. We present here observations at energies above hundreds of GeV with the VERITAS observatory taken during some of t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1608.06464v1-abstract-full').style.display = 'inline'; document.getElementById('1608.06464v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1608.06464v1-abstract-full" style="display: none;"> Transient X-ray binaries produce major outbursts in which the X-ray flux can increase over the quiescent level by factors as large as $10^7$. The low-mass X-ray binary V 404 Cyg and the high-mass system 4U 0115+634 underwent such major outbursts in June and October 2015, respectively. We present here observations at energies above hundreds of GeV with the VERITAS observatory taken during some of the brightest X-ray activity ever observed from these systems. No gamma-ray emission has been detected by VERITAS in 2.5 hours of observations of the microquasar V 404 Cyg from 2015, June 20-21. The upper flux limits derived from these observations on the gamma-ray flux above 200 GeV of F $< 4.4\times 10^{-12}$ cm$^{-2}$ s$^{-1}$ correspond to a tiny fraction (about $10^{-6}$) of the Eddington luminosity of the system, in stark contrast to that seen in the X-ray band. No gamma rays have been detected during observations of 4U 0115+634 in the period of major X-ray activity in October 2015. The flux upper limit derived from our observations is F $< 2.1\times 10^{-12}$ cm$^{-2}$ s$^{-1}$ for gamma rays above 300 GeV, setting an upper limit on the ratio of gamma-ray to X-ray luminosity of less than 4%. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1608.06464v1-abstract-full').style.display = 'none'; document.getElementById('1608.06464v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 August, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in the Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1608.02769">arXiv:1608.02769</a> <span> [<a href="https://arxiv.org/pdf/1608.02769">pdf</a>, <a href="https://arxiv.org/ps/1608.02769">ps</a>, <a href="https://arxiv.org/format/1608.02769">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stw1319">10.1093/mnras/stw1319 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Discovery of Very High Energy Gamma Rays from 1ES 1440+122 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=VERITAS+Collaboration"> VERITAS Collaboration</a>, <a href="/search/astro-ph?searchtype=author&query=Archambault%2C+S">S. Archambault</a>, <a href="/search/astro-ph?searchtype=author&query=Archer%2C+A">A. Archer</a>, <a href="/search/astro-ph?searchtype=author&query=Barnacka%2C+A">A. Barnacka</a>, <a href="/search/astro-ph?searchtype=author&query=Behera%2C+B">B. Behera</a>, <a href="/search/astro-ph?searchtype=author&query=Beilicke%2C+M">M. Beilicke</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Berger%2C+K">K. Berger</a>, <a href="/search/astro-ph?searchtype=author&query=Bird%2C+R">R. Bird</a>, <a href="/search/astro-ph?searchtype=author&query=Boettcher%2C+M">M. Boettcher</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Bugaev%2C+V">V. Bugaev</a>, <a href="/search/astro-ph?searchtype=author&query=Cardenzana%2C+J+V">J. V Cardenzana</a>, <a href="/search/astro-ph?searchtype=author&query=Cerruti%2C+M">M. Cerruti</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+X">X. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Christiansen%2C+J+L">J. L. Christiansen</a>, <a href="/search/astro-ph?searchtype=author&query=Ciupik%2C+L">L. Ciupik</a>, <a href="/search/astro-ph?searchtype=author&query=Collins-Hughes%2C+E">E. Collins-Hughes</a>, <a href="/search/astro-ph?searchtype=author&query=Connolly%2C+M+P">M. P. Connolly</a>, <a href="/search/astro-ph?searchtype=author&query=Cui%2C+W">W. Cui</a>, <a href="/search/astro-ph?searchtype=author&query=Dickinson%2C+H+J">H. J. Dickinson</a>, <a href="/search/astro-ph?searchtype=author&query=Dumm%2C+J">J. Dumm</a>, <a href="/search/astro-ph?searchtype=author&query=Eisch%2C+J+D">J. D. Eisch</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">A. Falcone</a> , et al. (65 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1608.02769v1-abstract-short" style="display: inline;"> The BL Lacertae object 1ES 1440+122 was observed in the energy range from 85 GeV to 30 TeV by the VERITAS array of imaging atmospheric Cherenkov telescopes. The observations, taken between 2008 May and 2010 June and totalling 53 hours, resulted in the discovery of $纬$-ray emission from the blazar, which has a redshift $z$=0.163. 1ES 1440+122 is detected at a statistical significance of 5.5 standar… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1608.02769v1-abstract-full').style.display = 'inline'; document.getElementById('1608.02769v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1608.02769v1-abstract-full" style="display: none;"> The BL Lacertae object 1ES 1440+122 was observed in the energy range from 85 GeV to 30 TeV by the VERITAS array of imaging atmospheric Cherenkov telescopes. The observations, taken between 2008 May and 2010 June and totalling 53 hours, resulted in the discovery of $纬$-ray emission from the blazar, which has a redshift $z$=0.163. 1ES 1440+122 is detected at a statistical significance of 5.5 standard deviations above the background with an integral flux of (2.8$\pm0.7_{\mathrm{stat}}\pm0.8_{\mathrm{sys}}$) $\times$ 10$^{-12}$ cm$^{-2}$ s$^{-1}$ (1.2\% of the Crab Nebula's flux) above 200 GeV. The measured spectrum is described well by a power law from 0.2 TeV to 1.3 TeV with a photon index of 3.1 $\pm$ 0.4$_{\mathrm{stat}}$ $\pm$ 0.2$_{\mathrm{sys}}$. Quasi-simultaneous multi-wavelength data from the Fermi Large Area Telescope (0.3--300 GeV) and the Swift X-ray Telescope (0.2--10 keV) are additionally used to model the properties of the emission region. A synchrotron self-Compton model produces a good representation of the multi-wavelength data. Adding an external-Compton or a hadronic component also adequately describes the data. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1608.02769v1-abstract-full').style.display = 'none'; document.getElementById('1608.02769v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 August, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 pages, 4 figures. Accepted for publication in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1603.07286">arXiv:1603.07286</a> <span> [<a href="https://arxiv.org/pdf/1603.07286">pdf</a>, <a href="https://arxiv.org/ps/1603.07286">ps</a>, <a href="https://arxiv.org/format/1603.07286">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stw664">10.1093/mnras/stw664 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> VERITAS and Multiwavelength Observations of the BL Lacertae Object 1ES 1741+196 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=VERITAS+Collaboration"> VERITAS Collaboration</a>, <a href="/search/astro-ph?searchtype=author&query=Abeysekara%2C+A+U">A. U. Abeysekara</a>, <a href="/search/astro-ph?searchtype=author&query=Archambault%2C+S">S. Archambault</a>, <a href="/search/astro-ph?searchtype=author&query=Archer%2C+A">A. Archer</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Bird%2C+R">R. Bird</a>, <a href="/search/astro-ph?searchtype=author&query=Biteau%2C+J">J. Biteau</a>, <a href="/search/astro-ph?searchtype=author&query=Buchovecky%2C+M">M. Buchovecky</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Bugaev%2C+V">V. Bugaev</a>, <a href="/search/astro-ph?searchtype=author&query=Byrum%2C+K">K. Byrum</a>, <a href="/search/astro-ph?searchtype=author&query=Cardenzana%2C+J+V">J. V Cardenzana</a>, <a href="/search/astro-ph?searchtype=author&query=Cerruti%2C+M">M. Cerruti</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+X">X. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Christiansen%2C+J+L">J. L. Christiansen</a>, <a href="/search/astro-ph?searchtype=author&query=Ciupik%2C+L">L. Ciupik</a>, <a href="/search/astro-ph?searchtype=author&query=Connolly%2C+M+P">M. P. Connolly</a>, <a href="/search/astro-ph?searchtype=author&query=Cui%2C+W">W. Cui</a>, <a href="/search/astro-ph?searchtype=author&query=Dickinson%2C+H+J">H. J. Dickinson</a>, <a href="/search/astro-ph?searchtype=author&query=Dumm%2C+J">J. Dumm</a>, <a href="/search/astro-ph?searchtype=author&query=Eisch%2C+J+D">J. D. Eisch</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">A. Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+J+P">J. P. Finley</a> , et al. (63 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1603.07286v1-abstract-short" style="display: inline;"> We present results from multiwavelength observations of the BL Lacertae object 1ES 1741+196, including results in the very-high-energy $纬$-ray regime using the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The VERITAS time-averaged spectrum, measured above 180 GeV, is well-modelled by a power law with a spectral index of $2.7\pm0.7_{\mathrm{stat}}\pm0.2_{\mathrm{syst}}$. The i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1603.07286v1-abstract-full').style.display = 'inline'; document.getElementById('1603.07286v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1603.07286v1-abstract-full" style="display: none;"> We present results from multiwavelength observations of the BL Lacertae object 1ES 1741+196, including results in the very-high-energy $纬$-ray regime using the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The VERITAS time-averaged spectrum, measured above 180 GeV, is well-modelled by a power law with a spectral index of $2.7\pm0.7_{\mathrm{stat}}\pm0.2_{\mathrm{syst}}$. The integral flux above 180 GeV is $(3.9\pm0.8_{\mathrm{stat}}\pm1.0_{\mathrm{syst}})\times 10^{-8}$ m$^{-2}$ s$^{-1}$, corresponding to 1.6% of the Crab Nebula flux on average. The multiwavelength spectral energy distribution of the source suggests that 1ES 1741+196 is an extreme-high-frequency-peaked BL Lacertae object. The observations analysed in this paper extend over a period of six years, during which time no strong flares were observed in any band. This analysis is therefore one of the few characterizations of a blazar in a non-flaring state. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1603.07286v1-abstract-full').style.display = 'none'; document.getElementById('1603.07286v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 March, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 pages, 5 figures. Accepted for publication in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1603.02410">arXiv:1603.02410</a> <span> [<a href="https://arxiv.org/pdf/1603.02410">pdf</a>, <a href="https://arxiv.org/format/1603.02410">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/0004-6256/151/6/142">10.3847/0004-6256/151/6/142 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Upper limits from five years of blazar observations with the VERITAS Cherenkov telescopes </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Archambault%2C+S">S. Archambault</a>, <a href="/search/astro-ph?searchtype=author&query=Archer%2C+A">A. Archer</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Bird%2C+R">R. Bird</a>, <a href="/search/astro-ph?searchtype=author&query=Biteau%2C+J">J. Biteau</a>, <a href="/search/astro-ph?searchtype=author&query=Buchovecky%2C+M">M. Buchovecky</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Bugaev%2C+V">V. Bugaev</a>, <a href="/search/astro-ph?searchtype=author&query=Byrum%2C+K">K. Byrum</a>, <a href="/search/astro-ph?searchtype=author&query=Cerruti%2C+M">M. Cerruti</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+X">X. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Ciupik%2C+L">L. Ciupik</a>, <a href="/search/astro-ph?searchtype=author&query=Connolly%2C+M+P">M. P. Connolly</a>, <a href="/search/astro-ph?searchtype=author&query=Cui%2C+W">W. Cui</a>, <a href="/search/astro-ph?searchtype=author&query=Eisch%2C+J+D">J. D. Eisch</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">A. Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+J+P">J. P. Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Fleischhack%2C+H">H. Fleischhack</a>, <a href="/search/astro-ph?searchtype=author&query=Fortin%2C+P">P. Fortin</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">A. Furniss</a>, <a href="/search/astro-ph?searchtype=author&query=Gillanders%2C+G+H">G. H. Gillanders</a>, <a href="/search/astro-ph?searchtype=author&query=Griffin%2C+S">S. Griffin</a> , et al. (56 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1603.02410v1-abstract-short" style="display: inline;"> Between the beginning of its full-scale scientific operations in 2007 and 2012, the VERITAS Cherenkov telescope array observed more than 130 blazars; of these, 26 were detected as very-high-energy (VHE; E>100 GeV) 纬-ray sources. In this work, we present the analysis results of a sample of 114 undetected objects. The observations constitute a total live-time of ~570 hours. The sample includes sever… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1603.02410v1-abstract-full').style.display = 'inline'; document.getElementById('1603.02410v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1603.02410v1-abstract-full" style="display: none;"> Between the beginning of its full-scale scientific operations in 2007 and 2012, the VERITAS Cherenkov telescope array observed more than 130 blazars; of these, 26 were detected as very-high-energy (VHE; E>100 GeV) 纬-ray sources. In this work, we present the analysis results of a sample of 114 undetected objects. The observations constitute a total live-time of ~570 hours. The sample includes several unidentified Fermi-Large Area Telescope (LAT) sources (located at high Galactic latitude) as well as all the sources from the second Fermi-LAT catalog which are contained within the field of view of the VERITAS observations. We have also performed optical spectroscopy measurements in order to estimate the redshift of some of these blazars that do not have a spectroscopic distance estimate. We present new optical spectra from the Kast instrument on the Shane telescope at the Lick observatory for 18 blazars included in this work, which allowed for the successful measurement or constraint on the redshift of four of them. For each of the blazars included in our sample we provide the flux upper limit in the VERITAS energy band. We also study the properties of the significance distributions and we present the result of a stacked analysis of the data-set, which shows a 4 蟽 excess. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1603.02410v1-abstract-full').style.display = 'none'; document.getElementById('1603.02410v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 March, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">22 pages; accepted for publication in The Astronomical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1602.00987">arXiv:1602.00987</a> <span> [<a href="https://arxiv.org/pdf/1602.00987">pdf</a>, <a href="https://arxiv.org/format/1602.00987">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/2041-8205/818/2/L33">10.3847/2041-8205/818/2/L33 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A Search for Brief Optical Flashes Associated with the SETI Target KIC 8462852 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Abeysekara%2C+A+U">A. U. Abeysekara</a>, <a href="/search/astro-ph?searchtype=author&query=Archambault%2C+S">S. Archambault</a>, <a href="/search/astro-ph?searchtype=author&query=Archer%2C+A">A. Archer</a>, <a href="/search/astro-ph?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/astro-ph?searchtype=author&query=Bird%2C+R">R. Bird</a>, <a href="/search/astro-ph?searchtype=author&query=Buchovecky%2C+M">M. Buchovecky</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Byrum%2C+K">K. Byrum</a>, <a href="/search/astro-ph?searchtype=author&query=Cardenzana%2C+J+V">J. V Cardenzana</a>, <a href="/search/astro-ph?searchtype=author&query=Cerruti%2C+M">M. Cerruti</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+X">X. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Christiansen%2C+J+L">J. L. Christiansen</a>, <a href="/search/astro-ph?searchtype=author&query=Ciupik%2C+L">L. Ciupik</a>, <a href="/search/astro-ph?searchtype=author&query=Cui%2C+W">W. Cui</a>, <a href="/search/astro-ph?searchtype=author&query=Dickinson%2C+H+J">H. J. Dickinson</a>, <a href="/search/astro-ph?searchtype=author&query=Eisch%2C+J+D">J. D. Eisch</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A">A. Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Fegan%2C+D+J">D. J. Fegan</a>, <a href="/search/astro-ph?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/astro-ph?searchtype=author&query=Finley%2C+J+P">J. P. Finley</a>, <a href="/search/astro-ph?searchtype=author&query=Fleischhack%2C+H">H. Fleischhack</a>, <a href="/search/astro-ph?searchtype=author&query=Fortin%2C+P">P. Fortin</a>, <a href="/search/astro-ph?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/astro-ph?searchtype=author&query=Furniss%2C+A">A. Furniss</a> , et al. (56 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1602.00987v2-abstract-short" style="display: inline;"> The F-type star KIC 8462852 has recently been identified as an exceptional target for SETI (search for extraterrestrial intelligence) observations. We describe an analysis methodology for optical SETI, which we have used to analyse nine hours of serendipitous archival observations of KIC 8462852 made with the VERITAS gamma-ray observatory between 2009 and 2015. No evidence of pulsed optical beacon… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1602.00987v2-abstract-full').style.display = 'inline'; document.getElementById('1602.00987v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1602.00987v2-abstract-full" style="display: none;"> The F-type star KIC 8462852 has recently been identified as an exceptional target for SETI (search for extraterrestrial intelligence) observations. We describe an analysis methodology for optical SETI, which we have used to analyse nine hours of serendipitous archival observations of KIC 8462852 made with the VERITAS gamma-ray observatory between 2009 and 2015. No evidence of pulsed optical beacons, above a pulse intensity at the Earth of approximately 1 photon per m^2, is found. We also discuss the potential use of imaging atmospheric Cherenkov telescope arrays in searching for extremely short duration optical transients in general. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1602.00987v2-abstract-full').style.display = 'none'; document.getElementById('1602.00987v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 February, 2016; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 February, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in ApJ Letters. Fixed a minor error in the title</span> </p> </li> </ol> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Errando%2C+M&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Errando%2C+M&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Errando%2C+M&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> <li> <a href="/search/?searchtype=author&query=Errando%2C+M&start=100" class="pagination-link " aria-label="Page 3" aria-current="page">3 </a> </li> </ul> </nav> <div class="is-hidden-tablet">  <span class="help" style="display: inline-block;"><a href="https://github.com/arXiv/arxiv-search/releases">Search v0.5.6 released 2020-02-24</a>  </span> 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