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</li> <li><span class="pagination-ellipsis">…</span></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/2411.08189">arXiv:2411.08189</a> <span> [<a href="https://arxiv.org/pdf/2411.08189">pdf</a>, <a href="https://arxiv.org/format/2411.08189">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"> High-Statistics Measurement of the Cosmic-Ray Electron Spectrum with H.E.S.S </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=Benkhali%2C+F+A">F. Ait Benkhali</a>, <a href="/search/?searchtype=author&query=Aschersleben%2C+J">J. Aschersleben</a>, <a href="/search/?searchtype=author&query=Ashkar%2C+H">H. Ashkar</a>, <a href="/search/?searchtype=author&query=Backes%2C+M">M. Backes</a>, <a href="/search/?searchtype=author&query=Martins%2C+V+B">V. Barbosa Martins</a>, <a href="/search/?searchtype=author&query=Batzofin%2C+R">R. Batzofin</a>, <a href="/search/?searchtype=author&query=Becherini%2C+Y">Y. Becherini</a>, <a href="/search/?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/?searchtype=author&query=Bernl%C3%B6hr%2C+K">K. Bernl枚hr</a>, <a href="/search/?searchtype=author&query=Bi%2C+B">B. Bi</a>, <a href="/search/?searchtype=author&query=B%C3%B6ttcher%2C+M">M. B枚ttcher</a>, <a href="/search/?searchtype=author&query=Boisson%2C+C">C. Boisson</a>, <a href="/search/?searchtype=author&query=Bolmont%2C+J">J. Bolmont</a>, <a href="/search/?searchtype=author&query=de+Lavergne%2C+M+d+B">M. de Bony de Lavergne</a>, <a href="/search/?searchtype=author&query=Borowska%2C+J">J. Borowska</a>, <a href="/search/?searchtype=author&query=Bouyahiaoui%2C+M">M. Bouyahiaoui</a>, <a href="/search/?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/?searchtype=author&query=Brown%2C+A">A. Brown</a>, <a href="/search/?searchtype=author&query=Brun%2C+F">F. Brun</a>, <a href="/search/?searchtype=author&query=Bruno%2C+B">B. Bruno</a>, <a href="/search/?searchtype=author&query=Bulik%2C+T">T. Bulik</a>, <a href="/search/?searchtype=author&query=Burger-Scheidlin%2C+C">C. Burger-Scheidlin</a>, <a href="/search/?searchtype=author&query=Bylund%2C+T">T. Bylund</a>, <a href="/search/?searchtype=author&query=Casanova%2C+S">S. Casanova</a> , et al. (123 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="2411.08189v1-abstract-short" style="display: inline;"> Owing to their rapid cooling rate and hence loss-limited propagation distance, cosmic-ray electrons and positrons (CRe) at very high energies probe local cosmic-ray accelerators and provide constraints on exotic production mechanisms such as annihilation of dark matter particles. We present a high-statistics measurement of the spectrum of CRe candidate events from 0.3 to 40 TeV with the High Energ… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.08189v1-abstract-full').style.display = 'inline'; document.getElementById('2411.08189v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.08189v1-abstract-full" style="display: none;"> Owing to their rapid cooling rate and hence loss-limited propagation distance, cosmic-ray electrons and positrons (CRe) at very high energies probe local cosmic-ray accelerators and provide constraints on exotic production mechanisms such as annihilation of dark matter particles. We present a high-statistics measurement of the spectrum of CRe candidate events from 0.3 to 40 TeV with the High Energy Stereoscopic System (H.E.S.S.), covering two orders of magnitude in energy and reaching a proton rejection power of better than $10^{4}$. The measured spectrum is well described by a broken power law, with a break around 1 TeV, where the spectral index increases from $螕_1 = 3.25$ $\pm$ 0.02 (stat) $\pm$ 0.2 (sys) to $螕_2 = 4.49$ $\pm$ 0.04 (stat) $\pm$ 0.2 (sys). Apart from the break, the spectrum is featureless. The absence of distinct signatures at multi-TeV energies imposes constraints on the presence of nearby CRe accelerators and the local CRe propagation mechanisms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.08189v1-abstract-full').style.display = 'none'; document.getElementById('2411.08189v1-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, 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">main paper: 8 pages, 4 figures, supplemental material: 12 pages, 14 figures, accepted for publication in Physical Review Letters https://journals.aps.org/prl/</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.01215">arXiv:2411.01215</a> <span> [<a href="https://arxiv.org/pdf/2411.01215">pdf</a>, <a href="https://arxiv.org/format/2411.01215">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"> Detection of two TeV gamma-ray outbursts from NGC 1275 by LHAASO </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=Axikegu"> Axikegu</a>, <a href="/search/?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+Z">S. Z. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+T+L">T. L. Chen</a> , et al. (254 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="2411.01215v2-abstract-short" style="display: inline;"> The Water Cherenkov Detector Array (WCDA) is one of the components of Large High Altitude Air Shower Observatory (LHAASO) and can monitor any sources over two-thirds of the sky for up to 7 hours per day with >98\% duty cycle. In this work, we report the detection of two outbursts of the Fanaroff-Riley I radio galaxy NGC 1275 that were detected by LHAASO-WCDA between November 2022 and January 2023… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.01215v2-abstract-full').style.display = 'inline'; document.getElementById('2411.01215v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.01215v2-abstract-full" style="display: none;"> The Water Cherenkov Detector Array (WCDA) is one of the components of Large High Altitude Air Shower Observatory (LHAASO) and can monitor any sources over two-thirds of the sky for up to 7 hours per day with >98\% duty cycle. In this work, we report the detection of two outbursts of the Fanaroff-Riley I radio galaxy NGC 1275 that were detected by LHAASO-WCDA between November 2022 and January 2023 with statistical significance of 5.2~$蟽$ and 8.3~$蟽$. The observed spectral energy distribution in the range from 500 GeV to 3 TeV is fitted by a power-law with a best-fit spectral index of $伪=-3.37\pm0.52$ and $-3.35\pm0.29$, respectively. The outburst flux above 0.5~TeV was ($4.55\pm 4.21)\times~10^{-11}~\rm cm^{-2}~s^{-1}$ and ($3.45\pm 1.78)\times~10^{-11}~\rm cm^{-2}~s^{-1}$, corresponding to 60\%, 45\% of Crab Nebula flux. Variation analysis reveals the variability time-scale of days at the TeV energy band. A simple test by one-zone synchrotron self-Compton model reproduces the data in the gamma-ray band well. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.01215v2-abstract-full').style.display = 'none'; document.getElementById('2411.01215v2-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> 5 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 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">11 pages, 8 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/2410.22199">arXiv:2410.22199</a> <span> [<a href="https://arxiv.org/pdf/2410.22199">pdf</a>, <a href="https://arxiv.org/format/2410.22199">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"> Confinement of relativistic particles in the vicinity of accelerators: a key for understanding the anomalies in secondary cosmic rays </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Yang%2C+R">Rui-zhi Yang</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">Felix Aharonian</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="2410.22199v1-abstract-short" style="display: inline;"> Recent cosmic ray (CR) measurements have revealed unexpected anomalies in secondary CRs, namely deviations from the predictions of the so-called standard Galactic CR paradigm regarding the composition and energy spectra of the products of interactions of primary (accelerated) CRs with interstellar gas: (i) antiparticles (positrons and antiprotons), (ii) light elements of the (Li, Be, B) group, and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.22199v1-abstract-full').style.display = 'inline'; document.getElementById('2410.22199v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.22199v1-abstract-full" style="display: none;"> Recent cosmic ray (CR) measurements have revealed unexpected anomalies in secondary CRs, namely deviations from the predictions of the so-called standard Galactic CR paradigm regarding the composition and energy spectra of the products of interactions of primary (accelerated) CRs with interstellar gas: (i) antiparticles (positrons and antiprotons), (ii) light elements of the (Li, Be, B) group, and (iii) diffuse gamma rays. We argue that the new measurements can still be explained within the standard CR paradigm but with an additional assumption that CRs spend a significant part of their lifetime near their formation sites. The latter can be realized if CRs propagate more slowly in these localized regions than in the interstellar medium (ISM). Postulating that CRs accumulate on average energy-independent "grammage" of $0.7 \ \rm g/cm^2$ near the major contributors to galactic CRs, one can explain self-consistently the new measurements of the B/C ratio by DAMPE and the diffuse ultra-high-energy gamma-rays by LHAASO, involving a minimal number of model parameters: the energy-dependent "grammage" in the interstellar medium $\rm 位\approx 8 (E/10 \ GeV)^{-0.55}~\rm g/cm^{2}$ and the average CR acceleration (sourcee) spectrum, $\rm Q(E) \propto E^{-2.3}$. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.22199v1-abstract-full').style.display = 'none'; document.getElementById('2410.22199v1-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> 29 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.04425">arXiv:2410.04425</a> <span> [<a href="https://arxiv.org/pdf/2410.04425">pdf</a>, <a href="https://arxiv.org/format/2410.04425">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"> LHAASO detection of very-high-energy gamma-ray emission surrounding PSR J0248+6021 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=An%2C+Q">Q. An</a>, <a href="/search/?searchtype=author&query=Axikegu"> Axikegu</a>, <a href="/search/?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+Z">S. Z. Chen</a> , et al. (255 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="2410.04425v1-abstract-short" style="display: inline;"> We report the detection of an extended very-high-energy (VHE) gamma-ray source coincident with the locations of middle-aged (62.4~\rm kyr) pulsar PSR J0248+6021, by using the LHAASO-WCDA data of live 796 days and LHAASO-KM2A data of live 1216 days. A significant excess of \gray induced showers is observed both by WCDA in energy bands of 1-25~\rm TeV and KM2A in energy bands of $>$ 25~\rm TeV with… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.04425v1-abstract-full').style.display = 'inline'; document.getElementById('2410.04425v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.04425v1-abstract-full" style="display: none;"> We report the detection of an extended very-high-energy (VHE) gamma-ray source coincident with the locations of middle-aged (62.4~\rm kyr) pulsar PSR J0248+6021, by using the LHAASO-WCDA data of live 796 days and LHAASO-KM2A data of live 1216 days. A significant excess of \gray induced showers is observed both by WCDA in energy bands of 1-25~\rm TeV and KM2A in energy bands of $>$ 25~\rm TeV with 7.3 $蟽$ and 13.5 $蟽$, respectively. The best-fit position derived through WCDA data is R.A. = 42.06$^\circ \pm$ 0.12$^\circ$ and Dec. = 60.24$^\circ \pm $ 0.13$^\circ$ with an extension of 0.69$^\circ\pm$0.15$^\circ$ and that of the KM2A data is R.A.= 42.29$^\circ \pm $ 0.13$^\circ$ and Dec. = 60.38$^\circ \pm$ 0.07$^\circ$ with an extension of 0.37$^\circ\pm$0.07$^\circ$. No clear extended multiwavelength counterpart of this LHAASO source has been found from the radio band to the GeV band. The most plausible explanation of the VHE \gray emission is the inverse Compton process of highly relativistic electrons and positrons injected by the pulsar. These electrons/positrons are hypothesized to be either confined within the pulsar wind nebula or to have already escaped into the interstellar medium, forming a pulsar halo. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.04425v1-abstract-full').style.display = 'none'; document.getElementById('2410.04425v1-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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">12 pages, 10 figures, Accepted by Sci. China-Phys. Mech. Astron</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.06312">arXiv:2408.06312</a> <span> [<a href="https://arxiv.org/pdf/2408.06312">pdf</a>, <a href="https://arxiv.org/format/2408.06312">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</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/10.1038/s41550-024-02362-0">10.1038/s41550-024-02362-0 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A magnetised Galactic halo from inner Galaxy outflows </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Zhang%2C+H">He-Shou Zhang</a>, <a href="/search/?searchtype=author&query=Ponti%2C+G">Gabriele Ponti</a>, <a href="/search/?searchtype=author&query=Carretti%2C+E">Ettore Carretti</a>, <a href="/search/?searchtype=author&query=Liu%2C+R">Ruo-Yu Liu</a>, <a href="/search/?searchtype=author&query=Morris%2C+M+R">Mark R. Morris</a>, <a href="/search/?searchtype=author&query=Haverkorn%2C+M">Marijke Haverkorn</a>, <a href="/search/?searchtype=author&query=Locatelli%2C+N">Nicola Locatelli</a>, <a href="/search/?searchtype=author&query=Zheng%2C+X">Xueying Zheng</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">Felix Aharonian</a>, <a href="/search/?searchtype=author&query=Zhang%2C+H">Haiming Zhang</a>, <a href="/search/?searchtype=author&query=Zhang%2C+Y">Yi Zhang</a>, <a href="/search/?searchtype=author&query=Stel%2C+G">Giovanni Stel</a>, <a href="/search/?searchtype=author&query=Strong%2C+A">Andrew Strong</a>, <a href="/search/?searchtype=author&query=Yeung%2C+M">Micheal Yeung</a>, <a href="/search/?searchtype=author&query=Merloni%2C+A">Andrea Merloni</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="2408.06312v1-abstract-short" style="display: inline;"> Large-scale magnetic fields are observed off the midplanes of disk galaxies, indicating that they harbour magnetised halos. These halos are crucial to studies of galaxy evolution, galactic-scale outflows, and feedback from star formation activity. Identifying the magnetised halo of the Milky Way is challenging because of the potential contamination from foreground emission arising in local spiral… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.06312v1-abstract-full').style.display = 'inline'; document.getElementById('2408.06312v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.06312v1-abstract-full" style="display: none;"> Large-scale magnetic fields are observed off the midplanes of disk galaxies, indicating that they harbour magnetised halos. These halos are crucial to studies of galaxy evolution, galactic-scale outflows, and feedback from star formation activity. Identifying the magnetised halo of the Milky Way is challenging because of the potential contamination from foreground emission arising in local spiral arms. Additionally, it is unclear how our magnetic halo is influenced by recently revealed large-scale structures such as the X-ray emitting eROSITA Bubbles, which, according to previous simulations, might be transient structures powered by the Galactic Center or the Galaxy's star-forming ring. Here we report the identification of several kpc-scale magnetised structures based on their polarized radio emission and their gamma-ray counterparts, which can be interpreted as the radiation of relativistic electrons. These non-thermal structures extend far above and below the Galactic plane and are spatially coincident with the thermal X-ray emission from the eROSITA Bubbles. The morphological consistency of these structures suggests a common origin, which can be sustained by Galactic outflows driven by the active star-forming regions located at 3-5 kpc from the Galactic Centre. These results reveal how X-ray-emitting and magnetised halos of spiral galaxies can be related to intense star formation activities and suggest that the X-shaped coherent magnetic structures observed in their halos can stem from galaxy outflows. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.06312v1-abstract-full').style.display = 'none'; document.getElementById('2408.06312v1-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 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 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">Initially submitted on March 2nd, 2024</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Astronomy (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.16219">arXiv:2407.16219</a> <span> [<a href="https://arxiv.org/pdf/2407.16219">pdf</a>, <a href="https://arxiv.org/format/2407.16219">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/ad5e67">10.3847/2041-8213/ad5e67 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Very-high-energy $纬$-ray emission from young massive star clusters in the Large Magellanic Cloud </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=Benkhali%2C+F+A">F. Ait Benkhali</a>, <a href="/search/?searchtype=author&query=Aschersleben%2C+J">J. Aschersleben</a>, <a href="/search/?searchtype=author&query=Ashkar%2C+H">H. Ashkar</a>, <a href="/search/?searchtype=author&query=Backes%2C+M">M. Backes</a>, <a href="/search/?searchtype=author&query=Martins%2C+V+B">V. Barbosa Martins</a>, <a href="/search/?searchtype=author&query=Batzofin%2C+R">R. Batzofin</a>, <a href="/search/?searchtype=author&query=Becherini%2C+Y">Y. Becherini</a>, <a href="/search/?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/?searchtype=author&query=Bernl%C3%B6hr%2C+K">K. Bernl枚hr</a>, <a href="/search/?searchtype=author&query=B%C3%B6ttcher%2C+M">M. B枚ttcher</a>, <a href="/search/?searchtype=author&query=Bolmont%2C+J">J. Bolmont</a>, <a href="/search/?searchtype=author&query=de+Lavergne%2C+M+d+B">M. de Bony de Lavergne</a>, <a href="/search/?searchtype=author&query=Borowska%2C+J">J. Borowska</a>, <a href="/search/?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/?searchtype=author&query=Brown%2C+A">A. Brown</a>, <a href="/search/?searchtype=author&query=Brun%2C+F">F. Brun</a>, <a href="/search/?searchtype=author&query=Bruno%2C+B">B. Bruno</a>, <a href="/search/?searchtype=author&query=Burger-Scheidlin%2C+C">C. Burger-Scheidlin</a>, <a href="/search/?searchtype=author&query=Casanova%2C+S">S. Casanova</a>, <a href="/search/?searchtype=author&query=Celic%2C+J">J. Celic</a>, <a href="/search/?searchtype=author&query=Cerruti%2C+M">M. Cerruti</a>, <a href="/search/?searchtype=author&query=Chand%2C+T">T. Chand</a>, <a href="/search/?searchtype=author&query=Chandra%2C+S">S. Chandra</a>, <a href="/search/?searchtype=author&query=Chen%2C+A">A. Chen</a> , et al. (107 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="2407.16219v1-abstract-short" style="display: inline;"> The Tarantula Nebula in the Large Magellanic Cloud is known for its high star formation activity. At its center lies the young massive star cluster R136, providing a significant amount of the energy that makes the nebula shine so brightly at many wavelengths. Recently, young massive star clusters have been suggested to also efficiently produce high-energy cosmic rays, potentially beyond PeV energi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.16219v1-abstract-full').style.display = 'inline'; document.getElementById('2407.16219v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.16219v1-abstract-full" style="display: none;"> The Tarantula Nebula in the Large Magellanic Cloud is known for its high star formation activity. At its center lies the young massive star cluster R136, providing a significant amount of the energy that makes the nebula shine so brightly at many wavelengths. Recently, young massive star clusters have been suggested to also efficiently produce high-energy cosmic rays, potentially beyond PeV energies. Here, we report the detection of very-high-energy $纬$-ray emission from the direction of R136 with the High Energy Stereoscopic System, achieved through a multicomponent, likelihood-based modeling of the data. This supports the hypothesis that R136 is indeed a very powerful cosmic-ray accelerator. Moreover, from the same analysis, we provide an updated measurement of the $纬$-ray emission from 30 Dor C, the only superbubble detected at TeV energies presently. The $纬$-ray luminosity above $0.5\,\mathrm{TeV}$ of both sources is $(2-3)\times 10^{35}\,\mathrm{erg}\,\mathrm{s}^{-1}$. This exceeds by more than a factor of 2 the luminosity of HESS J1646$-$458, which is associated with the most massive young star cluster in the Milky Way, Westerlund 1. Furthermore, the $纬$-ray emission from each source is extended with a significance of $>3蟽$ and a Gaussian width of about $30\,\mathrm{pc}$. For 30 Dor C, a connection between the $纬$-ray emission and the nonthermal X-ray emission appears likely. Different interpretations of the $纬$-ray signal from R136 are discussed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.16219v1-abstract-full').style.display = 'none'; document.getElementById('2407.16219v1-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">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">10+11 pages, 4+6 figures. Corresponding authors: L. Mohrmann, N. Komin</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Astrophysical Journal Letters 970, L21 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.07509">arXiv:2407.07509</a> <span> [<a href="https://arxiv.org/pdf/2407.07509">pdf</a>, <a href="https://arxiv.org/format/2407.07509">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/s41550-023-02168-6">10.1038/s41550-023-02168-6 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The contribution of winds of star clusters to the Galactic cosmic-ray population </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Peron%2C+G">Giada Peron</a>, <a href="/search/?searchtype=author&query=Casanova%2C+S">Sabrina Casanova</a>, <a href="/search/?searchtype=author&query=Gabici%2C+S">Stefano Gabici</a>, <a href="/search/?searchtype=author&query=Baghmanyan%2C+V">Vardan Baghmanyan</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">Felix Aharonian</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="2407.07509v1-abstract-short" style="display: inline;"> Cosmic rays are energetic nuclei that permeate the entire Galactic disk. Their existence requires the presence of powerful particle accelerators. While Galactic supernova explosions may supply the required energy, there is growing evidence that they cannot explain all of the observed properties of cosmic rays, such as their maximum particle energy and isotopic composition. Among Galactic objects,… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.07509v1-abstract-full').style.display = 'inline'; document.getElementById('2407.07509v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.07509v1-abstract-full" style="display: none;"> Cosmic rays are energetic nuclei that permeate the entire Galactic disk. Their existence requires the presence of powerful particle accelerators. While Galactic supernova explosions may supply the required energy, there is growing evidence that they cannot explain all of the observed properties of cosmic rays, such as their maximum particle energy and isotopic composition. Among Galactic objects, winds from stellar clusters meet the energetic requirement and provide a suitable environment for particle acceleration. The recent detection of some of these objects in gamma rays confirms that they indeed harbor high-energy particles.However, as most supernovae explode inside stellar clusters, it is difficult to distinguish the contribution of winds to particle acceleration. Here we report the detection of young star clusters in the nearby Vela molecular ridge star forming region. The young age of the systems guarantees an unbiased estimate of the stellar CR luminosity free from any supernova or pulsar contamination and allows us to draw conclusions on the acceleration efficiency and the total power supplied by these objects. We demonstrate that much more than 1% of the wind mechanical power is converted into CRs and consequently conclude that a small but non-negligible fraction ~ 1-10% of the CR population is contributed by stellar clusters. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.07509v1-abstract-full').style.display = 'none'; document.getElementById('2407.07509v1-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 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 Manuscript version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nat Astron 8, 530-537 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.18167">arXiv:2406.18167</a> <span> [<a href="https://arxiv.org/pdf/2406.18167">pdf</a>, <a href="https://arxiv.org/format/2406.18167">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"> H.E.S.S. observations of the 2021 periastron passage of PSR B1259-63/LS 2883 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Collaboration%2C+H+E+S+S">H. E. S. S. Collaboration</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=Benkhali%2C+F+A">F. Ait Benkhali</a>, <a href="/search/?searchtype=author&query=Aschersleben%2C+J">J. Aschersleben</a>, <a href="/search/?searchtype=author&query=Ashkar%2C+H">H. Ashkar</a>, <a href="/search/?searchtype=author&query=Backes%2C+M">M. Backes</a>, <a href="/search/?searchtype=author&query=Martins%2C+V+B">V. Barbosa Martins</a>, <a href="/search/?searchtype=author&query=Batzofin%2C+R">R. Batzofin</a>, <a href="/search/?searchtype=author&query=Becherini%2C+Y">Y. Becherini</a>, <a href="/search/?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/?searchtype=author&query=Bernl%C3%B6hr%2C+K">K. Bernl枚hr</a>, <a href="/search/?searchtype=author&query=B%C3%B6ttcher%2C+M">M. B枚ttcher</a>, <a href="/search/?searchtype=author&query=Boisson%2C+C">C. Boisson</a>, <a href="/search/?searchtype=author&query=Bolmont%2C+J">J. Bolmont</a>, <a href="/search/?searchtype=author&query=de+Lavergne%2C+M+d+B">M. de Bony de Lavergne</a>, <a href="/search/?searchtype=author&query=Borowska%2C+J">J. Borowska</a>, <a href="/search/?searchtype=author&query=Bouyahiaoui%2C+M">M. Bouyahiaoui</a>, <a href="/search/?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/?searchtype=author&query=Brown%2C+A">A. Brown</a>, <a href="/search/?searchtype=author&query=Brun%2C+F">F. Brun</a>, <a href="/search/?searchtype=author&query=Bruno%2C+B">B. Bruno</a>, <a href="/search/?searchtype=author&query=Bulik%2C+T">T. Bulik</a>, <a href="/search/?searchtype=author&query=Burger-Scheidlin%2C+C">C. Burger-Scheidlin</a>, <a href="/search/?searchtype=author&query=Caroff%2C+S">S. Caroff</a>, <a href="/search/?searchtype=author&query=Casanova%2C+S">S. Casanova</a> , et al. (119 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="2406.18167v1-abstract-short" style="display: inline;"> PSR B1259-63 is a gamma-ray binary system that hosts a pulsar in an eccentric orbit, with a 3.4 year period, around an O9.5Ve star. At orbital phases close to periastron passages, the system radiates bright and variable non-thermal emission. We report on an extensive VHE observation campaign conducted with the High Energy Stereoscopic System, comprised of ~100 hours of data taken from $t_p-24$ day… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.18167v1-abstract-full').style.display = 'inline'; document.getElementById('2406.18167v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.18167v1-abstract-full" style="display: none;"> PSR B1259-63 is a gamma-ray binary system that hosts a pulsar in an eccentric orbit, with a 3.4 year period, around an O9.5Ve star. At orbital phases close to periastron passages, the system radiates bright and variable non-thermal emission. We report on an extensive VHE observation campaign conducted with the High Energy Stereoscopic System, comprised of ~100 hours of data taken from $t_p-24$ days to $t_p+127$ days around the system's 2021 periastron passage. We also present the timing and spectral analyses of the source. The VHE light curve in 2021 is consistent with the stacked light curve of all previous observations. Within the light curve, we report a VHE maximum at times coincident with the third X-ray peak first detected in the 2021 X-ray light curve. In the light curve -- although sparsely sampled in this time period -- we see no VHE enhancement during the second disc crossing. In addition, we see no correspondence to the 2021 GeV flare in the VHE light curve. The VHE spectrum obtained from the analysis of the 2021 dataset is best described by a power law of spectral index $螕= 2.65 \pm 0.04_{\text{stat}}$ $\pm 0.04_{\text{sys}}$, a value consistent with the previous H.E.S.S. observations of the source. We report spectral variability with a difference of $螖螕= 0.56 ~\pm~ 0.18_{\text{stat}}$ $~\pm~0.10_{\text{sys}}$ at 95% c.l., between sub-periods of the 2021 dataset. We also find a linear correlation between contemporaneous flux values of X-ray and TeV datasets, detected mainly after $t_p+25$ days, suggesting a change in the available energy for non-thermal radiation processes. We detect no significant correlation between GeV and TeV flux points, within the uncertainties of the measurements, from $\sim t_p-23$ days to $\sim t_p+126$ days. This suggests that the GeV and TeV emission originate from different electron populations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.18167v1-abstract-full').style.display = 'none'; document.getElementById('2406.18167v1-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 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">accepted to A&A</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.08698">arXiv:2406.08698</a> <span> [<a href="https://arxiv.org/pdf/2406.08698">pdf</a>, <a href="https://arxiv.org/format/2406.08698">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 - Phenomenology">hep-ph</span> </div> </div> <p class="title is-5 mathjax"> Constraints on Ultra Heavy Dark Matter Properties from Dwarf Spheroidal Galaxies with LHAASO Observations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=An%2C+Q">Q. An</a>, <a href="/search/?searchtype=author&query=Axikegu"> Axikegu</a>, <a href="/search/?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+Z">S. Z. Chen</a> , et al. (255 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="2406.08698v1-abstract-short" style="display: inline;"> In this work we try to search for signals generated by ultra-heavy dark matter at the Large High Altitude Air Shower Observatory (LHAASO) data. We look for possible gamma-ray by dark matter annihilation or decay from 16 dwarf spheroidal galaxies in the field of view of LHAASO. Dwarf spheroidal galaxies are among the most promising targets for indirect detection of dark matter which have low fluxes… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.08698v1-abstract-full').style.display = 'inline'; document.getElementById('2406.08698v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.08698v1-abstract-full" style="display: none;"> In this work we try to search for signals generated by ultra-heavy dark matter at the Large High Altitude Air Shower Observatory (LHAASO) data. We look for possible gamma-ray by dark matter annihilation or decay from 16 dwarf spheroidal galaxies in the field of view of LHAASO. Dwarf spheroidal galaxies are among the most promising targets for indirect detection of dark matter which have low fluxes of astrophysical $纬$-ray background while large amount of dark matter. By analyzing more than 700 days observational data at LHAASO, no significant dark matter signal from 1 TeV to 1 EeV is detected. Accordingly we derive the most stringent constraints on the ultra-heavy dark matter annihilation cross-section up to EeV. The constraints on the lifetime of dark matter in decay mode are also derived. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.08698v1-abstract-full').style.display = 'none'; document.getElementById('2406.08698v1-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 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, 12 figures, accepted by PRL</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.20927">arXiv:2405.20927</a> <span> [<a href="https://arxiv.org/pdf/2405.20927">pdf</a>, <a href="https://arxiv.org/format/2405.20927">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/10.1051/0004-6361/202451018">10.1051/0004-6361/202451018 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Search of extended emission from HESS J1702-420 with eROSITA </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Malyshev%2C+D">Denys Malyshev</a>, <a href="/search/?searchtype=author&query=Chernyakova%2C+M">Maria Chernyakova</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">Felix Aharonian</a>, <a href="/search/?searchtype=author&query=Santangelo%2C+A">Andrea Santangelo</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="2405.20927v2-abstract-short" style="display: inline;"> HESS J1702-420 is a peculiar TeV complex with a morphology changing from a diffuse (HESS J1702-420B source) at $\lesssim 2$ TeV to point-like (HESS J1702-420A) at $\gtrsim 10$ TeV energies. The morphology and the spectral properties of HESS J1702-420 could be understood in terms of a (diffusive) hadronic or leptonic models in which the observed TeV emission arises correpondingly from proton-proton… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.20927v2-abstract-full').style.display = 'inline'; document.getElementById('2405.20927v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.20927v2-abstract-full" style="display: none;"> HESS J1702-420 is a peculiar TeV complex with a morphology changing from a diffuse (HESS J1702-420B source) at $\lesssim 2$ TeV to point-like (HESS J1702-420A) at $\gtrsim 10$ TeV energies. The morphology and the spectral properties of HESS J1702-420 could be understood in terms of a (diffusive) hadronic or leptonic models in which the observed TeV emission arises correpondingly from proton-proton or IC-radiation of relativistic particles present in the region. In this work we perform searches of the X-ray counterpart of HESS J1702-420B source originated from the synchrotron emission of the primary or secondary relativistic electrons produced within leptonic or hadronic models. Such an emission can be extended and remain beyond the detection capabilities of a narrow-FoV instruments such as XMM-Newton. We utilise the publicly available first 6-months eROSITA dataset (DR1) fully covering selected for the analysis region of $> 5^\circ$-radius around HESS J1702-420. We discuss biases connected to variable plasma temperature/neutral hydrogen column density in the region and present results based on background modelling approach. The performed analysis does not allow us to detect the extended X-ray counterpart of HESS J1702-420 of $0.07^\circ - 3^\circ$-radii sizes. The derived upper limits are significantly higher than the expected hadronic model flux of the X-ray counterpart. For the leptonic model the derived limits indicate the magnetic field in the region $B\lesssim 2渭$G. We argue, that the further advances in the diffuse X-ray counterpart searches could be achieved either with next generation missions or Msec-long observational campaigns with currently operating instruments. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.20927v2-abstract-full').style.display = 'none'; document.getElementById('2405.20927v2-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 31 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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 to 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 690, A142 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.11826">arXiv:2405.11826</a> <span> [<a href="https://arxiv.org/pdf/2405.11826">pdf</a>, <a href="https://arxiv.org/format/2405.11826">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 Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> </div> </div> <p class="title is-5 mathjax"> Data quality control system and long-term performance monitor of the LHAASO-KM2A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=Axikegu"> Axikegu</a>, <a href="/search/?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/?searchtype=author&query=Bian%2C+W">W. Bian</a>, <a href="/search/?searchtype=author&query=Bukevich%2C+A+V">A. V. Bukevich</a>, <a href="/search/?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+H+X">H. X. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S">S. Chen</a> , et al. (263 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="2405.11826v3-abstract-short" style="display: inline;"> The KM2A is the largest sub-array of the Large High Altitude Air Shower Observatory (LHAASO). It consists of 5216 electromagnetic particle detectors (EDs) and 1188 muon detectors (MDs). The data recorded by the EDs and MDs are used to reconstruct primary information of cosmic ray and gamma-ray showers. This information is used for physical analysis in gamma-ray astronomy and cosmic ray physics. To… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.11826v3-abstract-full').style.display = 'inline'; document.getElementById('2405.11826v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.11826v3-abstract-full" style="display: none;"> The KM2A is the largest sub-array of the Large High Altitude Air Shower Observatory (LHAASO). It consists of 5216 electromagnetic particle detectors (EDs) and 1188 muon detectors (MDs). The data recorded by the EDs and MDs are used to reconstruct primary information of cosmic ray and gamma-ray showers. This information is used for physical analysis in gamma-ray astronomy and cosmic ray physics. To ensure the reliability of the LHAASO-KM2A data, a three-level quality control system has been established. It is used to monitor the status of detector units, stability of reconstructed parameters and the performance of the array based on observations of the Crab Nebula and Moon shadow. This paper will introduce the control system and its application on the LHAASO-KM2A data collected from August 2021 to July 2023. During this period, the pointing and angular resolution of the array were stable. From the observations of the Moon shadow and Crab Nebula, the results achieved using the two methods are consistent with each other. According to the observation of the Crab Nebula at energies from 25 TeV to 100 TeV, the time averaged pointing errors are estimated to be $-0.003^{\circ} \pm 0.005^{\circ}$ and $0.001^{\circ} \pm 0.006^{\circ}$ in the R.A. and Dec directions, respectively. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.11826v3-abstract-full').style.display = 'none'; document.getElementById('2405.11826v3-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 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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">15 pages, 9 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/2405.07691">arXiv:2405.07691</a> <span> [<a href="https://arxiv.org/pdf/2405.07691">pdf</a>, <a href="https://arxiv.org/format/2405.07691">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 Very-high-energy Gamma-ray Emissions from the Low Luminosity AGN NGC 4278 by LHAASO </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=An%2C+Q">Q. An</a>, <a href="/search/?searchtype=author&query=Axikegu"> Axikegu</a>, <a href="/search/?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+Z">S. Z. Chen</a> , et al. (255 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="2405.07691v1-abstract-short" style="display: inline;"> The first source catalog of Large High Altitude Air Shower Observatory reported the detection of a very-high-energy gamma ray source, 1LHAASO J1219+2915. In this paper a further detailed study of the spectral and temporal behavior of this point-like source have been carried. The best-fit position of the TeV source ($\rm{RA}=185.05^{\circ}\pm0.04^{\circ}$, $\rm{Dec}=29.25^{\circ}\pm0.03^{\circ}$) i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.07691v1-abstract-full').style.display = 'inline'; document.getElementById('2405.07691v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.07691v1-abstract-full" style="display: none;"> The first source catalog of Large High Altitude Air Shower Observatory reported the detection of a very-high-energy gamma ray source, 1LHAASO J1219+2915. In this paper a further detailed study of the spectral and temporal behavior of this point-like source have been carried. The best-fit position of the TeV source ($\rm{RA}=185.05^{\circ}\pm0.04^{\circ}$, $\rm{Dec}=29.25^{\circ}\pm0.03^{\circ}$) is compatible with NGC 4278 within $\sim0.03$ degree. Variation analysis shows an indication of the variability at a few months level in the TeV band, which is consistent with low frequency observations. Based on these observations, we report the detection of TeV $纬$-ray emissions from this low-luminosity AGN NGC 4278. The observations by LHAASO-WCDA during active period has a significance level of 8.8\,$蟽$ with best-fit photon spectral index $\varGamma=2.56\pm0.14$ and a flux $f_{1-10\,\rm{TeV}}=(7.0\pm1.1_{\rm{sta}}\pm0.35_{\rm{syst}})\times10^{-13}\,\rm{photons\,cm^{-2}\,s^{-1}}$, or approximately $5\%$ of the Crab Nebula. The discovery of VHE from NGC 4278 indicates that the compact, weak radio jet can efficiently accelerate particles and emit TeV photons. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.07691v1-abstract-full').style.display = 'none'; document.getElementById('2405.07691v1-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 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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">11 pages, 5 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/2405.05402">arXiv:2405.05402</a> <span> [<a href="https://arxiv.org/pdf/2405.05402">pdf</a>, <a href="https://arxiv.org/format/2405.05402">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"> The possibility of multi-TeV secondary gamma rays from GRB221009A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Kalashev%2C+O">Oleg Kalashev</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">Felix Aharonian</a>, <a href="/search/?searchtype=author&query=Essey%2C+W">Warren Essey</a>, <a href="/search/?searchtype=author&query=Inoue%2C+Y">Yoshiyuki Inoue</a>, <a href="/search/?searchtype=author&query=Kusenko%2C+A">Alexander Kusenko</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="2405.05402v1-abstract-short" style="display: inline;"> The brightest gamma ray burst (GRB) ever observed, GRB221009A, produced a surprisingly large flux of gamma rays with multi-TeV energies, which are expected to be absorbed in interactions with extragalactic background light (EBL). If the highest energy gamma rays were produced at the source, their spectral shape would have to exhibit a nonphysical spike even for the lowest levels of EBL. We show th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.05402v1-abstract-full').style.display = 'inline'; document.getElementById('2405.05402v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.05402v1-abstract-full" style="display: none;"> The brightest gamma ray burst (GRB) ever observed, GRB221009A, produced a surprisingly large flux of gamma rays with multi-TeV energies, which are expected to be absorbed in interactions with extragalactic background light (EBL). If the highest energy gamma rays were produced at the source, their spectral shape would have to exhibit a nonphysical spike even for the lowest levels of EBL. We show that, for widely accepted models of EBL, the data can be explained by secondary gamma rays produced in cosmic ray interactions along the line of sight, as long as the extragalactic magnetic fields (EGMFs) are $10^{-16}$G or smaller, assuming 1 Mpc correlation length. Our interpretation supports the widely held expectation that GRB jets can accelerate cosmic rays to energies as high as 10 EeV and above, and it has implications for understanding the magnitudes of EGMFs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.05402v1-abstract-full').style.display = 'none'; document.getElementById('2405.05402v1-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 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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">6 pages, 3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> INR-TH-2024-007 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.16591">arXiv:2404.16591</a> <span> [<a href="https://arxiv.org/pdf/2404.16591">pdf</a>, <a href="https://arxiv.org/format/2404.16591">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"> The hunt of PeVatrons as the origin of the most energetic photons observed in our Galaxy </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Wilhelmi%2C+E+d+O">Emma de O帽a Wilhelmi</a>, <a href="/search/?searchtype=author&query=L%C3%B3pez-Coto%2C+R">Rub茅n L贸pez-Coto</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">Felix Aharonian</a>, <a href="/search/?searchtype=author&query=Amato%2C+E">Elena Amato</a>, <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/?searchtype=author&query=Gabici%2C+S">Stefano Gabici</a>, <a href="/search/?searchtype=author&query=Hinton%2C+J">Jim Hinton</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="2404.16591v1-abstract-short" style="display: inline;"> Ultrarelativistic particles called cosmic rays permeate the Milky Way, propagating through the Galactic turbulent magnetic fields. The mechanisms under which these particles increase their energy can be reasonably described by current theories of acceleration and propagation of cosmic rays. There are, however, still many open questions as to how to reach petaelectronvolt (PeV) energies, the maximu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.16591v1-abstract-full').style.display = 'inline'; document.getElementById('2404.16591v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.16591v1-abstract-full" style="display: none;"> Ultrarelativistic particles called cosmic rays permeate the Milky Way, propagating through the Galactic turbulent magnetic fields. The mechanisms under which these particles increase their energy can be reasonably described by current theories of acceleration and propagation of cosmic rays. There are, however, still many open questions as to how to reach petaelectronvolt (PeV) energies, the maximum energy believed to be attained in our Galaxy, and in which astrophysical sources (dubbed {\it PeVatrons}) this ultra-high energy acceleration happens. In this article, we describe the theoretical conditions for plasma acceleration to these energies, and the Galactic sources in which these conditions are possible. These theoretical predictions are then confronted with the latest experimental results, summarising the state-of-the-art of our current knowledge of PeVatrons. We finally describe the prospects to keep advancing the understanding of these elusive objects, still unidentified more than one hundred years after the discovery of cosmic rays. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.16591v1-abstract-full').style.display = 'none'; document.getElementById('2404.16591v1-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 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">Published in Nature Astronomy, Volume 8, pages 425-431 (2024)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.11012">arXiv:2404.11012</a> <span> [<a href="https://arxiv.org/pdf/2404.11012">pdf</a>, <a href="https://arxiv.org/format/2404.11012">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"> Search for synchrotron emission from secondary electrons of proton-proton interaction in Galactic PeVatron candidate HESS J1641$-$463 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Tsuji%2C+N">Naomi Tsuji</a>, <a href="/search/?searchtype=author&query=Tanaka%2C+T">Takaaki Tanaka</a>, <a href="/search/?searchtype=author&query=Safi-Harb%2C+S">Samar Safi-Harb</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">Felix Aharonian</a>, <a href="/search/?searchtype=author&query=Casanova%2C+S">Sabrina Casanova</a>, <a href="/search/?searchtype=author&query=Kothes%2C+R">Roland Kothes</a>, <a href="/search/?searchtype=author&query=Moulin%2C+E">Emmanuel Moulin</a>, <a href="/search/?searchtype=author&query=Uchida%2C+H">Hiroyuki Uchida</a>, <a href="/search/?searchtype=author&query=Uchiyama%2C+Y">Yasunobu Uchiyama</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="2404.11012v1-abstract-short" style="display: inline;"> HESS J1641-463 is an unidentified gamma-ray source with a hard TeV gamma-ray spectrum, and thus it has been proposed to be a possible candidate for cosmic ray (CR) accelerators up to PeV energies (a PeVatron candidate). The source spatially coincides with the radio supernova remnant (SNR) G338.5+0.1, but has not yet been fully explored in the X-ray band. We analyzed newly taken NuSTAR data, pointi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.11012v1-abstract-full').style.display = 'inline'; document.getElementById('2404.11012v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.11012v1-abstract-full" style="display: none;"> HESS J1641-463 is an unidentified gamma-ray source with a hard TeV gamma-ray spectrum, and thus it has been proposed to be a possible candidate for cosmic ray (CR) accelerators up to PeV energies (a PeVatron candidate). The source spatially coincides with the radio supernova remnant (SNR) G338.5+0.1, but has not yet been fully explored in the X-ray band. We analyzed newly taken NuSTAR data, pointing at HESS J1641-463, with 82 ks effective exposure time. There is no apparent X-ray counterpart of HESS J1641-463, while nearby stellar cluster, Mercer 81, and stray-light X-rays are detected. Combined with the archival Chandra data, partially covering the source, we derived an upper limit of $\sim 6\times 10^{-13}$ erg cm$^{-2}$ s$^{-1}$ in 2-10 keV ($\sim 3\times 10^{-13}$ erg cm$^{-2}$ s$^{-1}$ in 10-20 keV). If the gamma-ray emission is originated from decay of $蟺^0$ mesons produced in interactions between CR protons and ambient materials, secondary electrons in the proton-proton interactions can potentially emit synchrotron photons in the X-ray band, which can be tested by our X-ray observations. Although the obtained X-ray upper limits cannot place a constraint on the primary proton spectrum, it will be possible with a future hard X-ray mission. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.11012v1-abstract-full').style.display = 'none'; document.getElementById('2404.11012v1-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> 16 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">15 pages, 8 figures, 4 tables, accepted for publication in ApJ</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> RIKEN-iTHEMS-Report-(24) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.04801">arXiv:2404.04801</a> <span> [<a href="https://arxiv.org/pdf/2404.04801">pdf</a>, <a href="https://arxiv.org/ps/2404.04801">ps</a>, <a href="https://arxiv.org/format/2404.04801">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/10.1007/s41605-024-00467-8">10.1007/s41605-024-00467-8 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> LHAASO-KM2A detector simulation using Geant4 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=An%2C+Q">Q. An</a>, <a href="/search/?searchtype=author&query=Axikegu"> Axikegu</a>, <a href="/search/?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+Z">S. Z. Chen</a> , et al. (254 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="2404.04801v1-abstract-short" style="display: inline;"> KM2A is one of the main sub-arrays of LHAASO, working on gamma ray astronomy and cosmic ray physics at energies above 10 TeV. Detector simulation is the important foundation for estimating detector performance and data analysis. It is a big challenge to simulate the KM2A detector in the framework of Geant4 due to the need to track numerous photons from a large number of detector units (>6000) with… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.04801v1-abstract-full').style.display = 'inline'; document.getElementById('2404.04801v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.04801v1-abstract-full" style="display: none;"> KM2A is one of the main sub-arrays of LHAASO, working on gamma ray astronomy and cosmic ray physics at energies above 10 TeV. Detector simulation is the important foundation for estimating detector performance and data analysis. It is a big challenge to simulate the KM2A detector in the framework of Geant4 due to the need to track numerous photons from a large number of detector units (>6000) with large altitude difference (30 m) and huge coverage (1.3 km^2). In this paper, the design of the KM2A simulation code G4KM2A based on Geant4 is introduced. The process of G4KM2A is optimized mainly in memory consumption to avoid memory overffow. Some simpliffcations are used to signiffcantly speed up the execution of G4KM2A. The running time is reduced by at least 30 times compared to full detector simulation. The particle distributions and the core/angle resolution comparison between simulation and experimental data of the full KM2A array are also presented, which show good agreement. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.04801v1-abstract-full').style.display = 'none'; document.getElementById('2404.04801v1-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> 7 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.16802">arXiv:2403.16802</a> <span> [<a href="https://arxiv.org/pdf/2403.16802">pdf</a>, <a href="https://arxiv.org/format/2403.16802">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/10.1051/0004-6361/202348374">10.1051/0004-6361/202348374 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Unveiling extended gamma-ray emission around HESS J1813-178 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=Benkhali%2C+F+A">F. Ait Benkhali</a>, <a href="/search/?searchtype=author&query=Aschersleben%2C+J">J. Aschersleben</a>, <a href="/search/?searchtype=author&query=Ashkar%2C+H">H. Ashkar</a>, <a href="/search/?searchtype=author&query=Backes%2C+M">M. Backes</a>, <a href="/search/?searchtype=author&query=Baktash%2C+A">A. Baktash</a>, <a href="/search/?searchtype=author&query=Martins%2C+V+B">V. Barbosa Martins</a>, <a href="/search/?searchtype=author&query=Barnard%2C+J">J. Barnard</a>, <a href="/search/?searchtype=author&query=Batzofin%2C+R">R. Batzofin</a>, <a href="/search/?searchtype=author&query=Becherini%2C+Y">Y. Becherini</a>, <a href="/search/?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/?searchtype=author&query=Bernl%C3%B6hr%2C+K">K. Bernl枚hr</a>, <a href="/search/?searchtype=author&query=Bi%2C+B">B. Bi</a>, <a href="/search/?searchtype=author&query=B%C3%B6ttcher%2C+M">M. B枚ttcher</a>, <a href="/search/?searchtype=author&query=Boisson%2C+C">C. Boisson</a>, <a href="/search/?searchtype=author&query=Bolmont%2C+J">J. Bolmont</a>, <a href="/search/?searchtype=author&query=de+Lavergne%2C+M+d+B">M. de Bony de Lavergne</a>, <a href="/search/?searchtype=author&query=Borowska%2C+J">J. Borowska</a>, <a href="/search/?searchtype=author&query=Bouyahiaoui%2C+M">M. Bouyahiaoui</a>, <a href="/search/?searchtype=author&query=Breuhaus%2C+M">M. Breuhaus</a>, <a href="/search/?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/?searchtype=author&query=Brun%2C+F">F. Brun</a>, <a href="/search/?searchtype=author&query=Bruno%2C+B">B. Bruno</a>, <a href="/search/?searchtype=author&query=Bulik%2C+T">T. Bulik</a>, <a href="/search/?searchtype=author&query=Burger-Scheidlin%2C+C">C. Burger-Scheidlin</a> , et al. (126 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="2403.16802v1-abstract-short" style="display: inline;"> HESS J1813$-$178 is a very-high-energy $纬$-ray source spatially coincident with the young and energetic pulsar PSR J1813$-$1749 and thought to be associated with its pulsar wind nebula (PWN). Recently, evidence for extended high-energy emission in the vicinity of the pulsar has been revealed in the Fermi Large Area Telescope (LAT) data. This motivates revisiting the HESS J1813$-$178 region, taking… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.16802v1-abstract-full').style.display = 'inline'; document.getElementById('2403.16802v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.16802v1-abstract-full" style="display: none;"> HESS J1813$-$178 is a very-high-energy $纬$-ray source spatially coincident with the young and energetic pulsar PSR J1813$-$1749 and thought to be associated with its pulsar wind nebula (PWN). Recently, evidence for extended high-energy emission in the vicinity of the pulsar has been revealed in the Fermi Large Area Telescope (LAT) data. This motivates revisiting the HESS J1813$-$178 region, taking advantage of improved analysis methods and an extended data set. Using data taken by the High Energy Stereoscopic System (H.E.S.S.) experiment and the Fermi-LAT, we aim to describe the $纬$-ray emission in the region with a consistent model, to provide insights into its origin. We performed a likelihood-based analysis on 32 hours of H.E.S.S. data and 12 years of Fermi-LAT data and fit a spectro-morphological model to the combined datasets. These results allowed us to develop a physical model for the origin of the observed $纬$-ray emission in the region. In addition to the compact very-high-energy $纬$-ray emission centered on the pulsar, we find a significant yet previously undetected component along the Galactic plane. With Fermi-LAT data, we confirm extended high-energy emission consistent with the position and elongation of the extended emission observed with H.E.S.S. These results establish a consistent description of the emission in the region from GeV energies to several tens of TeV. This study suggests that HESS J1813$-$178 is associated with a $纬$-ray PWN powered by PSR J1813$-$1749. A possible origin of the extended emission component is inverse Compton emission from electrons and positrons that have escaped the confines of the pulsar and form a halo around the PWN. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.16802v1-abstract-full').style.display = 'none'; document.getElementById('2403.16802v1-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 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">13+5 pages, 13+11 figures. Accepted for publication in A&A. Corresponding authors: T.Wach, A.Mitchell, V.Joshi, P.Chamb茅ry</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 686, A149 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.12608">arXiv:2403.12608</a> <span> [<a href="https://arxiv.org/pdf/2403.12608">pdf</a>, <a href="https://arxiv.org/format/2403.12608">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/10.1051/0004-6361/202348651">10.1051/0004-6361/202348651 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Spectrum and extension of the inverse-Compton emission of the Crab Nebula from a combined Fermi-LAT and H.E.S.S. analysis </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=Benkhali%2C+F+A">F. Ait Benkhali</a>, <a href="/search/?searchtype=author&query=Aschersleben%2C+J">J. Aschersleben</a>, <a href="/search/?searchtype=author&query=Ashkar%2C+H">H. Ashkar</a>, <a href="/search/?searchtype=author&query=Backes%2C+M">M. Backes</a>, <a href="/search/?searchtype=author&query=Baktash%2C+A">A. Baktash</a>, <a href="/search/?searchtype=author&query=Martins%2C+V+B">V. Barbosa Martins</a>, <a href="/search/?searchtype=author&query=Batzofin%2C+R">R. Batzofin</a>, <a href="/search/?searchtype=author&query=Becherini%2C+Y">Y. Becherini</a>, <a href="/search/?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/?searchtype=author&query=Bernl%C3%B6hr%2C+K">K. Bernl枚hr</a>, <a href="/search/?searchtype=author&query=Bi%2C+B">B. Bi</a>, <a href="/search/?searchtype=author&query=B%C3%B6ttcher%2C+M">M. B枚ttcher</a>, <a href="/search/?searchtype=author&query=Boisson%2C+C">C. Boisson</a>, <a href="/search/?searchtype=author&query=Bolmont%2C+J">J. Bolmont</a>, <a href="/search/?searchtype=author&query=de+Lavergne%2C+M+d+B">M. de Bony de Lavergne</a>, <a href="/search/?searchtype=author&query=Borowska%2C+J">J. Borowska</a>, <a href="/search/?searchtype=author&query=Bradascio%2C+F">F. Bradascio</a>, <a href="/search/?searchtype=author&query=Breuhaus%2C+M">M. Breuhaus</a>, <a href="/search/?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/?searchtype=author&query=Brown%2C+A">A. Brown</a>, <a href="/search/?searchtype=author&query=Brun%2C+F">F. Brun</a>, <a href="/search/?searchtype=author&query=Bruno%2C+B">B. Bruno</a>, <a href="/search/?searchtype=author&query=Bulik%2C+T">T. Bulik</a>, <a href="/search/?searchtype=author&query=Burger-Scheidlin%2C+C">C. Burger-Scheidlin</a> , et al. (137 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="2403.12608v2-abstract-short" style="display: inline;"> The Crab Nebula is a unique laboratory for studying the acceleration of electrons and positrons through their non-thermal radiation. Observations of very-high-energy $纬$ rays from the Crab Nebula have provided important constraints for modelling its broadband emission. We present the first fully self-consistent analysis of the Crab Nebula's $纬$-ray emission between 1 GeV and $\sim$100 TeV, that is… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.12608v2-abstract-full').style.display = 'inline'; document.getElementById('2403.12608v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.12608v2-abstract-full" style="display: none;"> The Crab Nebula is a unique laboratory for studying the acceleration of electrons and positrons through their non-thermal radiation. Observations of very-high-energy $纬$ rays from the Crab Nebula have provided important constraints for modelling its broadband emission. We present the first fully self-consistent analysis of the Crab Nebula's $纬$-ray emission between 1 GeV and $\sim$100 TeV, that is, over five orders of magnitude in energy. Using the open-source software package Gammapy, we combined 11.4 yr of data from the Fermi Large Area Telescope and 80 h of High Energy Stereoscopic System (H.E.S.S.) data at the event level and provide a measurement of the spatial extension of the nebula and its energy spectrum. We find evidence for a shrinking of the nebula with increasing $纬$-ray energy. Furthermore, we fitted several phenomenological models to the measured data, finding that none of them can fully describe the spatial extension and the spectral energy distribution at the same time. Especially the extension measured at TeV energies appears too large when compared to the X-ray emission. Our measurements probe the structure of the magnetic field between the pulsar wind termination shock and the dust torus, and we conclude that the magnetic field strength decreases with increasing distance from the pulsar. We complement our study with a careful assessment of systematic uncertainties. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.12608v2-abstract-full').style.display = 'none'; document.getElementById('2403.12608v2-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> 21 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 19 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">18+6 pages, 15+2 figures. Accepted for publication in A&A. Corresponding authors: M. Meyer, L. Mohrmann, T. Unbehaun. v2: after A&A language editing</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 686, A308 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.10010">arXiv:2403.10010</a> <span> [<a href="https://arxiv.org/pdf/2403.10010">pdf</a>, <a href="https://arxiv.org/format/2403.10010">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/10.1103/PhysRevLett.132.131002">10.1103/PhysRevLett.132.131002 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Measurements of All-Particle Energy Spectrum and Mean Logarithmic Mass of Cosmic Rays from 0.3 to 30 PeV with LHAASO-KM2A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=The+LHAASO+Collaboration"> The LHAASO Collaboration</a>, <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=An%2C+Q">Q. An</a>, <a href="/search/?searchtype=author&query=Axikegu%2C+A">A. Axikegu</a>, <a href="/search/?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a> , et al. (256 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="2403.10010v2-abstract-short" style="display: inline;"> We present the measurements of all-particle energy spectrum and mean logarithmic mass of cosmic rays in the energy range of 0.3-30 PeV using data collected from LHAASO-KM2A between September 2021 and December 2022, which is based on a nearly composition-independent energy reconstruction method, achieving unprecedented accuracy. Our analysis reveals the position of the knee at… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.10010v2-abstract-full').style.display = 'inline'; document.getElementById('2403.10010v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.10010v2-abstract-full" style="display: none;"> We present the measurements of all-particle energy spectrum and mean logarithmic mass of cosmic rays in the energy range of 0.3-30 PeV using data collected from LHAASO-KM2A between September 2021 and December 2022, which is based on a nearly composition-independent energy reconstruction method, achieving unprecedented accuracy. Our analysis reveals the position of the knee at $3.67 \pm 0.05 \pm 0.15$ PeV. Below the knee, the spectral index is found to be -$2.7413 \pm 0.0004 \pm 0.0050$, while above the knee, it is -$3.128 \pm 0.005 \pm 0.027$, with the sharpness of the transition measured with a statistical error of 2%. The mean logarithmic mass of cosmic rays is almost heavier than helium in the whole measured energy range. It decreases from 1.7 at 0.3 PeV to 1.3 at 3 PeV, representing a 24% decline following a power law with an index of -$0.1200 \pm 0.0003 \pm 0.0341$. This is equivalent to an increase in abundance of light components. Above the knee, the mean logarithmic mass exhibits a power law trend towards heavier components, which is reversal to the behavior observed in the all-particle energy spectrum. Additionally, the knee position and the change in power-law index are approximately the same. These findings suggest that the knee observed in the all-particle spectrum corresponds to the knee of the light component, rather than the medium-heavy components. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.10010v2-abstract-full').style.display = 'none'; document.getElementById('2403.10010v2-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 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 15 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">8 pages, 3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physical Review Letters 132, 131002 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.13330">arXiv:2402.13330</a> <span> [<a href="https://arxiv.org/pdf/2402.13330">pdf</a>, <a href="https://arxiv.org/format/2402.13330">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/10.1051/0004-6361/202348913">10.1051/0004-6361/202348913 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Curvature in the very-high energy gamma-ray spectrum of M87 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Collaboration%2C+H+E+S+S">H. E. S. S. Collaboration</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=Benkhali%2C+F+A">F. Ait Benkhali</a>, <a href="/search/?searchtype=author&query=Aschersleben%2C+J">J. Aschersleben</a>, <a href="/search/?searchtype=author&query=Ashkar%2C+H">H. Ashkar</a>, <a href="/search/?searchtype=author&query=Backes%2C+M">M. Backes</a>, <a href="/search/?searchtype=author&query=Martins%2C+V+B">V. Barbosa Martins</a>, <a href="/search/?searchtype=author&query=Batzofin%2C+R">R. Batzofin</a>, <a href="/search/?searchtype=author&query=Becherini%2C+Y">Y. Becherini</a>, <a href="/search/?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/?searchtype=author&query=Bernl%C3%B6hr%2C+K">K. Bernl枚hr</a>, <a href="/search/?searchtype=author&query=B%C3%B6ttcher%2C+M">M. B枚ttcher</a>, <a href="/search/?searchtype=author&query=Boisson%2C+C">C. Boisson</a>, <a href="/search/?searchtype=author&query=Bolmont%2C+J">J. Bolmont</a>, <a href="/search/?searchtype=author&query=de+Lavergne%2C+M+d+B">M. de Bony de Lavergne</a>, <a href="/search/?searchtype=author&query=Bradascio%2C+F">F. Bradascio</a>, <a href="/search/?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/?searchtype=author&query=Brun%2C+F">F. Brun</a>, <a href="/search/?searchtype=author&query=Bruno%2C+B">B. Bruno</a>, <a href="/search/?searchtype=author&query=Burger-Scheidlin%2C+T+B+C">T. Bulik C. Burger-Scheidlin</a>, <a href="/search/?searchtype=author&query=Bylund%2C+T">T. Bylund</a>, <a href="/search/?searchtype=author&query=Casanova%2C+S">S. Casanova</a>, <a href="/search/?searchtype=author&query=Cecil%2C+R">R. Cecil</a>, <a href="/search/?searchtype=author&query=Celic%2C+J">J. Celic</a>, <a href="/search/?searchtype=author&query=Cerruti%2C+M">M. Cerruti</a> , et al. (110 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="2402.13330v3-abstract-short" style="display: inline;"> The radio galaxy M87 is a variable very-high energy (VHE) gamma-ray source, exhibiting three major flares reported in 2005, 2008, and 2010. Despite extensive studies, the origin of the VHE gamma-ray emission is yet to be understood. In this study, we investigate the VHE gamma-ray spectrum of M87 during states of high gamma-ray activity, utilizing 20.2$\,$ hours the H.E.S.S. observations. Our findi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.13330v3-abstract-full').style.display = 'inline'; document.getElementById('2402.13330v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.13330v3-abstract-full" style="display: none;"> The radio galaxy M87 is a variable very-high energy (VHE) gamma-ray source, exhibiting three major flares reported in 2005, 2008, and 2010. Despite extensive studies, the origin of the VHE gamma-ray emission is yet to be understood. In this study, we investigate the VHE gamma-ray spectrum of M87 during states of high gamma-ray activity, utilizing 20.2$\,$ hours the H.E.S.S. observations. Our findings indicate a preference for a curved spectrum, characterized by a log-parabola model with extra-galactic background light (EBL) model above 0.3$\,$TeV at the 4$蟽$ level, compared to a power-law spectrum with EBL. We investigate the degeneracy between the absorption feature and the EBL normalization and derive upper limits on EBL models mainly sensitive in the wavelength range 12.4$\,$$渭$m - 40$\,$$渭$m. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.13330v3-abstract-full').style.display = 'none'; document.getElementById('2402.13330v3-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 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 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">10 pages, 7 figures. Accepted for publication in A&A. Corresponding authors: Victor Barbosa Martins, Rahul Cecil, Iryna Lypova, Manuel Meyer, Perri Zilberman. Supplementary material: https://zenodo.org/records/10781524</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A, 685, A96 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.16019">arXiv:2401.16019</a> <span> [<a href="https://arxiv.org/pdf/2401.16019">pdf</a>, <a href="https://arxiv.org/format/2401.16019">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/10.1126/science.adi2048">10.1126/science.adi2048 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Acceleration and transport of relativistic electrons in the jets of the microquasar SS 433 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=Benkhali%2C+F+A">F. Ait Benkhali</a>, <a href="/search/?searchtype=author&query=Aschersleben%2C+J">J. Aschersleben</a>, <a href="/search/?searchtype=author&query=Ashkar%2C+H">H. Ashkar</a>, <a href="/search/?searchtype=author&query=Backes%2C+M">M. Backes</a>, <a href="/search/?searchtype=author&query=Martins%2C+V+B">V. Barbosa Martins</a>, <a href="/search/?searchtype=author&query=Batzofin%2C+R">R. Batzofin</a>, <a href="/search/?searchtype=author&query=Becherini%2C+Y">Y. Becherini</a>, <a href="/search/?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/?searchtype=author&query=Bernl%C3%B6hr%2C+K">K. Bernl枚hr</a>, <a href="/search/?searchtype=author&query=Bi%2C+B">B. Bi</a>, <a href="/search/?searchtype=author&query=B%C3%B6ttcher%2C+M">M. B枚ttcher</a>, <a href="/search/?searchtype=author&query=Boisson%2C+C">C. Boisson</a>, <a href="/search/?searchtype=author&query=Bolmont%2C+J">J. Bolmont</a>, <a href="/search/?searchtype=author&query=de+Lavergne%2C+M+d+B">M. de Bony de Lavergne</a>, <a href="/search/?searchtype=author&query=Borowska%2C+J">J. Borowska</a>, <a href="/search/?searchtype=author&query=Bouyahiaou%2C+M">M. Bouyahiaou</a>, <a href="/search/?searchtype=author&query=Breuhau%2C+M">M. Breuhau</a>, <a href="/search/?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/?searchtype=author&query=Brown%2C+A+M">A. M. Brown</a>, <a href="/search/?searchtype=author&query=Brun%2C+F">F. Brun</a>, <a href="/search/?searchtype=author&query=Bruno%2C+B">B. Bruno</a>, <a href="/search/?searchtype=author&query=Bulik%2C+T">T. Bulik</a>, <a href="/search/?searchtype=author&query=Burger-Scheidlin%2C+C">C. Burger-Scheidlin</a>, <a href="/search/?searchtype=author&query=Caroff%2C+S">S. Caroff</a> , et al. (140 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="2401.16019v1-abstract-short" style="display: inline;"> SS 433 is a microquasar, a stellar binary system with collimated relativistic jets. We observed SS 433 in gamma rays using the High Energy Stereoscopic System (H.E.S.S.), finding an energy-dependent shift in the apparent position of the gamma-ray emission of the parsec-scale jets. These observations trace the energetic electron population and indicate the gamma rays are produced by inverse-Compton… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.16019v1-abstract-full').style.display = 'inline'; document.getElementById('2401.16019v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.16019v1-abstract-full" style="display: none;"> SS 433 is a microquasar, a stellar binary system with collimated relativistic jets. We observed SS 433 in gamma rays using the High Energy Stereoscopic System (H.E.S.S.), finding an energy-dependent shift in the apparent position of the gamma-ray emission of the parsec-scale jets. These observations trace the energetic electron population and indicate the gamma rays are produced by inverse-Compton scattering. Modelling of the energy-dependent gamma-ray morphology constrains the location of particle acceleration and requires an abrupt deceleration of the jet flow. We infer the presence of shocks on either side of the binary system at distances of 25 to 30 parsecs and conclude that self-collimation of the precessing jets forms the shocks, which then efficiently accelerate electrons. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.16019v1-abstract-full').style.display = 'none'; document.getElementById('2401.16019v1-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> 29 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">Submitted 20th Apr. 2023, published 25th January 2024 (accepted version)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Science383,402-406(2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.07071">arXiv:2401.07071</a> <span> [<a href="https://arxiv.org/pdf/2401.07071">pdf</a>, <a href="https://arxiv.org/format/2401.07071">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"> TeV flaring activity of the AGN PKS 0625-354 in November 2018 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Collaboration%2C+H+E+S+S">H. E. S. S. Collaboration</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=Benkhali%2C+F+A">F. Ait Benkhali</a>, <a href="/search/?searchtype=author&query=Aschersleben%2C+J">J. Aschersleben</a>, <a href="/search/?searchtype=author&query=Ashkar%2C+H">H. Ashkar</a>, <a href="/search/?searchtype=author&query=Backes%2C+M">M. Backes</a>, <a href="/search/?searchtype=author&query=Baktash%2C+A">A. Baktash</a>, <a href="/search/?searchtype=author&query=Martins%2C+V+B">V. Barbosa Martins</a>, <a href="/search/?searchtype=author&query=Barnard%2C+J">J. Barnard</a>, <a href="/search/?searchtype=author&query=Batzofin%2C+R">R. Batzofin</a>, <a href="/search/?searchtype=author&query=Becherini%2C+Y">Y. Becherini</a>, <a href="/search/?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/?searchtype=author&query=Bernl%C3%B6hr%2C+K">K. Bernl枚hr</a>, <a href="/search/?searchtype=author&query=Bi%2C+B">B. Bi</a>, <a href="/search/?searchtype=author&query=B%C3%B6ttcher%2C+M">M. B枚ttcher</a>, <a href="/search/?searchtype=author&query=Boisson%2C+C">C. Boisson</a>, <a href="/search/?searchtype=author&query=Bolmont%2C+J">J. Bolmont</a>, <a href="/search/?searchtype=author&query=de+Lavergne%2C+M+d+B">M. de Bony de Lavergne</a>, <a href="/search/?searchtype=author&query=Borowska%2C+J">J. Borowska</a>, <a href="/search/?searchtype=author&query=Bradascio%2C+F">F. Bradascio</a>, <a href="/search/?searchtype=author&query=Breuhaus%2C+M">M. Breuhaus</a>, <a href="/search/?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/?searchtype=author&query=Brown%2C+A">A. Brown</a>, <a href="/search/?searchtype=author&query=Brun%2C+F">F. Brun</a>, <a href="/search/?searchtype=author&query=Bruno%2C+B">B. Bruno</a> , et al. (117 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="2401.07071v1-abstract-short" style="display: inline;"> Most $纬$-ray detected active galactic nuclei are blazars with one of their relativistic jets pointing towards the Earth. Only a few objects belong to the class of radio galaxies or misaligned blazars. Here, we investigate the nature of the object PKS 0625-354, its $纬$-ray flux and spectral variability and its broad-band spectral emission with observations from H.E.S.S., Fermi-LAT, Swift-XRT, and U… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.07071v1-abstract-full').style.display = 'inline'; document.getElementById('2401.07071v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.07071v1-abstract-full" style="display: none;"> Most $纬$-ray detected active galactic nuclei are blazars with one of their relativistic jets pointing towards the Earth. Only a few objects belong to the class of radio galaxies or misaligned blazars. Here, we investigate the nature of the object PKS 0625-354, its $纬$-ray flux and spectral variability and its broad-band spectral emission with observations from H.E.S.S., Fermi-LAT, Swift-XRT, and UVOT taken in November 2018. The H.E.S.S. light curve above 200 GeV shows an outburst in the first night of observations followed by a declining flux with a halving time scale of 5.9h. The $纬纬$-opacity constrains the upper limit of the angle between the jet and the line of sight to $\sim10^\circ$. The broad-band spectral energy distribution shows two humps and can be well fitted with a single-zone synchrotron self Compton emission model. We conclude that PKS 0625-354, as an object showing clear features of both blazars and radio galaxies, can be classified as an intermediate active galactic nuclei. Multi-wavelength studies of such intermediate objects exhibiting features of both blazars and radio galaxies are sparse but crucial for the understanding of the broad-band emission of $纬$-ray detected active galactic nuclei in general. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.07071v1-abstract-full').style.display = 'none'; document.getElementById('2401.07071v1-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, 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">9 pages, 6 figures, accepted for publication in Astronomy & Astrophysics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.17082">arXiv:2310.17082</a> <span> [<a href="https://arxiv.org/pdf/2310.17082">pdf</a>, <a href="https://arxiv.org/ps/2310.17082">ps</a>, <a href="https://arxiv.org/format/2310.17082">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"> Does or did the supernova remnant Cassiopeia A operate as a PeVatron? </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=An%2C+Q">Q. An</a>, <a href="/search/?searchtype=author&query=Axikegu"> Axikegu</a>, <a href="/search/?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+Z">S. Z. Chen</a> , et al. (255 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="2310.17082v1-abstract-short" style="display: inline;"> For decades, supernova remnants (SNRs) have been considered the prime sources of Galactic Cosmic rays (CRs). But whether SNRs can accelerate CR protons to PeV energies and thus dominate CR flux up to the knee is currently under intensive theoretical and phenomenological debate. The direct test of the ability of SNRs to operate as CR PeVatrons can be provided by ultrahigh-energy (UHE;… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.17082v1-abstract-full').style.display = 'inline'; document.getElementById('2310.17082v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.17082v1-abstract-full" style="display: none;"> For decades, supernova remnants (SNRs) have been considered the prime sources of Galactic Cosmic rays (CRs). But whether SNRs can accelerate CR protons to PeV energies and thus dominate CR flux up to the knee is currently under intensive theoretical and phenomenological debate. The direct test of the ability of SNRs to operate as CR PeVatrons can be provided by ultrahigh-energy (UHE; $E_纬\geq 100$~TeV) $纬$-rays. In this context, the historical SNR Cassiopeia A (Cas A) is considered one of the most promising target for UHE observations. This paper presents the observation of Cas A and its vicinity by the LHAASO KM2A detector. The exceptional sensitivity of LHAASO KM2A in the UHE band, combined with the young age of Cas A, enabled us to derive stringent model-independent limits on the energy budget of UHE protons and nuclei accelerated by Cas A at any epoch after the explosion. The results challenge the prevailing paradigm that Cas A-type SNRs are major suppliers of PeV CRs in the Milky Way. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.17082v1-abstract-full').style.display = 'none'; document.getElementById('2310.17082v1-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, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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">11 pages, 3 figures, Accepted by the APJL</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.08845">arXiv:2310.08845</a> <span> [<a href="https://arxiv.org/pdf/2310.08845">pdf</a>, <a href="https://arxiv.org/format/2310.08845">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/10.1126/sciadv.adj2778">10.1126/sciadv.adj2778 <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 emission beyond 10 TeV from GRB 221009A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=An%2C+Q">Q. An</a>, <a href="/search/?searchtype=author&query=Axikegu%2C+A">A. Axikegu</a>, <a href="/search/?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+Z">S. Z. Chen</a> , et al. (255 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="2310.08845v2-abstract-short" style="display: inline;"> The highest energy gamma-rays from gamma-ray bursts (GRBs) have important implications for their radiation mechanism. Here we report for the first time the detection of gamma-rays up to 13 TeV from the brightest GRB 221009A by the Large High Altitude Air-shower Observatory (LHAASO). The LHAASO-KM2A detector registered more than 140 gamma-rays with energies above 3 TeV during 230$-$900s after the t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.08845v2-abstract-full').style.display = 'inline'; document.getElementById('2310.08845v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.08845v2-abstract-full" style="display: none;"> The highest energy gamma-rays from gamma-ray bursts (GRBs) have important implications for their radiation mechanism. Here we report for the first time the detection of gamma-rays up to 13 TeV from the brightest GRB 221009A by the Large High Altitude Air-shower Observatory (LHAASO). The LHAASO-KM2A detector registered more than 140 gamma-rays with energies above 3 TeV during 230$-$900s after the trigger. The intrinsic energy spectrum of gamma-rays can be described by a power-law after correcting for extragalactic background light (EBL) absorption. Such a hard spectrum challenges the synchrotron self-Compton (SSC) scenario of relativistic electrons for the afterglow emission above several TeV. Observations of gamma-rays up to 13 TeV from a source with a measured redshift of z=0.151 hints more transparency in intergalactic space than previously expected. Alternatively, one may invoke new physics such as Lorentz Invariance Violation (LIV) or an axion origin of very high energy (VHE) signals. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.08845v2-abstract-full').style.display = 'none'; document.getElementById('2310.08845v2-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 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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">49pages, 11figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Science Advances, 9, eadj2778 (2023) 15 November 2023 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.06181">arXiv:2310.06181</a> <span> [<a href="https://arxiv.org/pdf/2310.06181">pdf</a>, <a href="https://arxiv.org/format/2310.06181">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/s41550-023-02052-3">10.1038/s41550-023-02052-3 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Discovery of a Radiation Component from the Vela Pulsar Reaching 20 Teraelectronvolts </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Collaboration%2C+T+H+E+S+S">The H. E. S. S. Collaboration</a>, <a href="/search/?searchtype=author&query=%3A"> :</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=Benkhali%2C+F+A">F. Ait Benkhali</a>, <a href="/search/?searchtype=author&query=Aschersleben%2C+J">J. Aschersleben</a>, <a href="/search/?searchtype=author&query=Ashkar%2C+H">H. Ashkar</a>, <a href="/search/?searchtype=author&query=Backes%2C+M">M. Backes</a>, <a href="/search/?searchtype=author&query=Martins%2C+V+B">V. Barbosa Martins</a>, <a href="/search/?searchtype=author&query=Batzofin%2C+R">R. Batzofin</a>, <a href="/search/?searchtype=author&query=Becherini%2C+Y">Y. Becherini</a>, <a href="/search/?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/?searchtype=author&query=Bernl%C3%B6hr%2C+K">K. Bernl枚hr</a>, <a href="/search/?searchtype=author&query=Bi%2C+B">B. Bi</a>, <a href="/search/?searchtype=author&query=B%C3%B6ttcher%2C+M">M. B枚ttcher</a>, <a href="/search/?searchtype=author&query=Boisson%2C+C">C. Boisson</a>, <a href="/search/?searchtype=author&query=Bolmont%2C+J">J. Bolmont</a>, <a href="/search/?searchtype=author&query=de+Lavergne%2C+M+d+B">M. de Bony de Lavergne</a>, <a href="/search/?searchtype=author&query=Borowska%2C+J">J. Borowska</a>, <a href="/search/?searchtype=author&query=Bradascio%2C+F">F. Bradascio</a>, <a href="/search/?searchtype=author&query=Breuhaus%2C+M">M. Breuhaus</a>, <a href="/search/?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/?searchtype=author&query=Brun%2C+F">F. Brun</a>, <a href="/search/?searchtype=author&query=Bruno%2C+B">B. Bruno</a>, <a href="/search/?searchtype=author&query=Bulik%2C+T">T. Bulik</a>, <a href="/search/?searchtype=author&query=Burger-Scheidlin%2C+C">C. Burger-Scheidlin</a> , et al. (157 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="2310.06181v1-abstract-short" style="display: inline;"> Gamma-ray observations have established energetic isolated pulsars as outstanding particle accelerators and antimatter factories in the Galaxy. There is, however, no consensus regarding the acceleration mechanisms and the radiative processes at play, nor the locations where these take place. The spectra of all observed gamma-ray pulsars to date show strong cutoffs or a break above energies of a fe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.06181v1-abstract-full').style.display = 'inline'; document.getElementById('2310.06181v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.06181v1-abstract-full" style="display: none;"> Gamma-ray observations have established energetic isolated pulsars as outstanding particle accelerators and antimatter factories in the Galaxy. There is, however, no consensus regarding the acceleration mechanisms and the radiative processes at play, nor the locations where these take place. The spectra of all observed gamma-ray pulsars to date show strong cutoffs or a break above energies of a few gigaelectronvolt (GeV). Using the H.E.S.S. array of Cherenkov telescopes, we discovered a novel radiation component emerging beyond this generic GeV cutoff in the Vela pulsar's broadband spectrum. The extension of gamma-ray pulsation energies up to at least 20 teraelectronvolts (TeV) shows that Vela pulsar can accelerate particles to Lorentz factors higher than $4\times10^7$. This is an order of magnitude larger than in the case of the Crab pulsar, the only other pulsar detected in the TeV energy range. Our results challenge the state-of-the-art models for high-energy emission of pulsars while providing a new probe, i.e. the energetic multi-TeV component, for constraining the acceleration and emission processes in their extreme energy limit. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.06181v1-abstract-full').style.display = 'none'; document.getElementById('2310.06181v1-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 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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">38 pages, 6 figures. This preprint has not undergone peer review or any post-submission improvements or corrections. The Version of Record of this article is published in Nature Astronomy, Nat Astron (2023), and is available online at https://doi.org/10.1038/s41550-023-02052-3</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2309.05426">arXiv:2309.05426</a> <span> [<a href="https://arxiv.org/pdf/2309.05426">pdf</a>, <a href="https://arxiv.org/format/2309.05426">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/stad2780">10.1093/mnras/stad2780 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Line profile of nuclear de-excitation gamma-ray emission from very hot plasma </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Yoneda%2C+H">Hiroki Yoneda</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">Felix Aharonian</a>, <a href="/search/?searchtype=author&query=Coppi%2C+P">Paolo Coppi</a>, <a href="/search/?searchtype=author&query=Siegert%2C+T">Thomas Siegert</a>, <a href="/search/?searchtype=author&query=Takahashi%2C+T">Tadayuki Takahashi</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="2309.05426v1-abstract-short" style="display: inline;"> De-excitation gamma-ray lines, produced by nuclei colliding with protons, provide information about astrophysical environments where particles have kinetic energies of $10-100$ MeV per nucleon. In general, such environments can be categorized into two types: the interaction between non-thermal MeV cosmic rays and ambient gas, and the other is thermal plasma with a temperature above a few MeV. In t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.05426v1-abstract-full').style.display = 'inline'; document.getElementById('2309.05426v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.05426v1-abstract-full" style="display: none;"> De-excitation gamma-ray lines, produced by nuclei colliding with protons, provide information about astrophysical environments where particles have kinetic energies of $10-100$ MeV per nucleon. In general, such environments can be categorized into two types: the interaction between non-thermal MeV cosmic rays and ambient gas, and the other is thermal plasma with a temperature above a few MeV. In this paper, we focus on the latter type and investigate the production of de-excitation gamma-ray lines in very hot thermal plasma, especially the dependence of the line profile on the plasma temperature. We have calculated the line profile of prompt gamma rays from $^{12}$C and $^{16}$O and found that when nuclei have a higher temperature than protons, gamma-ray line profiles can have a complex shape unique to each nucleus species. This is caused by anisotropic gamma-ray emission in the nucleus rest frame. We propose that the spectroscopy of nuclear de-excitation gamma-ray lines may enable to probe energy distribution in very hot astrophysical plasmas. This diagnostics can be a new and powerful technique to investigate the physical state of a two-temperature accretion flows onto a black hole, especially the energy distributions of the protons and nuclei, which are difficult to access for any other diagnostics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.05426v1-abstract-full').style.display = 'none'; document.getElementById('2309.05426v1-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> 11 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 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">12 pages, 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/2309.00673">arXiv:2309.00673</a> <span> [<a href="https://arxiv.org/pdf/2309.00673">pdf</a>, <a href="https://arxiv.org/format/2309.00673">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"> Naked forward shock seen in the TeV afterglow data of GRB221009A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Khangulyan%2C+D">Dmitry Khangulyan</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">Felix Aharonian</a>, <a href="/search/?searchtype=author&query=Taylor%2C+A+M">Andrew M. Taylor</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="2309.00673v1-abstract-short" style="display: inline;"> We explore the implications of the light curve of the early TeV gamma-ray afterglow of GRB221009A reported by the LHAASO collaboration. We show that the reported offset of the reference time, $T_*$, allows the determination of the relativistic jet activation time, which occurs approximately $200\,\mathrm{s}$ after the GBM trigger time and closely precedes the moment at which GBM was saturated. We… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.00673v1-abstract-full').style.display = 'inline'; document.getElementById('2309.00673v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.00673v1-abstract-full" style="display: none;"> We explore the implications of the light curve of the early TeV gamma-ray afterglow of GRB221009A reported by the LHAASO collaboration. We show that the reported offset of the reference time, $T_*$, allows the determination of the relativistic jet activation time, which occurs approximately $200\,\mathrm{s}$ after the GBM trigger time and closely precedes the moment at which GBM was saturated. We find that while the LHAASO data do not exclude the homogeneous circumburst medium scenario, the progenitor wind scenario looks preferable, finding excellent agreement with the expected size of the stellar bubble. We conclude that the initial growth of the light curve is dominated by processes internal to the jet or by gamma-gamma attenuation on the photons emitted during the prompt phase. Namely, either the activation of the acceleration process or the decrease of internal gamma-gamma absorption can naturally explain the initial rapid flux increase. The subsequent slow flux growth phase observed up to $T_*+18\,\mathrm{s}$ is explained by the build-up of the synchrotron radiation -- the target for inverse Compton scattering, which is also supported by a softer TeV spectrum measured during this period. The duration of this phase allows an almost parameter-independent determination of the jet's initial Lorentz factor, $螕_0\approx600$, and magnetic field strength, $B'\sim0.3\,\mathrm{G}$. These values appear to match well those previously revealed through spectral modeling of the GRB emission. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.00673v1-abstract-full').style.display = 'none'; document.getElementById('2309.00673v1-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 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 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, 6 figures, submitted</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.16685">arXiv:2308.16685</a> <span> [<a href="https://arxiv.org/pdf/2308.16685">pdf</a>, <a href="https://arxiv.org/format/2308.16685">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"> On the nature of the energy-dependent morphology of the composite multi-TeV gamma-ray source HESS J1702-420 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Aharonian%2C+F">Felix Aharonian</a>, <a href="/search/?searchtype=author&query=Malyshev%2C+D">Denys Malyshev</a>, <a href="/search/?searchtype=author&query=Chernyakova%2C+M">Maria Chernyakova</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="2308.16685v1-abstract-short" style="display: inline;"> HESS J1702-420 is a multi-TeV gamma-ray source with an unusual energy-dependent morphology. The recent H.E.S.S. observations suggest that the emission is well described by a combination of point-like HESS J1702-420A (dominating at highest energies, $\gtrsim$ 30 TeV ) and diffuse ($\sim$ 0.3$^\circ$) HESS J1702-420B (dominating below $\lesssim$ 5TeV) sources with very hard ($螕 \sim 1.5$) and soft (… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.16685v1-abstract-full').style.display = 'inline'; document.getElementById('2308.16685v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.16685v1-abstract-full" style="display: none;"> HESS J1702-420 is a multi-TeV gamma-ray source with an unusual energy-dependent morphology. The recent H.E.S.S. observations suggest that the emission is well described by a combination of point-like HESS J1702-420A (dominating at highest energies, $\gtrsim$ 30 TeV ) and diffuse ($\sim$ 0.3$^\circ$) HESS J1702-420B (dominating below $\lesssim$ 5TeV) sources with very hard ($螕 \sim 1.5$) and soft ($螕$ ~2.6) power-law spectra, respectively. Here we propose a model which postulates that the proton accelerator is located at the position of HESS J1702-420A and is embedded into a dense molecular cloud that coincides with HESS J1702-420B. In the proposed model, the VHE radiation of HESS J1702-420 is explained by the pion-decay emission from the continuously injected relativistic protons propagating through a dense cloud. The energy-dependent morphology is defined by the diffusive nature of the low-energy protons propagation, transiting sharply to (quasi) ballistic propagation at higher energies. Adopting strong energy dependence of the diffusion coefficient, $D \propto E^尾$ with $尾\geq 1$, we argue that HESS J1702-420 as the system of two gamma-ray sources is the result of the propagation effect. Protons injected by a single accelerator at the rate $Q_0 \simeq 10^{38} \, (n_0/100 \, \rm cm^{-3})^{-1}\, (d/ \, 0.25\,kpc)^{-1} \rm erg/s$ can reasonably reproduce the morphology and fluxes of two gamma-ray components. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.16685v1-abstract-full').style.display = 'none'; document.getElementById('2308.16685v1-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> 31 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 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">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/2307.12467">arXiv:2307.12467</a> <span> [<a href="https://arxiv.org/pdf/2307.12467">pdf</a>, <a href="https://arxiv.org/format/2307.12467">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"> On the properties of inverse Compton spectra generated by up-scattering a power-law distribution of target photons </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Khangulyan%2C+D">Dmitry Khangulyan</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">Felix Aharonian</a>, <a href="/search/?searchtype=author&query=Taylor%2C+A+M">Andrew M. Taylor</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="2307.12467v1-abstract-short" style="display: inline;"> Relativistic electrons are an essential component in many astrophysical sources, and their radiation may dominate the high-energy bands. Inverse Compton (IC) emission is the radiation mechanism that plays the most important role in these bands. The basic properties of IC, such as the total and differential cross sections, have long been studied; the properties of the IC emission depend strongly no… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.12467v1-abstract-full').style.display = 'inline'; document.getElementById('2307.12467v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.12467v1-abstract-full" style="display: none;"> Relativistic electrons are an essential component in many astrophysical sources, and their radiation may dominate the high-energy bands. Inverse Compton (IC) emission is the radiation mechanism that plays the most important role in these bands. The basic properties of IC, such as the total and differential cross sections, have long been studied; the properties of the IC emission depend strongly not only on the emitting electron distribution but also on the properties of the target photons. This complicates the phenomenological studies of sources, where target photons are supplied from a broad radiation component. We study the spectral properties of IC emission generated by a power-law distribution of electrons on a power-law distribution of target photons. We approximate the resulting spectrum by a broken-power-law distribution and show that there can be up to three physically motivated spectral breaks. If the target photon spectrum extends to sufficiently low energies, $\varepsilon_{\mathrm{min}}< m_e^2c^4/E_{\mathrm{max}}$ ($m_e$ and $c$ are electron mass and speed of light, respectively; $\varepsilon_{\mathrm{min}}$ and $E_{\mathrm{max}}$ are the minimum/maximum energies of target photons and electrons, respectively), then the high energy part of the IC component has a spectral slope typical for the Thomson regime with an abrupt cutoff close to $E_{\mathrm{max}}$. The spectra typical for the Klein-Nishina regime are formed above $m_e^2c^4/\varepsilon_{\mathrm{min}}$. If the spectrum of target photons features a cooling break, i.e., a change of the photon index by $0.5$ at $\varepsilon_{\mathrm{br}}$, then the transition to the Klein-Nishina regime proceeds through an intermediate change of the photon index by $0.5$ at $m_e^2c^4/\varepsilon_{\mathrm{br}}$. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.12467v1-abstract-full').style.display = 'none'; document.getElementById('2307.12467v1-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, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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">12 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/2307.08967">arXiv:2307.08967</a> <span> [<a href="https://arxiv.org/pdf/2307.08967">pdf</a>, <a href="https://arxiv.org/format/2307.08967">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="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Nuclear Experiment">nucl-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/10.1093/mnras/stad2165">10.1093/mnras/stad2165 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> New estimation of the nuclear de-excitation line emission from the supernova remnant Cassiopeia A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Liu%2C+B">Bing Liu</a>, <a href="/search/?searchtype=author&query=Yang%2C+R">Rui-zhi Yang</a>, <a href="/search/?searchtype=author&query=He%2C+X">Xin-yu He</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">Felix Aharonian</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="2307.08967v2-abstract-short" style="display: inline;"> MeV nuclear de-excitation lines serve as a unique tool to study low-energy cosmic rays (CRs), containing both spectral and elemental information of the interacting material. In this paper, we estimated the possible nuclear de-excitation lines from the young supernova remnant Cassiopeia A. Given different CR spectral shapes and interacting materials, we found the predicted fluxes of strong narrow l… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.08967v2-abstract-full').style.display = 'inline'; document.getElementById('2307.08967v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.08967v2-abstract-full" style="display: none;"> MeV nuclear de-excitation lines serve as a unique tool to study low-energy cosmic rays (CRs), containing both spectral and elemental information of the interacting material. In this paper, we estimated the possible nuclear de-excitation lines from the young supernova remnant Cassiopeia A. Given different CR spectral shapes and interacting materials, we found the predicted fluxes of strong narrow line emissions from the remnant are highly model-dependent, ranging from about $1\times10^{-10}\,{\rm \,cm^{-2}\,s^{-1}}$ to $1\times10^{-6}\, {\rm \,cm^{-2}\,s^{-1}}$ for the 4.44 MeV narrow line and from about $4\times10^{-11}\,{\rm \,cm^{-2}\,s^{-1}}$ to $2\times10^{-7}{\rm \,cm^{-2}\,s^{-1}}$ for the 6.13 MeV narrow line, respectively. Based on the new estimation, we also discussed the detection probability of these line emissions against the MeV diffuse Galactic background under different assumptions of instrument response functions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.08967v2-abstract-full').style.display = 'none'; document.getElementById('2307.08967v2-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 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 18 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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">6 pages, 6 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/2307.01692">arXiv:2307.01692</a> <span> [<a href="https://arxiv.org/pdf/2307.01692">pdf</a>, <a href="https://arxiv.org/format/2307.01692">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 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/ace3c0">10.3847/2041-8213/ace3c0 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The vanishing of the primary emission region in PKS 1510-089 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=Benkhali%2C+F+A">F. Ait Benkhali</a>, <a href="/search/?searchtype=author&query=Aschersleben%2C+J">J. Aschersleben</a>, <a href="/search/?searchtype=author&query=Ashkar%2C+H">H. Ashkar</a>, <a href="/search/?searchtype=author&query=Backes%2C+M">M. Backes</a>, <a href="/search/?searchtype=author&query=Martins%2C+V+B">V. Barbosa Martins</a>, <a href="/search/?searchtype=author&query=Barnard%2C+J">J. Barnard</a>, <a href="/search/?searchtype=author&query=Batzofin%2C+R">R. Batzofin</a>, <a href="/search/?searchtype=author&query=Becherini%2C+Y">Y. Becherini</a>, <a href="/search/?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/?searchtype=author&query=Bernloehr%2C+K">K. Bernloehr</a>, <a href="/search/?searchtype=author&query=Bi%2C+B">B. Bi</a>, <a href="/search/?searchtype=author&query=de+Lavergne%2C+M+d+B">M. de Bony de Lavergne</a>, <a href="/search/?searchtype=author&query=Boettcher%2C+M">M. Boettcher</a>, <a href="/search/?searchtype=author&query=Boisson%2C+C">C. Boisson</a>, <a href="/search/?searchtype=author&query=Bolmont%2C+J">J. Bolmont</a>, <a href="/search/?searchtype=author&query=Borowska%2C+J">J. Borowska</a>, <a href="/search/?searchtype=author&query=Bouyahiaoui%2C+M">M. Bouyahiaoui</a>, <a href="/search/?searchtype=author&query=Bradascio%2C+F">F. Bradascio</a>, <a href="/search/?searchtype=author&query=Breuhaus%2C+M">M. Breuhaus</a>, <a href="/search/?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/?searchtype=author&query=Brown%2C+A+M">A. M. Brown</a>, <a href="/search/?searchtype=author&query=Brun%2C+F">F. Brun</a>, <a href="/search/?searchtype=author&query=Bruno%2C+B">B. Bruno</a>, <a href="/search/?searchtype=author&query=Bulik%2C+T">T. Bulik</a> , et al. (130 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="2307.01692v1-abstract-short" style="display: inline;"> In July 2021, PKS 1510-089 exhibited a significant flux drop in the high-energy gamma-ray (by a factor 10) and optical (by a factor 5) bands and remained in this low state throughout 2022. Similarly, the optical polarization in the source vanished, resulting in the optical spectrum being fully explained through the steady flux of the accretion disk and the broad-line region. Unlike the aforementio… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.01692v1-abstract-full').style.display = 'inline'; document.getElementById('2307.01692v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.01692v1-abstract-full" style="display: none;"> In July 2021, PKS 1510-089 exhibited a significant flux drop in the high-energy gamma-ray (by a factor 10) and optical (by a factor 5) bands and remained in this low state throughout 2022. Similarly, the optical polarization in the source vanished, resulting in the optical spectrum being fully explained through the steady flux of the accretion disk and the broad-line region. Unlike the aforementioned bands, the very-high-energy gamma-ray and X-ray fluxes did not exhibit a significant flux drop from year to year. This suggests that the steady-state very-high-energy gamma-ray and X-ray fluxes originate from a different emission region than the vanished parts of the high-energy gamma-ray and optical jet fluxes. The latter component has disappeared through either a swing of the jet away from the line-of-sight or a significant drop in the photon production efficiency of the jet close to the black hole. Either change could become visible in high-resolution radio images. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.01692v1-abstract-full').style.display = 'none'; document.getElementById('2307.01692v1-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 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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, 4 figures, 6 tables; accepted for publication in ApJ Letters; corresponding authors: Joleen Barnard, Markus Boettcher, Hester Schutte, Michael Zacharias</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/?searchtype=author&query=Acharyya%2C+A">A. Acharyya</a>, <a href="/search/?searchtype=author&query=Adams%2C+C+B">C. B. Adams</a>, <a href="/search/?searchtype=author&query=Archer%2C+A">A. Archer</a>, <a href="/search/?searchtype=author&query=Bangale%2C+P">P. Bangale</a>, <a href="/search/?searchtype=author&query=Bartkoske%2C+J+T">J. T. Bartkoske</a>, <a href="/search/?searchtype=author&query=Batista%2C+P">P. Batista</a>, <a href="/search/?searchtype=author&query=Benbow%2C+W">W. Benbow</a>, <a href="/search/?searchtype=author&query=Brill%2C+A">A. Brill</a>, <a href="/search/?searchtype=author&query=Buckley%2C+J+H">J. H. Buckley</a>, <a href="/search/?searchtype=author&query=Christiansen%2C+J+L">J. L. Christiansen</a>, <a href="/search/?searchtype=author&query=Chromey%2C+A+J">A. J. Chromey</a>, <a href="/search/?searchtype=author&query=Errando%2C+M">M. Errando</a>, <a href="/search/?searchtype=author&query=Falcone%2C+A">A. Falcone</a>, <a href="/search/?searchtype=author&query=Feng%2C+Q">Q. Feng</a>, <a href="/search/?searchtype=author&query=Foote%2C+G+M">G. M. Foote</a>, <a href="/search/?searchtype=author&query=Fortson%2C+L">L. Fortson</a>, <a href="/search/?searchtype=author&query=Furniss%2C+A">A. Furniss</a>, <a href="/search/?searchtype=author&query=Gallagher%2C+G">G. Gallagher</a>, <a href="/search/?searchtype=author&query=Hanlon%2C+W">W. Hanlon</a>, <a href="/search/?searchtype=author&query=Hanna%2C+D">D. Hanna</a>, <a href="/search/?searchtype=author&query=Hervet%2C+O">O. Hervet</a>, <a href="/search/?searchtype=author&query=Hinrichs%2C+C+E">C. E. Hinrichs</a>, <a href="/search/?searchtype=author&query=Hoang%2C+J">J. Hoang</a>, <a href="/search/?searchtype=author&query=Holder%2C+J">J. Holder</a>, <a href="/search/?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/2306.05132">arXiv:2306.05132</a> <span> [<a href="https://arxiv.org/pdf/2306.05132">pdf</a>, <a href="https://arxiv.org/format/2306.05132">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/10.3847/2041-8213/acd777">10.3847/2041-8213/acd777 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Constraints on the intergalactic magnetic field using Fermi-LAT and H.E.S.S. blazar observations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=S.%2C+H+E+S">H. E. S. S.</a>, <a href="/search/?searchtype=author&query=Collaborations%2C+F">Fermi-LAT Collaborations</a>, <a href="/search/?searchtype=author&query=%3A"> :</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=Aschersleben%2C+J">J. Aschersleben</a>, <a href="/search/?searchtype=author&query=Backes%2C+M">M. Backes</a>, <a href="/search/?searchtype=author&query=Martins%2C+V+B">V. Barbosa Martins</a>, <a href="/search/?searchtype=author&query=Batzofin%2C+R">R. Batzofin</a>, <a href="/search/?searchtype=author&query=Becherini%2C+Y">Y. Becherini</a>, <a href="/search/?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/?searchtype=author&query=Bi%2C+B">B. Bi</a>, <a href="/search/?searchtype=author&query=Bouyahiaoui%2C+M">M. Bouyahiaoui</a>, <a href="/search/?searchtype=author&query=Breuhaus%2C+M">M. Breuhaus</a>, <a href="/search/?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/?searchtype=author&query=Brun%2C+F">F. Brun</a>, <a href="/search/?searchtype=author&query=Bruno%2C+B">B. Bruno</a>, <a href="/search/?searchtype=author&query=Bulik%2C+T">T. Bulik</a>, <a href="/search/?searchtype=author&query=Burger-Scheidlin%2C+C">C. Burger-Scheidlin</a>, <a href="/search/?searchtype=author&query=Bylund%2C+T">T. Bylund</a>, <a href="/search/?searchtype=author&query=Caroff%2C+S">S. Caroff</a>, <a href="/search/?searchtype=author&query=Casanova%2C+S">S. Casanova</a>, <a href="/search/?searchtype=author&query=Celic%2C+J">J. Celic</a>, <a href="/search/?searchtype=author&query=Cerruti%2C+M">M. Cerruti</a>, <a href="/search/?searchtype=author&query=Chand%2C+T">T. Chand</a>, <a href="/search/?searchtype=author&query=Chandra%2C+S">S. Chandra</a> , et al. (113 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="2306.05132v1-abstract-short" style="display: inline;"> Magnetic fields in galaxies and galaxy clusters are believed to be the result of the amplification of intergalactic seed fields during the formation of large-scale structures in the universe. However, the origin, strength, and morphology of this intergalactic magnetic field (IGMF) remain unknown. Lower limits on (or indirect detection of) the IGMF can be obtained from observations of high-energy g… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.05132v1-abstract-full').style.display = 'inline'; document.getElementById('2306.05132v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.05132v1-abstract-full" style="display: none;"> Magnetic fields in galaxies and galaxy clusters are believed to be the result of the amplification of intergalactic seed fields during the formation of large-scale structures in the universe. However, the origin, strength, and morphology of this intergalactic magnetic field (IGMF) remain unknown. Lower limits on (or indirect detection of) the IGMF can be obtained from observations of high-energy gamma rays from distant blazars. Gamma rays interact with the extragalactic background light to produce electron-positron pairs, which can subsequently initiate electromagnetic cascades. The $纬$-ray signature of the cascade depends on the IGMF since it deflects the pairs. Here we report on a new search for this cascade emission using a combined data set from the Fermi Large Area Telescope and the High Energy Stereoscopic System. Using state-of-the-art Monte Carlo predictions for the cascade signal, our results place a lower limit on the IGMF of $B > 7.1\times10^{-16}$ G for a coherence length of 1 Mpc even when blazar duty cycles as short as 10 yr are assumed. This improves on previous lower limits by a factor of 2. For longer duty cycles of $10^4$ ($10^7$) yr, IGMF strengths below $1.8\times10^{-14}$ G ($3.9\times10^{-14}$ G) are excluded, which rules out specific models for IGMF generation in the early universe. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.05132v1-abstract-full').style.display = 'none'; document.getElementById('2306.05132v1-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 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">20 pages, 7 figures, 4 tables. Accepted for publication in ApJ Letters. Auxiliary data is provided in electronic format at https://zenodo.org/record/8014311</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJ Letters 2023, Volume 950, Number 2 950, L16 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.17030">arXiv:2305.17030</a> <span> [<a href="https://arxiv.org/pdf/2305.17030">pdf</a>, <a href="https://arxiv.org/format/2305.17030">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 - Phenomenology">hep-ph</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/10.3847/1538-4365/acfd29">10.3847/1538-4365/acfd29 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The First LHAASO Catalog of Gamma-Ray Sources </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=An%2C+Q">Q. An</a>, <a href="/search/?searchtype=author&query=Axikegu"> Axikegu</a>, <a href="/search/?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+Z">S. Z. Chen</a> , et al. (255 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="2305.17030v2-abstract-short" style="display: inline;"> We present the first catalog of very-high energy and ultra-high energy gamma-ray sources detected by the Large High Altitude Air Shower Observatory (LHAASO). The catalog was compiled using 508 days of data collected by the Water Cherenkov Detector Array (WCDA) from March 2021 to September 2022 and 933 days of data recorded by the Kilometer Squared Array (KM2A) from January 2020 to September 2022.… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.17030v2-abstract-full').style.display = 'inline'; document.getElementById('2305.17030v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.17030v2-abstract-full" style="display: none;"> We present the first catalog of very-high energy and ultra-high energy gamma-ray sources detected by the Large High Altitude Air Shower Observatory (LHAASO). The catalog was compiled using 508 days of data collected by the Water Cherenkov Detector Array (WCDA) from March 2021 to September 2022 and 933 days of data recorded by the Kilometer Squared Array (KM2A) from January 2020 to September 2022. This catalog represents the main result from the most sensitive large coverage gamma-ray survey of the sky above 1 TeV, covering declination from $-$20$^{\circ}$ to 80$^{\circ}$. In total, the catalog contains 90 sources with an extended size smaller than $2^\circ$ and a significance of detection at $> 5蟽$. Based on our source association criteria, 32 new TeV sources are proposed in this study. Among the 90 sources, 43 sources are detected with ultra-high energy ($E > 100$ TeV) emission at $> 4蟽$ significance level. We provide the position, extension, and spectral characteristics of all the sources in this catalog. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.17030v2-abstract-full').style.display = 'none'; document.getElementById('2305.17030v2-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> 27 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 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">40 pages, 13 figures, 4 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> The Astrophysical Journal Supplement Series, 271 (2024) 25 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.09607">arXiv:2305.09607</a> <span> [<a href="https://arxiv.org/pdf/2305.09607">pdf</a>, <a href="https://arxiv.org/format/2305.09607">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 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/10.1051/0004-6361/202346056">10.1051/0004-6361/202346056 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Constraining the cosmic-ray pressure in the inner Virgo Cluster using H.E.S.S. observations of M 87 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Collaboration%2C+H+E+S+S">H. E. S. S. Collaboration</a>, <a href="/search/?searchtype=author&query=%3A"> :</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=Benkhali%2C+F+A">F. Ait Benkhali</a>, <a href="/search/?searchtype=author&query=Arcaro%2C+C">C. Arcaro</a>, <a href="/search/?searchtype=author&query=Aschersleben%2C+J">J. Aschersleben</a>, <a href="/search/?searchtype=author&query=Backes%2C+M">M. Backes</a>, <a href="/search/?searchtype=author&query=Martins%2C+V+B">V. Barbosa Martins</a>, <a href="/search/?searchtype=author&query=Batzofin%2C+R">R. Batzofin</a>, <a href="/search/?searchtype=author&query=Becherini%2C+Y">Y. Becherini</a>, <a href="/search/?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/?searchtype=author&query=Bernl%C3%B6hr%2C+K">K. Bernl枚hr</a>, <a href="/search/?searchtype=author&query=Bi%2C+B">B. Bi</a>, <a href="/search/?searchtype=author&query=B%C3%B6ttcher%2C+M">M. B枚ttcher</a>, <a href="/search/?searchtype=author&query=Boisson%2C+C">C. Boisson</a>, <a href="/search/?searchtype=author&query=Bolmont%2C+J">J. Bolmont</a>, <a href="/search/?searchtype=author&query=Borowska%2C+J">J. Borowska</a>, <a href="/search/?searchtype=author&query=Bradascio%2C+F">F. Bradascio</a>, <a href="/search/?searchtype=author&query=Breuhaus%2C+M">M. Breuhaus</a>, <a href="/search/?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/?searchtype=author&query=Brun%2C+F">F. Brun</a>, <a href="/search/?searchtype=author&query=Bruno%2C+B">B. Bruno</a>, <a href="/search/?searchtype=author&query=Bulik%2C+T">T. Bulik</a>, <a href="/search/?searchtype=author&query=Burger-Scheidlin%2C+C">C. Burger-Scheidlin</a>, <a href="/search/?searchtype=author&query=Bylund%2C+T">T. Bylund</a> , et al. (139 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="2305.09607v1-abstract-short" style="display: inline;"> The origin of the gamma-ray emission from M87 is currently a matter of debate. This work aims to localize the VHE (100 GeV-100 TeV) gamma-ray emission from M87 and probe a potential extended hadronic emission component in the inner Virgo Cluster. The search for a steady and extended gamma-ray signal around M87 can constrain the cosmic-ray energy density and the pressure exerted by the cosmic rays… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.09607v1-abstract-full').style.display = 'inline'; document.getElementById('2305.09607v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.09607v1-abstract-full" style="display: none;"> The origin of the gamma-ray emission from M87 is currently a matter of debate. This work aims to localize the VHE (100 GeV-100 TeV) gamma-ray emission from M87 and probe a potential extended hadronic emission component in the inner Virgo Cluster. The search for a steady and extended gamma-ray signal around M87 can constrain the cosmic-ray energy density and the pressure exerted by the cosmic rays onto the intra-cluster medium, and allow us to investigate the role of the cosmic rays in the active galactic nucleus feedback as a heating mechanism in the Virgo Cluster. H.E.S.S. telescopes are sensitive to VHE gamma rays and have been utilized to observe M87 since 2004. We utilized a Bayesian block analysis to identify M87 emission states with H.E.S.S. observations from 2004 until 2021, dividing them into low, intermediate, and high states. Because of the causality argument, an extended ($\gtrsim$kpc) signal is allowed only in steady emission states. Hence, we fitted the morphology of the 120h low state data and found no significant gamma-ray extension. Therefore, we derived for the low state an upper limit of 58"(corresponding to $\approx$4.6kpc) in the extension of a single-component morphological model described by a rotationally symmetric 2D Gaussian model at 99.7% confidence level. Our results exclude the radio lobes ($\approx$30 kpc) as the principal component of the VHE gamma-ray emission from the low state of M87. The gamma-ray emission is compatible with a single emission region at the radio core of M87. These results, with the help of two multiple-component models, constrain the maximum cosmic-ray to thermal pressure ratio $X_{CR,max.}$$\lesssim$$0.32$ and the total energy in cosmic-ray protons (CRp) to $U_{CR}$$\lesssim$5$\times10^{58}$ erg in the inner 20kpc of the Virgo Cluster for an assumed CRp power-law distribution in momentum with spectral index $伪_{p}$=2.1. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.09607v1-abstract-full').style.display = 'none'; document.getElementById('2305.09607v1-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> 16 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">15 pages, 7 figures. Accepted for publication in A&A. Corresponding authors: Victor Barbosa Martins, Stefan Ohm, Cornelia Arcaro, Natalia 呕ywucka, Mathieu de Naurois</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 675, A138 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.05372">arXiv:2305.05372</a> <span> [<a href="https://arxiv.org/pdf/2305.05372">pdf</a>, <a href="https://arxiv.org/format/2305.05372">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/10.1103/PhysRevLett.131.151001">10.1103/PhysRevLett.131.151001 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Measurement of ultra-high-energy diffuse gamma-ray emission of the Galactic plane from 10 TeV to 1 PeV with LHAASO-KM2A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=An%2C+Q">Q. An</a>, <a href="/search/?searchtype=author&query=Axikegu"> Axikegu</a>, <a href="/search/?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/?searchtype=author&query=Cao%2C+Q">Q. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+W+Y">W. Y. Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/?searchtype=author&query=Chen%2C+A+M">A. M. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+Q+H">Q. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+Z">S. Z. Chen</a> , et al. (255 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="2305.05372v2-abstract-short" style="display: inline;"> The diffuse Galactic $纬$-ray emission, mainly produced via interactions between cosmic rays and the interstellar medium and/or radiation field, is a very important probe of the distribution, propagation, and interaction of cosmic rays in the Milky Way. In this work we report the measurements of diffuse $纬$-rays from the Galactic plane between 10 TeV and 1 PeV energies, with the square kilometer ar… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.05372v2-abstract-full').style.display = 'inline'; document.getElementById('2305.05372v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.05372v2-abstract-full" style="display: none;"> The diffuse Galactic $纬$-ray emission, mainly produced via interactions between cosmic rays and the interstellar medium and/or radiation field, is a very important probe of the distribution, propagation, and interaction of cosmic rays in the Milky Way. In this work we report the measurements of diffuse $纬$-rays from the Galactic plane between 10 TeV and 1 PeV energies, with the square kilometer array of the Large High Altitude Air Shower Observatory (LHAASO). Diffuse emissions from the inner ($15^{\circ}<l<125^{\circ}$, $|b|<5^{\circ}$) and outer ($125^{\circ}<l<235^{\circ}$, $|b|<5^{\circ}$) Galactic plane are detected with $29.1蟽$ and $12.7蟽$ significance, respectively. The outer Galactic plane diffuse emission is detected for the first time in the very- to ultra-high-energy domain ($E>10$~TeV). The energy spectrum in the inner Galaxy regions can be described by a power-law function with an index of $-2.99\pm0.04$, which is different from the curved spectrum as expected from hadronic interactions between locally measured cosmic rays and the line-of-sight integrated gas content. Furthermore, the measured flux is higher by a factor of $\sim3$ than the prediction. A similar spectrum with an index of $-2.99\pm0.07$ is found in the outer Galaxy region, and the absolute flux for $10\lesssim E\lesssim60$ TeV is again higher than the prediction for hadronic cosmic ray interactions. The latitude distributions of the diffuse emission are consistent with the gas distribution, while the longitude distributions show clear deviation from the gas distribution. The LHAASO measurements imply that either additional emission sources exist or cosmic ray intensities have spatial variations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.05372v2-abstract-full').style.display = 'none'; document.getElementById('2305.05372v2-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> 19 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 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">12 pages, 8 figures, 5 tables; accepted for publication in Physical Review Letters; source mask file provided as ancillary file</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 131, 151001 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.02631">arXiv:2304.02631</a> <span> [<a href="https://arxiv.org/pdf/2304.02631">pdf</a>, <a href="https://arxiv.org/format/2304.02631">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/10.1051/0004-6361/202245776">10.1051/0004-6361/202245776 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Detection of extended gamma-ray emission around the Geminga pulsar with H.E.S.S </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Collaboration%2C+H+E+S+S">H. E. S. S. Collaboration</a>, <a href="/search/?searchtype=author&query=%3A"> :</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=Benkhali%2C+F+A">F. Ait Benkhali</a>, <a href="/search/?searchtype=author&query=Aschersleben%2C+J">J. Aschersleben</a>, <a href="/search/?searchtype=author&query=Ashkar%2C+H">H. Ashkar</a>, <a href="/search/?searchtype=author&query=Backes%2C+M">M. Backes</a>, <a href="/search/?searchtype=author&query=Martins%2C+V+B">V. Barbosa Martins</a>, <a href="/search/?searchtype=author&query=Batzofin%2C+R">R. Batzofin</a>, <a href="/search/?searchtype=author&query=Becherini%2C+Y">Y. Becherini</a>, <a href="/search/?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/?searchtype=author&query=Bernl%C3%B6hr%2C+K">K. Bernl枚hr</a>, <a href="/search/?searchtype=author&query=Bi%2C+B">B. Bi</a>, <a href="/search/?searchtype=author&query=B%C3%B6ttcher%2C+M">M. B枚ttcher</a>, <a href="/search/?searchtype=author&query=Boisson%2C+C">C. Boisson</a>, <a href="/search/?searchtype=author&query=Bolmont%2C+J">J. Bolmont</a>, <a href="/search/?searchtype=author&query=Borowska%2C+J">J. Borowska</a>, <a href="/search/?searchtype=author&query=Bouyahiaoui%2C+M">M. Bouyahiaoui</a>, <a href="/search/?searchtype=author&query=Bradascio%2C+F">F. Bradascio</a>, <a href="/search/?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/?searchtype=author&query=Brun%2C+F">F. Brun</a>, <a href="/search/?searchtype=author&query=Bruno%2C+B">B. Bruno</a>, <a href="/search/?searchtype=author&query=Bulik%2C+T">T. Bulik</a>, <a href="/search/?searchtype=author&query=Scheidlin%2C+C+B">C. Burger Scheidlin</a>, <a href="/search/?searchtype=author&query=Cangemi%2C+F">F. Cangemi</a> , et al. (143 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="2304.02631v1-abstract-short" style="display: inline;"> Geminga is an enigmatic radio-quiet gamma-ray pulsar located at a mere 250 pc distance from Earth. Extended very-high-energy gamma-ray emission around the pulsar was discovered by Milagro and later confirmed by HAWC, which are both water Cherenkov detector-based experiments. However, evidence for the Geminga pulsar wind nebula in gamma rays has long evaded detection by imaging atmospheric Cherenko… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.02631v1-abstract-full').style.display = 'inline'; document.getElementById('2304.02631v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.02631v1-abstract-full" style="display: none;"> Geminga is an enigmatic radio-quiet gamma-ray pulsar located at a mere 250 pc distance from Earth. Extended very-high-energy gamma-ray emission around the pulsar was discovered by Milagro and later confirmed by HAWC, which are both water Cherenkov detector-based experiments. However, evidence for the Geminga pulsar wind nebula in gamma rays has long evaded detection by imaging atmospheric Cherenkov telescopes (IACTs) despite targeted observations. The detection of gamma-ray emission on angular scales > 2 deg poses a considerable challenge for the background estimation in IACT data analysis. With recent developments in understanding the complementary background estimation techniques of water Cherenkov and atmospheric Cherenkov instruments, the H.E.S.S. IACT array can now confirm the detection of highly extended gamma-ray emission around the Geminga pulsar with a radius of at least 3 deg in the energy range 0.5-40 TeV. We find no indications for statistically significant asymmetries or energy-dependent morphology. A flux normalisation of $(2.8\pm0.7)\times10^{-12}$ cm$^{-2}$s$^{-1}$TeV$^{-1}$ at 1 TeV is obtained within a 1 deg radius region around the pulsar. To investigate the particle transport within the halo of energetic leptons around the pulsar, we fitted an electron diffusion model to the data. The normalisation of the diffusion coefficient obtained of $D_0 = 7.6^{+1.5}_{-1.2} \times 10^{27}$ cm$^2$s$^{-1}$, at an electron energy of 100 TeV, is compatible with values previously reported for the pulsar halo around Geminga, which is considerably below the Galactic average. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.02631v1-abstract-full').style.display = 'none'; document.getElementById('2304.02631v1-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> 5 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">16 pages, 15 figures, 7 tables. Accepted for publication in Astronomy & Astrophysics</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 673, A148 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.12855">arXiv:2303.12855</a> <span> [<a href="https://arxiv.org/pdf/2303.12855">pdf</a>, <a href="https://arxiv.org/format/2303.12855">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/10.1088/1475-7516/2023/04/040">10.1088/1475-7516/2023/04/040 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Search for the evaporation of primordial black holes with H.E.S.S </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=collaboration%2C+H+E+S+S">H. E. S. S. collaboration</a>, <a href="/search/?searchtype=author&query=%3A"> :</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=Benkhali%2C+F+A">F. Ait Benkhali</a>, <a href="/search/?searchtype=author&query=Aschersleben%2C+J">J. Aschersleben</a>, <a href="/search/?searchtype=author&query=Boettcher%2C+M">M. Boettcher</a>, <a href="/search/?searchtype=author&query=Backes%2C+M">M. Backes</a>, <a href="/search/?searchtype=author&query=Martins%2C+V+B">V. Barbosa Martins</a>, <a href="/search/?searchtype=author&query=Batzo%2C+R">R. Batzo</a>, <a href="/search/?searchtype=author&query=Becherini%2C+Y">Y. Becherini</a>, <a href="/search/?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/?searchtype=author&query=Bi%2C+B">B. Bi</a>, <a href="/search/?searchtype=author&query=Boisson%2C+C">C. Boisson</a>, <a href="/search/?searchtype=author&query=Bolmont%2C+J">J. Bolmont</a>, <a href="/search/?searchtype=author&query=de+Lavergne%2C+M+d+B">M. de Bony de Lavergne</a>, <a href="/search/?searchtype=author&query=Borowska%2C+J">J. Borowska</a>, <a href="/search/?searchtype=author&query=Bradascio%2C+F">F. Bradascio</a>, <a href="/search/?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/?searchtype=author&query=Brun%2C+F">F. Brun</a>, <a href="/search/?searchtype=author&query=Bruno%2C+B">B. Bruno</a>, <a href="/search/?searchtype=author&query=Bulik%2C+T">T. Bulik</a>, <a href="/search/?searchtype=author&query=Burger-Scheidlin%2C+C">C. Burger-Scheidlin</a>, <a href="/search/?searchtype=author&query=Caro%2C+S">S. Caro</a>, <a href="/search/?searchtype=author&query=Casanova%2C+S">S. Casanova</a>, <a href="/search/?searchtype=author&query=Celic%2C+J">J. Celic</a> , et al. (124 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="2303.12855v1-abstract-short" style="display: inline;"> Primordial Black Holes (PBHs) are hypothetical black holes predicted to have been formed from density fluctuations in the early Universe. PBHs with an initial mass around $10^{14}-10^{15}$g are expected to end their evaporation at present times in a burst of particles and very-high-energy (VHE) gamma rays. Those gamma rays may be detectable by the High Energy Stereoscopic System (H.E.S.S.), an arr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.12855v1-abstract-full').style.display = 'inline'; document.getElementById('2303.12855v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.12855v1-abstract-full" style="display: none;"> Primordial Black Holes (PBHs) are hypothetical black holes predicted to have been formed from density fluctuations in the early Universe. PBHs with an initial mass around $10^{14}-10^{15}$g are expected to end their evaporation at present times in a burst of particles and very-high-energy (VHE) gamma rays. Those gamma rays may be detectable by the High Energy Stereoscopic System (H.E.S.S.), an array of imaging atmospheric Cherenkov telescopes. This paper reports on the search for evaporation bursts of VHE gamma rays with H.E.S.S., ranging from 10 to 120 seconds, as expected from the final stage of PBH evaporation and using a total of 4816 hours of observations. The most constraining upper limit on the burst rate of local PBHs is $2000$ pc$^{-3}$ yr$^{-1}$ for a burst interval of 120 seconds, at the 95\% confidence level. The implication of these measurements for PBH dark matter are also discussed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.12855v1-abstract-full').style.display = 'none'; document.getElementById('2303.12855v1-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 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 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">Accepted for publication in JCAP, corresponding authors: F.Brun, J-F. Glicenstein, V. Marandon, T. Tavernier</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.10558">arXiv:2303.10558</a> <span> [<a href="https://arxiv.org/pdf/2303.10558">pdf</a>, <a href="https://arxiv.org/format/2303.10558">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/acc405">10.3847/2041-8213/acc405 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> H.E.S.S. follow-up observations of GRB221009A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Collaboration%2C+H+E+S+S">H. E. S. S. Collaboration</a>, <a href="/search/?searchtype=author&query=%3A"> :</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=Benkhali%2C+F+A">F. Ait Benkhali</a>, <a href="/search/?searchtype=author&query=Aschersleben%2C+J">J. Aschersleben</a>, <a href="/search/?searchtype=author&query=Ashkar%2C+H">H. Ashkar</a>, <a href="/search/?searchtype=author&query=Backes%2C+M">M. Backes</a>, <a href="/search/?searchtype=author&query=Baktash%2C+A">A. Baktash</a>, <a href="/search/?searchtype=author&query=Martins%2C+V+B">V. Barbosa Martins</a>, <a href="/search/?searchtype=author&query=Batzofin%2C+R">R. Batzofin</a>, <a href="/search/?searchtype=author&query=Becherini%2C+Y">Y. Becherini</a>, <a href="/search/?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/?searchtype=author&query=Bernl%C3%B6hr%2C+K">K. Bernl枚hr</a>, <a href="/search/?searchtype=author&query=Bi%2C+B">B. Bi</a>, <a href="/search/?searchtype=author&query=B%C3%B6ttcher%2C+M">M. B枚ttcher</a>, <a href="/search/?searchtype=author&query=Boisson%2C+C">C. Boisson</a>, <a href="/search/?searchtype=author&query=Bolmont%2C+J">J. Bolmont</a>, <a href="/search/?searchtype=author&query=de+Lavergne%2C+M+d+B">M. de Bony de Lavergne</a>, <a href="/search/?searchtype=author&query=Borowska%2C+J">J. Borowska</a>, <a href="/search/?searchtype=author&query=Bouyahiaoui%2C+M">M. Bouyahiaoui</a>, <a href="/search/?searchtype=author&query=Bradascio%2C+F">F. Bradascio</a>, <a href="/search/?searchtype=author&query=Breuhaus%2C+M">M. Breuhaus</a>, <a href="/search/?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/?searchtype=author&query=Brun%2C+F">F. Brun</a>, <a href="/search/?searchtype=author&query=Bruno%2C+B">B. Bruno</a> , et al. (138 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="2303.10558v1-abstract-short" style="display: inline;"> GRB221009A is the brightest gamma-ray burst ever detected. To probe the very-high-energy (VHE, $>$\!100 GeV) emission, the High Energy Stereoscopic System (H.E.S.S.) began observations 53 hours after the triggering event, when the brightness of the moonlight no longer precluded observations. We derive differential and integral upper limits using H.E.S.S. data from the third, fourth, and ninth nigh… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.10558v1-abstract-full').style.display = 'inline'; document.getElementById('2303.10558v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.10558v1-abstract-full" style="display: none;"> GRB221009A is the brightest gamma-ray burst ever detected. To probe the very-high-energy (VHE, $>$\!100 GeV) emission, the High Energy Stereoscopic System (H.E.S.S.) began observations 53 hours after the triggering event, when the brightness of the moonlight no longer precluded observations. We derive differential and integral upper limits using H.E.S.S. data from the third, fourth, and ninth nights after the initial GRB detection, after applying atmospheric corrections. The combined observations yield an integral energy flux upper limit of $桅_\mathrm{UL}^{95\%} = 9.7 \times 10^{-12}~\mathrm{erg\,cm^{-2}\,s^{-1}}$ above $E_\mathrm{thr} = 650$ GeV. The constraints derived from the H.E.S.S. observations complement the available multiwavelength data. The radio to X-ray data are consistent with synchrotron emission from a single electron population, with the peak in the SED occurring above the X-ray band. Compared to the VHE-bright GRB190829A, the upper limits for GRB221009A imply a smaller gamma-ray to X-ray flux ratio in the afterglow. Even in the absence of a detection, the H.E.S.S. upper limits thus contribute to the multiwavelength picture of GRB221009A, effectively ruling out an IC dominated scenario. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.10558v1-abstract-full').style.display = 'none'; document.getElementById('2303.10558v1-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 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 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">10 pages, 4 figures. Accepted for publication in APJL. Corresponding authors: J. Damascene Mbarubucyeye, H. Ashkar, S. J. Zhu, B. Reville, F. Sch眉ssler</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.13663">arXiv:2302.13663</a> <span> [<a href="https://arxiv.org/pdf/2302.13663">pdf</a>, <a href="https://arxiv.org/format/2302.13663">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/10.1051/0004-6361/202245459">10.1051/0004-6361/202245459 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> HESS J1809$-$193: a halo of escaped electrons around a pulsar wind nebula? </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Collaboration%2C+H+E+S+S">H. E. S. S. Collaboration</a>, <a href="/search/?searchtype=author&query=%3A"> :</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=Benkhali%2C+F+A">F. Ait Benkhali</a>, <a href="/search/?searchtype=author&query=Aschersleben%2C+J">J. Aschersleben</a>, <a href="/search/?searchtype=author&query=Ashkar%2C+H">H. Ashkar</a>, <a href="/search/?searchtype=author&query=Backes%2C+M">M. Backes</a>, <a href="/search/?searchtype=author&query=Martins%2C+V+B">V. Barbosa Martins</a>, <a href="/search/?searchtype=author&query=Batzofin%2C+R">R. Batzofin</a>, <a href="/search/?searchtype=author&query=Becherini%2C+Y">Y. Becherini</a>, <a href="/search/?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/?searchtype=author&query=B%C3%B6ttcher%2C+M">M. B枚ttcher</a>, <a href="/search/?searchtype=author&query=Boisson%2C+C">C. Boisson</a>, <a href="/search/?searchtype=author&query=Bolmont%2C+J">J. Bolmont</a>, <a href="/search/?searchtype=author&query=Borowska%2C+J">J. Borowska</a>, <a href="/search/?searchtype=author&query=Bouyahiaoui%2C+M">M. Bouyahiaoui</a>, <a href="/search/?searchtype=author&query=Bradascio%2C+F">F. Bradascio</a>, <a href="/search/?searchtype=author&query=Breuhaus%2C+M">M. Breuhaus</a>, <a href="/search/?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/?searchtype=author&query=Brun%2C+F">F. Brun</a>, <a href="/search/?searchtype=author&query=Bruno%2C+B">B. Bruno</a>, <a href="/search/?searchtype=author&query=Bulik%2C+T">T. Bulik</a>, <a href="/search/?searchtype=author&query=Burger-Scheidlin%2C+C">C. Burger-Scheidlin</a>, <a href="/search/?searchtype=author&query=Bylund%2C+T">T. Bylund</a>, <a href="/search/?searchtype=author&query=Caroff%2C+S">S. Caroff</a> , et al. (130 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="2302.13663v1-abstract-short" style="display: inline;"> Context. HESS J1809$-$193 is an unassociated very-high-energy $纬$-ray source located on the Galactic plane. While it has been connected to the nebula of the energetic pulsar PSR J1809$-$1917, supernova remnants and molecular clouds present in the vicinity also constitute possible associations. Recently, the detection of $纬$-ray emission up to energies of $\sim$100 TeV with the HAWC observatory has… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.13663v1-abstract-full').style.display = 'inline'; document.getElementById('2302.13663v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.13663v1-abstract-full" style="display: none;"> Context. HESS J1809$-$193 is an unassociated very-high-energy $纬$-ray source located on the Galactic plane. While it has been connected to the nebula of the energetic pulsar PSR J1809$-$1917, supernova remnants and molecular clouds present in the vicinity also constitute possible associations. Recently, the detection of $纬$-ray emission up to energies of $\sim$100 TeV with the HAWC observatory has led to renewed interest in HESS J1809$-$193. Aims. We aim to understand the origin of the $纬$-ray emission of HESS J1809$-$193. Methods. We analysed 93.2 h of data taken on HESS J1809$-$193 above 0.27 TeV with the High Energy Stereoscopic System (H.E.S.S.), using a multi-component, three-dimensional likelihood analysis. In addition, we provide a new analysis of 12.5 yr of Fermi-LAT data above 1 GeV within the region of HESS J1809$-$193. The obtained results are interpreted in a time-dependent modelling framework. Results. For the first time, we were able to resolve the emission detected with H.E.S.S. into two components: an extended component that exhibits a spectral cut-off at $\sim$13 TeV, and a compact component that is located close to PSR J1809$-$1917 and shows no clear spectral cut-off. The Fermi-LAT analysis also revealed extended $纬$-ray emission, on scales similar to that of the extended H.E.S.S. component. Conclusions. Our modelling indicates that based on its spectrum and spatial extent, the extended H.E.S.S. component is likely caused by inverse Compton emission from old electrons that form a halo around the pulsar wind nebula. The compact component could be connected to either the pulsar wind nebula or the supernova remnant and molecular clouds. Due to its comparatively steep spectrum, modelling the Fermi-LAT emission together with the H.E.S.S. components is not straightforward. (abridged) <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.13663v1-abstract-full').style.display = 'none'; document.getElementById('2302.13663v1-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> 27 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">14 pages, 10 figures. Accepted for publication in A&A. Corresponding authors: Vikas Joshi, Lars Mohrmann</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 672, A103 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2301.08578">arXiv:2301.08578</a> <span> [<a href="https://arxiv.org/pdf/2301.08578">pdf</a>, <a href="https://arxiv.org/format/2301.08578">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/acc24e">10.3847/1538-4357/acc24e <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The formation of hard VHE spectra from GRB afterglow via Two-Zone Synchrotron Self-Compton Emission </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Khangulyan%2C+D">Dmitry Khangulyan</a>, <a href="/search/?searchtype=author&query=Taylor%2C+A+M">Andrew M. Taylor</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">Felix Aharonian</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="2301.08578v1-abstract-short" style="display: inline;"> Electron Compton scattering of target photons into the gamma-ray energy band (inverse Compton scattering --IC--) is commonly expected to dominate the very high energy spectra in gamma-ray bursts especially during the afterglow phase. For sufficiently large center-of-mass energies in these collisions, the effect of the electron recoil starts reducing the scattering cross section (the Klein-Nishina… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2301.08578v1-abstract-full').style.display = 'inline'; document.getElementById('2301.08578v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2301.08578v1-abstract-full" style="display: none;"> Electron Compton scattering of target photons into the gamma-ray energy band (inverse Compton scattering --IC--) is commonly expected to dominate the very high energy spectra in gamma-ray bursts especially during the afterglow phase. For sufficiently large center-of-mass energies in these collisions, the effect of the electron recoil starts reducing the scattering cross section (the Klein-Nishina regime). The IC spectra generated in the Klein-Nishina regime is softer and has a smaller flux level compared to the synchrotron spectra produced by the same electrons. The detection of afterglow emission from nearby GRB 190819A in the very high energy (VHE) domain with H.E.S.S. has revealed an unexpected feature: the slope of the VHE spectrum matches well the slope of the X-ray spectra, despite expectations that for the IC production process, the impact of the Klein-Nishina effect should be strong. The multi-wavelength spectral energy distribution appears to be inconsistent with predictions of one-zone synchrotron-self-Compton models. We study the possible impact of two-zone configuration on the properties of IC emission when the magnetic field strength differs considerably between the two zones. Synchrotron photons from the strong magnetic field zone provide the dominant target for cooling of the electrons in the weak magnetic field zone, which results in a formation of hard electron distribution and consequently of a hard IC emission. We show that the two-zone model can provide a good description of the X-ray XRT and VHE H.E.S.S. data. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2301.08578v1-abstract-full').style.display = 'none'; document.getElementById('2301.08578v1-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 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">13 pages, 7 figures, ApJ submitted</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2301.06716">arXiv:2301.06716</a> <span> [<a href="https://arxiv.org/pdf/2301.06716">pdf</a>, <a href="https://arxiv.org/format/2301.06716">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/s41550-022-01868-9">10.1038/s41550-022-01868-9 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Effective Shielding of $\lesssim$ 10 GeV Cosmic Rays from Dense Molecular Clumps </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Yang%2C+R">Rui-zhi Yang</a>, <a href="/search/?searchtype=author&query=Li%2C+G">Guang-Xing Li</a>, <a href="/search/?searchtype=author&query=Wilhelmi%2C+E+d+O">Emma de O帽a Wilhelmi</a>, <a href="/search/?searchtype=author&query=Cui%2C+Y">Yu-Dong Cui</a>, <a href="/search/?searchtype=author&query=Liu%2C+B">Bing Liu</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">Felix Aharonian</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="2301.06716v1-abstract-short" style="display: inline;"> The density of cosmic rays inside molecular clouds determines the ionization rate in the dense cores where stars form. It is also one of the drivers of astrochemistry leading to the creation of complex molecules. Through Fermi Large Area Telescope observations of nearby giant molecular clouds, we observed deficits (holes) in the gamma-ray residual map when modelling with the expected gamma-ray dif… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2301.06716v1-abstract-full').style.display = 'inline'; document.getElementById('2301.06716v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2301.06716v1-abstract-full" style="display: none;"> The density of cosmic rays inside molecular clouds determines the ionization rate in the dense cores where stars form. It is also one of the drivers of astrochemistry leading to the creation of complex molecules. Through Fermi Large Area Telescope observations of nearby giant molecular clouds, we observed deficits (holes) in the gamma-ray residual map when modelling with the expected gamma-ray diffuse emission from uniform cosmic rays interacting with the molecular content. We propose that the deficit is due to the lack of penetration of the low-energy (sub-GeV to GeV) cosmic rays into denser regions or clumps. This differs from the prevailing view of fast cosmic ray transport in giant molecular clouds where the magnetic turbulence is suppressed by neutral-ion damping, as our results require a slow diffusion inside dense molecular clumps. Through modelling we find that while the shielding is negligible on the cloud scale, it becomes important in the denser, parsec-sized regions where the gravitational collapse is already at play, changing the initial condition of star formation and astrochemistry. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2301.06716v1-abstract-full').style.display = 'none'; document.getElementById('2301.06716v1-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> 17 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">Published in Nature Astronomy</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nat Astron (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.14007">arXiv:2212.14007</a> <span> [<a href="https://arxiv.org/pdf/2212.14007">pdf</a>, <a href="https://arxiv.org/format/2212.14007">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/10.1051/0004-6361/202345850">10.1051/0004-6361/202345850 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Pre-merger alert to detect the very-high-energy prompt emission from binary neutron-star mergers: Einstein Telescope and Cherenkov Telescope Array synergy </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Banerjee%2C+B">Biswajit Banerjee</a>, <a href="/search/?searchtype=author&query=Oganesyan%2C+G">Gor Oganesyan</a>, <a href="/search/?searchtype=author&query=Branchesi%2C+M">Marica Branchesi</a>, <a href="/search/?searchtype=author&query=Dupletsa%2C+U">Ulyana Dupletsa</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">Felix Aharonian</a>, <a href="/search/?searchtype=author&query=Brighenti%2C+F">Francesco Brighenti</a>, <a href="/search/?searchtype=author&query=Goncharov%2C+B">Boris Goncharov</a>, <a href="/search/?searchtype=author&query=Harms%2C+J">Jan Harms</a>, <a href="/search/?searchtype=author&query=Mapelli%2C+M">Michela Mapelli</a>, <a href="/search/?searchtype=author&query=Ronchini%2C+S">Samuele Ronchini</a>, <a href="/search/?searchtype=author&query=Santoliquido%2C+F">Filippo Santoliquido</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="2212.14007v2-abstract-short" style="display: inline;"> The current generation of very-high-energy $gamma-$ray (VHE; E above 30 GeV) detectors (MAGIC and H.E.S.S.) have recently demonstrated the ability to detect the afterglow emission of GRBs. However, the GRB prompt emission, typically observed in the 10 keV-10 MeV band, has so far remained undetected at higher energies. Here, we investigate the perspectives of multi-messenger observations to detect… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.14007v2-abstract-full').style.display = 'inline'; document.getElementById('2212.14007v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.14007v2-abstract-full" style="display: none;"> The current generation of very-high-energy $gamma-$ray (VHE; E above 30 GeV) detectors (MAGIC and H.E.S.S.) have recently demonstrated the ability to detect the afterglow emission of GRBs. However, the GRB prompt emission, typically observed in the 10 keV-10 MeV band, has so far remained undetected at higher energies. Here, we investigate the perspectives of multi-messenger observations to detect the prompt emission of short GRBs in VHE. Considering binary neutron star mergers as progenitors of short GRBs, we evaluate the joint detection efficiency of the Cherenkov Telescope Array (CTA) observing in synergy with the third generation of gravitational wave detectors, such as the Einstein Telescope (ET) and Cosmic Explorer (CE). In particular, we evaluate the expected capabilities to detect and localize gravitational wave events in the inspiral phase and to provide an early warning alert able to drive the VHE search. We compute the amount of possible joint detections by considering several observational strategies, and demonstrate that the sensitivities of CTA make the detection of the VHE emission possible even if it is several orders fainter than the one observed at 10 keV-10 MeV. We discuss the results in terms of possible scenarios of production of VHE photons from binary neutron star mergers by considering GRB prompt and afterglow emissions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.14007v2-abstract-full').style.display = 'none'; document.getElementById('2212.14007v2-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 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 28 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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 publication in Astronomy and Astrophysics</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 678, A126 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.03226">arXiv:2212.03226</a> <span> [<a href="https://arxiv.org/pdf/2212.03226">pdf</a>, <a href="https://arxiv.org/format/2212.03226">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/stac3616">10.1093/mnras/stac3616 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Particle acceleration in shearing flows: the self-generation of turbulent spine-sheath structures in relativistic MHD jet simulations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Wang%2C+J">Jie-Shuang Wang</a>, <a href="/search/?searchtype=author&query=Reville%2C+B">Brian Reville</a>, <a href="/search/?searchtype=author&query=Mizuno%2C+Y">Yosuke Mizuno</a>, <a href="/search/?searchtype=author&query=Rieger%2C+F+M">Frank M. Rieger</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F+A">Felix A. Aharonian</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="2212.03226v1-abstract-short" style="display: inline;"> X-ray observations of several kiloparsec-scale extragalactic jets favour a synchrotron origin. The short cooling times of the emitting electrons requires distributed acceleration of electrons up to sub-PeV energies. In a previous paper, we found that this can be self-consistently explained by a shear acceleration model, where particles are accelerated to produce power-law spectra with a spectral i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.03226v1-abstract-full').style.display = 'inline'; document.getElementById('2212.03226v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.03226v1-abstract-full" style="display: none;"> X-ray observations of several kiloparsec-scale extragalactic jets favour a synchrotron origin. The short cooling times of the emitting electrons requires distributed acceleration of electrons up to sub-PeV energies. In a previous paper, we found that this can be self-consistently explained by a shear acceleration model, where particles are accelerated to produce power-law spectra with a spectral index being determined mainly by the velocity profile and turbulence spectrum. In this paper, we perform 3D relativistic magneto-hydrodynamic simulations to investigate the formation of a spine-sheath structure and the development of turbulence for a relativistic jet propagating into a static cocoon. We explore different spine velocities and magnetic field profiles with values being chosen to match typical Fanaroff-Riley type I/II jets. We find that in all cases a sheath is generated on the interface of the spine and the cocoon mainly due to the Kelvin-Helmholtz instability. The large scale velocity profile in the sheath is close to linear. Turbulence develops in both the spine and the sheath, with a turbulent velocity spectrum consistent with Kolmogorov-scaling. The implications for shear particle acceleration are explored, with a focus on the particle spectral index. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.03226v1-abstract-full').style.display = 'none'; document.getElementById('2212.03226v1-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 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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">9 pages, 11 figures, 1 table, 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/2209.09785">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/?searchtype=author&query=Abe%2C+H">H. Abe</a>, <a href="/search/?searchtype=author&query=Abe%2C+S">S. Abe</a>, <a href="/search/?searchtype=author&query=Acciari%2C+V+A">V. A. Acciari</a>, <a href="/search/?searchtype=author&query=Aniello%2C+T">T. Aniello</a>, <a href="/search/?searchtype=author&query=Ansoldi%2C+S">S. Ansoldi</a>, <a href="/search/?searchtype=author&query=Antonelli%2C+L+A">L. A. Antonelli</a>, <a href="/search/?searchtype=author&query=Engels%2C+A+A">A. Arbet Engels</a>, <a href="/search/?searchtype=author&query=Arcaro%2C+C">C. Arcaro</a>, <a href="/search/?searchtype=author&query=Artero%2C+M">M. Artero</a>, <a href="/search/?searchtype=author&query=Asano%2C+K">K. Asano</a>, <a href="/search/?searchtype=author&query=Baack%2C+D">D. Baack</a>, <a href="/search/?searchtype=author&query=Babi%C4%87%2C+A">A. Babi膰</a>, <a href="/search/?searchtype=author&query=Baquero%2C+A">A. Baquero</a>, <a href="/search/?searchtype=author&query=de+Almeida%2C+U+B">U. Barres de Almeida</a>, <a href="/search/?searchtype=author&query=Barrio%2C+J+A">J. A. Barrio</a>, <a href="/search/?searchtype=author&query=Batkovi%C4%87%2C+I">I. Batkovi膰</a>, <a href="/search/?searchtype=author&query=Baxter%2C+J">J. Baxter</a>, <a href="/search/?searchtype=author&query=Gonz%C3%A1lez%2C+J+B">J. Becerra Gonz谩lez</a>, <a href="/search/?searchtype=author&query=Bednarek%2C+W">W. Bednarek</a>, <a href="/search/?searchtype=author&query=Bernardini%2C+E">E. Bernardini</a>, <a href="/search/?searchtype=author&query=Bernardos%2C+M">M. Bernardos</a>, <a href="/search/?searchtype=author&query=Berti%2C+A">A. Berti</a>, <a href="/search/?searchtype=author&query=Besenrieder%2C+J">J. Besenrieder</a>, <a href="/search/?searchtype=author&query=Bhattacharyya%2C+W">W. Bhattacharyya</a>, <a href="/search/?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/2207.12601">arXiv:2207.12601</a> <span> [<a href="https://arxiv.org/pdf/2207.12601">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> <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/10.1088/1674-1137/ac9371">10.1088/1674-1137/ac9371 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Flux Variations of Cosmic Ray Air Showers Detected by LHAASO-KM2A During a Thunderstorm on 10 June 2021 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=LHAASO+Collaboration"> LHAASO Collaboration</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=An%2C+Q">Q. An</a>, <a href="/search/?searchtype=author&query=Axikegu"> Axikegu</a>, <a href="/search/?searchtype=author&query=Bai%2C+L+X">L. X. Bai</a>, <a href="/search/?searchtype=author&query=Bai%2C+Y+X">Y. X. Bai</a>, <a href="/search/?searchtype=author&query=Bao%2C+Y+W">Y. W. Bao</a>, <a href="/search/?searchtype=author&query=Bastieri%2C+D">D. Bastieri</a>, <a href="/search/?searchtype=author&query=Bi%2C+X+J">X. J. Bi</a>, <a href="/search/?searchtype=author&query=Bi%2C+Y+J">Y. J. Bi</a>, <a href="/search/?searchtype=author&query=Cai%2C+J+T">J. T. Cai</a>, <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhe Cao</a>, <a href="/search/?searchtype=author&query=Cao%2C+Z">Zhen Cao</a>, <a href="/search/?searchtype=author&query=Chang%2C+J">J. Chang</a>, <a href="/search/?searchtype=author&query=Chang%2C+J+F">J. F. Chang</a>, <a href="/search/?searchtype=author&query=Chen%2C+E+S">E. S. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+L">Long Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+J">M. J. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+M+L">M. L. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+H">S. H. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+S+Z">S. Z. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+T+L">T. L. Chen</a>, <a href="/search/?searchtype=author&query=Chen%2C+X+J">X. J. Chen</a> , et al. (248 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="2207.12601v2-abstract-short" style="display: inline;"> The Large High Altitude Air Shower Observatory (LHAASO) has three sub-arrays, KM2A, WCDA and WFCTA. The flux variations of cosmic ray air showers were studied by analyzing the KM2A data during the thunderstorm on 10 June 2021. The number of shower events that meet the trigger conditions increases significantly in atmospheric electric fields, with maximum fractional increase of 20%. The variations… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.12601v2-abstract-full').style.display = 'inline'; document.getElementById('2207.12601v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.12601v2-abstract-full" style="display: none;"> The Large High Altitude Air Shower Observatory (LHAASO) has three sub-arrays, KM2A, WCDA and WFCTA. The flux variations of cosmic ray air showers were studied by analyzing the KM2A data during the thunderstorm on 10 June 2021. The number of shower events that meet the trigger conditions increases significantly in atmospheric electric fields, with maximum fractional increase of 20%. The variations of trigger rates (increases or decreases) are found to be strongly dependent on the primary zenith angle. The flux of secondary particles increases significantly, following a similar trend with that of the shower events. To better understand the observed behavior, Monte Carlo simulations are performed with CORSIKA and G4KM2A (a code based on GEANT4). We find that the experimental data (in saturated negative fields) are in good agreement with simulations, assuming the presence of a uniform upward electric field of 700 V/cm with a thickness of 1500 m in the atmosphere above the observation level. Due to the acceleration/deceleration and deflection by the atmospheric electric field, the number of secondary particles with energy above the detector threshold is modified, resulting in the changes in shower detection rate. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.12601v2-abstract-full').style.display = 'none'; document.getElementById('2207.12601v2-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 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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">18 pages, 11 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Chinese Phys. C 47 015001 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2207.10921">arXiv:2207.10921</a> <span> [<a href="https://arxiv.org/pdf/2207.10921">pdf</a>, <a href="https://arxiv.org/format/2207.10921">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/10.1051/0004-6361/202244323">10.1051/0004-6361/202244323 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A deep spectromorphological study of the $纬$-ray emission surrounding the young massive stellar cluster Westerlund 1 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=Ashkar%2C+H">H. Ashkar</a>, <a href="/search/?searchtype=author&query=Backes%2C+M">M. Backes</a>, <a href="/search/?searchtype=author&query=Martins%2C+V+B">V. Barbosa Martins</a>, <a href="/search/?searchtype=author&query=Becherini%2C+Y">Y. Becherini</a>, <a href="/search/?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/?searchtype=author&query=Bi%2C+B">B. Bi</a>, <a href="/search/?searchtype=author&query=B%C3%B6ttcher%2C+M">M. B枚ttcher</a>, <a href="/search/?searchtype=author&query=de+Lavergne%2C+M+d+B">M. de Bony de Lavergne</a>, <a href="/search/?searchtype=author&query=Bradascio%2C+F">F. Bradascio</a>, <a href="/search/?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/?searchtype=author&query=Brun%2C+F">F. Brun</a>, <a href="/search/?searchtype=author&query=Bulik%2C+T">T. Bulik</a>, <a href="/search/?searchtype=author&query=Burger-Scheidlin%2C+C">C. Burger-Scheidlin</a>, <a href="/search/?searchtype=author&query=Cangemi%2C+F">F. Cangemi</a>, <a href="/search/?searchtype=author&query=Caroff%2C+S">S. Caroff</a>, <a href="/search/?searchtype=author&query=Casanova%2C+S">S. Casanova</a>, <a href="/search/?searchtype=author&query=Cerruti%2C+M">M. Cerruti</a>, <a href="/search/?searchtype=author&query=Chand%2C+T">T. Chand</a>, <a href="/search/?searchtype=author&query=Chandra%2C+S">S. Chandra</a>, <a href="/search/?searchtype=author&query=Chen%2C+A">A. Chen</a>, <a href="/search/?searchtype=author&query=Chibueze%2C+O">O. Chibueze</a>, <a href="/search/?searchtype=author&query=Cristofari%2C+P">P. Cristofari</a>, <a href="/search/?searchtype=author&query=Mbarubucyeye%2C+J+D">J. Damascene Mbarubucyeye</a>, <a href="/search/?searchtype=author&query=Djannati-Ata%C3%AF%2C+A">A. Djannati-Ata茂</a> , et al. (134 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="2207.10921v2-abstract-short" style="display: inline;"> Young massive stellar clusters are extreme environments and potentially provide the means for efficient particle acceleration. Indeed, they are increasingly considered as being responsible for a significant fraction of cosmic rays (CRs) accelerated within the Milky Way. Westerlund 1, the most massive known young stellar cluster in our Galaxy is a prime candidate for studying this hypothesis. While… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.10921v2-abstract-full').style.display = 'inline'; document.getElementById('2207.10921v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.10921v2-abstract-full" style="display: none;"> Young massive stellar clusters are extreme environments and potentially provide the means for efficient particle acceleration. Indeed, they are increasingly considered as being responsible for a significant fraction of cosmic rays (CRs) accelerated within the Milky Way. Westerlund 1, the most massive known young stellar cluster in our Galaxy is a prime candidate for studying this hypothesis. While the very-high-energy $纬$-ray source HESS J1646-458 has been detected in the vicinity of Westerlund 1 in the past, its association could not be firmly identified. We aim to identify the physical processes responsible for the $纬$-ray emission around Westerlund 1 and thus to better understand the role of massive stellar clusters in the acceleration of Galactic CRs. Using 164 hours of data recorded with the High Energy Stereoscopic System (H.E.S.S.), we carried out a deep spectromorphological study of the $纬$-ray emission of HESS J1646-458. We furthermore employed H I and CO observations of the region to infer the presence of gas that could serve as target material for interactions of accelerated CRs. We detected large-scale ($\sim 2^\circ$ diameter) $纬$-ray emission with a complex morphology, exhibiting a shell-like structure and showing no significant variation with $纬$-ray energy. The combined energy spectrum of the emission extends to several tens of TeV, and is uniform across the entire source region. We did not find a clear correlation of the $纬$-ray emission with gas clouds as identified through H I and CO observations. We conclude that, of the known objects within the region, only Westerlund 1 can explain the bulk of the $纬$-ray emission. Several CR acceleration sites and mechanisms are conceivable, and discussed in detail. (abridged) <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.10921v2-abstract-full').style.display = 'none'; document.getElementById('2207.10921v2-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 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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, 9 figures. Corresponding authors: L. Mohrmann, S. Ohm, R. Rauth, A. Specovius. v2: corrected affiliation of M. Vecchi (still incorrect in journal version)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 666, A124 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2207.10471">arXiv:2207.10471</a> <span> [<a href="https://arxiv.org/pdf/2207.10471">pdf</a>, <a href="https://arxiv.org/format/2207.10471">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/10.1103/PhysRevLett.129.111101">10.1103/PhysRevLett.129.111101 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Search for dark matter annihilation signals in the H.E.S.S. Inner Galaxy Survey </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Collaboration%2C+H+E+S+S">H. E. S. S. Collaboration</a>, <a href="/search/?searchtype=author&query=Abdalla%2C+H">H. Abdalla</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/?searchtype=author&query=Benkhali%2C+F+A">F. Ait Benkhali</a>, <a href="/search/?searchtype=author&query=Anguner%2C+E+O">E. O. Anguner</a>, <a href="/search/?searchtype=author&query=Armand%2C+C">C. Armand</a>, <a href="/search/?searchtype=author&query=Ashkar%2C+H">H. Ashkar</a>, <a href="/search/?searchtype=author&query=Backes%2C+M">M. Backes</a>, <a href="/search/?searchtype=author&query=Baghmanyan%2C+V">V. Baghmanyan</a>, <a href="/search/?searchtype=author&query=Martins%2C+V+B">V. Barbosa Martins</a>, <a href="/search/?searchtype=author&query=Batzofin%2C+R">R. Batzofin</a>, <a href="/search/?searchtype=author&query=Becherini%2C+Y">Y. Becherini</a>, <a href="/search/?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/?searchtype=author&query=Bernlohr%2C+K">K. Bernlohr</a>, <a href="/search/?searchtype=author&query=Bi%2C+B">B. Bi</a>, <a href="/search/?searchtype=author&query=Bottcher%2C+M">M. Bottcher</a>, <a href="/search/?searchtype=author&query=Bolmont%2C+J">J. Bolmont</a>, <a href="/search/?searchtype=author&query=de+Lavergne%2C+M+d+B">M. de Bony de Lavergne</a>, <a href="/search/?searchtype=author&query=Brose%2C+R">R. Brose</a>, <a href="/search/?searchtype=author&query=Brun%2C+F">F. Brun</a>, <a href="/search/?searchtype=author&query=Cangemi%2C+F">F. Cangemi</a>, <a href="/search/?searchtype=author&query=Caroff%2C+S">S. Caroff</a>, <a href="/search/?searchtype=author&query=Cerruti%2C+M">M. Cerruti</a>, <a href="/search/?searchtype=author&query=Chand%2C+T">T. Chand</a>, <a href="/search/?searchtype=author&query=Chen%2C+A">A. Chen</a> , et al. (116 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="2207.10471v1-abstract-short" style="display: inline;"> The central region of the Milky Way is one of the foremost locations to look for dark matter (DM) signatures. We report the first results on a search for DM particle annihilation signals using new observations from an unprecedented gamma-ray survey of the Galactic Center (GC) region, ${\it i.e.}$, the Inner Galaxy Survey, at very high energies ($\gtrsim$ 100 GeV) performed with the H.E.S.S. array… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.10471v1-abstract-full').style.display = 'inline'; document.getElementById('2207.10471v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.10471v1-abstract-full" style="display: none;"> The central region of the Milky Way is one of the foremost locations to look for dark matter (DM) signatures. We report the first results on a search for DM particle annihilation signals using new observations from an unprecedented gamma-ray survey of the Galactic Center (GC) region, ${\it i.e.}$, the Inner Galaxy Survey, at very high energies ($\gtrsim$ 100 GeV) performed with the H.E.S.S. array of five ground-based Cherenkov telescopes. No significant gamma-ray excess is found in the search region of the 2014-2020 dataset and a profile likelihood ratio analysis is carried out to set exclusion limits on the annihilation cross section $\langle 蟽v\rangle$. Assuming Einasto and Navarro-Frenk-White (NFW) DM density profiles at the GC, these constraints are the strongest obtained so far in the TeV DM mass range. For the Einasto profile, the constraints reach $\langle 蟽v\rangle$ values of $\rm 3.7\times10^{-26} cm^3s^{-1}$ for 1.5 TeV DM mass in the $W^+W^-$ annihilation channel, and $\rm 1.2 \times 10^{-26} cm^3s^{-1}$ for 0.7 TeV DM mass in the $蟿^+蟿^-$ annihilation channel. With the H.E.S.S. Inner Galaxy Survey, ground-based $纬$-ray observations thus probe $\langle 蟽v\rangle$ values expected from thermal-relic annihilating TeV DM particles. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.10471v1-abstract-full').style.display = 'none'; document.getElementById('2207.10471v1-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> 21 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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 in Phys. Rev. Lett., includes Supplemental materials. 5+10 pages, 2+8 figures, 4 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 129, 111101 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2207.01432">arXiv:2207.01432</a> <span> [<a href="https://arxiv.org/pdf/2207.01432">pdf</a>, <a href="https://arxiv.org/format/2207.01432">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/stac1901">10.1093/mnras/stac1901 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Can superbubbles accelerate ultra-high energy protons? </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Vieu%2C+T">Thibault Vieu</a>, <a href="/search/?searchtype=author&query=Reville%2C+B">Brian Reville</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">Felix Aharonian</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="2207.01432v1-abstract-short" style="display: inline;"> We critically assess limits on the maximum energy of protons accelerated within superbubbles around massive stellar clusters, considering a number of different scenarios. In particular, we derive under which circumstances acceleration of protons above peta-electronvolt (PeV) energies can be expected. While the external forward shock of the superbubble may account for acceleration of particles up t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.01432v1-abstract-full').style.display = 'inline'; document.getElementById('2207.01432v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.01432v1-abstract-full" style="display: none;"> We critically assess limits on the maximum energy of protons accelerated within superbubbles around massive stellar clusters, considering a number of different scenarios. In particular, we derive under which circumstances acceleration of protons above peta-electronvolt (PeV) energies can be expected. While the external forward shock of the superbubble may account for acceleration of particles up to 100 TeV, internal primary shocks such as supernova remnants expanding in the low density medium or the collective wind termination shock which forms around a young compact cluster provide more favourable channels to accelerate protons up to 1 PeV, and possibly beyond. Under reasonable conditions, clustered supernovae launching powerful shocks into the magnetised wind of a young and compact massive star cluster are found to be the most promising systems to accelerate protons above 10 PeV. On the other hand, stochastic re-acceleration in the strongly turbulent plasma is found to be much less effective than claimed in previous works, with a maximum proton energy of at most a few hundred TeV. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.01432v1-abstract-full').style.display = 'none'; document.getElementById('2207.01432v1-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 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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">10 pages, 5 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/2207.00573">arXiv:2207.00573</a> <span> [<a href="https://arxiv.org/pdf/2207.00573">pdf</a>, <a href="https://arxiv.org/format/2207.00573">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/ac7c05">10.3847/1538-4357/ac7c05 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Hard X-ray emission from the eastern jet of SS 433 powering the W50 `Manatee' nebula: Evidence for particle re-acceleration </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Safi-Harb%2C+S">Samar Safi-Harb</a>, <a href="/search/?searchtype=author&query=Mac+Intyre%2C+B">Brydyn Mac Intyre</a>, <a href="/search/?searchtype=author&query=Zhang%2C+S">Shuo Zhang</a>, <a href="/search/?searchtype=author&query=Pope%2C+I">Isaac Pope</a>, <a href="/search/?searchtype=author&query=Zhang%2C+S">Shuhan Zhang</a>, <a href="/search/?searchtype=author&query=Saffold%2C+N">Nathan Saffold</a>, <a href="/search/?searchtype=author&query=Mori%2C+K">Kaya Mori</a>, <a href="/search/?searchtype=author&query=Gotthelf%2C+E+V">Eric V. Gotthelf</a>, <a href="/search/?searchtype=author&query=Aharonian%2C+F">Felix Aharonian</a>, <a href="/search/?searchtype=author&query=Band%2C+M">Matthew Band</a>, <a href="/search/?searchtype=author&query=Braun%2C+C">Chelsea Braun</a>, <a href="/search/?searchtype=author&query=Fang%2C+K">Ke Fang</a>, <a href="/search/?searchtype=author&query=Hailey%2C+C">Charles Hailey</a>, <a href="/search/?searchtype=author&query=Nynka%2C+M">Melania Nynka</a>, <a href="/search/?searchtype=author&query=Rho%2C+C+D">Chang D. Rho</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="2207.00573v1-abstract-short" style="display: inline;"> We present a broadband X-ray study of W50 (`the Manatee nebula'), the complex region powered by the microquasar SS 433, that provides a test-bed for several important astrophysical processes. The W50 nebula, a Galactic PeVatron candidate, is classified as a supernova remnant but has an unusual double-lobed morphology likely associated with the jets from SS 433. Using NuSTAR, XMM-Newton, and Chandr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.00573v1-abstract-full').style.display = 'inline'; document.getElementById('2207.00573v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.00573v1-abstract-full" style="display: none;"> We present a broadband X-ray study of W50 (`the Manatee nebula'), the complex region powered by the microquasar SS 433, that provides a test-bed for several important astrophysical processes. The W50 nebula, a Galactic PeVatron candidate, is classified as a supernova remnant but has an unusual double-lobed morphology likely associated with the jets from SS 433. Using NuSTAR, XMM-Newton, and Chandra observations of the inner eastern lobe of W50, we have detected hard non-thermal X-ray emission up to $\sim$30 keV, originating from a few-arcminute size knotty region (`Head') located $\lesssim$ 18$^{\prime}$ (29 pc for a distance of 5.5 kpc) east of SS 433, and constrain its photon index to 1.58$\pm$0.05 (0.5-30 keV band). The index gradually steepens eastward out to the radio `ear' where thermal soft X-ray emission with a temperature $kT$$\sim$0.2 keV dominates. The hard X-ray knots mark the location of acceleration sites within the jet and require an equipartition magnetic field of the order of $\gtrsim$12$渭$G. The unusually hard spectral index from the `Head' region challenges classical particle acceleration processes and points to particle injection and re-acceleration in the sub-relativistic SS 433 jet, as seen in blazars and pulsar wind nebulae. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.00573v1-abstract-full').style.display = 'none'; document.getElementById('2207.00573v1-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 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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, 9 figures, 2 tables, accepted for publication in the Astrophysical Journal</span> </p> </li> </ol> <nav class="pagination is-small is-centered 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