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href="/search/?searchtype=author&query=van+der+Horst%2C+A+J&start=150" class="pagination-link " aria-label="Page 4" aria-current="page">4 </a> </li> <li> <a href="/search/?searchtype=author&query=van+der+Horst%2C+A+J&start=200" class="pagination-link " aria-label="Page 5" aria-current="page">5 </a> </li> </ul> </nav> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2412.09732">arXiv:2412.09732</a> <span> [<a href="https://arxiv.org/pdf/2412.09732">pdf</a>, <a href="https://arxiv.org/format/2412.09732">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> </div> </div> <p class="title is-5 mathjax"> Revisiting the Intergalactic Medium Around GRB 130606A and Constraints on the Epoch of Reionization </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Fausey%2C+H+M">H. M. Fausey</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Tanvir%2C+N+R">N. R. Tanvir</a>, <a href="/search/astro-ph?searchtype=author&query=Wiersema%2C+K">K. Wiersema</a>, <a href="/search/astro-ph?searchtype=author&query=Fynbo%2C+J+P+U">J. P. U. Fynbo</a>, <a href="/search/astro-ph?searchtype=author&query=Hartmann%2C+D">D. Hartmann</a>, <a href="/search/astro-ph?searchtype=author&query=Postigo%2C+A+d+U">A. de Ugarte Postigo</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="2412.09732v1-abstract-short" style="display: inline;"> Gamma-ray bursts (GRBs) are excellent probes of the high-redshift Universe due to their high luminosities and the relatively simple intrinsic spectra of their afterglows. They can be used to estimate the fraction of neutral hydrogen (i.e., neutral fraction) in the intergalactic medium at different redshifts through the examination of their Lyman-alpha damping wing with high quality optical-to-near… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.09732v1-abstract-full').style.display = 'inline'; document.getElementById('2412.09732v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.09732v1-abstract-full" style="display: none;"> Gamma-ray bursts (GRBs) are excellent probes of the high-redshift Universe due to their high luminosities and the relatively simple intrinsic spectra of their afterglows. They can be used to estimate the fraction of neutral hydrogen (i.e., neutral fraction) in the intergalactic medium at different redshifts through the examination of their Lyman-alpha damping wing with high quality optical-to-near-infrared spectra. Neutral fraction estimates can help trace the evolution of the Epoch of Reionization, a key era of cosmological history in which the intergalactic medium underwent a phase change from neutral to ionized. We revisit GRB 130606A, a z ~ 5.9 GRB for which multiple analyses, using the same damping wing model and data from different telescopes, found conflicting neutral fraction results. We identify the source of the discrepant results to be differences in assumptions for key damping wing model parameters and data range selections. We perform a new analysis implementing multiple GRB damping wing models and find a 3-sigma neutral fraction upper limit ranging from xHI < 0.20 to xHI < 0.23. We present this result in the context of other neutral fraction estimates and Epoch of Reionization models, discuss the impact of relying on individual GRB lines of sight, and highlight the need for more high-redshift GRBs to effectively constrain the progression of the Epoch of Reionization. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.09732v1-abstract-full').style.display = 'none'; document.getElementById('2412.09732v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages, 11 figures, submitted 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/2412.02832">arXiv:2412.02832</a> <span> [<a href="https://arxiv.org/pdf/2412.02832">pdf</a>, <a href="https://arxiv.org/format/2412.02832">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> </div> <p class="title is-5 mathjax"> Commensal Transient Searches with MeerKAT in Gamma-Ray Burst and Supernova Fields </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Chastain%2C+S+I">S. I. Chastain</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Horesh%2C+A">A. Horesh</a>, <a href="/search/astro-ph?searchtype=author&query=Rowlinson%2C+A">A. Rowlinson</a>, <a href="/search/astro-ph?searchtype=author&query=Andersson%2C+A">A. Andersson</a>, <a href="/search/astro-ph?searchtype=author&query=Diretse%2C+R">R. Diretse</a>, <a href="/search/astro-ph?searchtype=author&query=Vaccari%2C+M">M. Vaccari</a>, <a href="/search/astro-ph?searchtype=author&query=Fender%2C+R+P">R. P. Fender</a>, <a href="/search/astro-ph?searchtype=author&query=Woudt%2C+P+A">P. A. Woudt</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="2412.02832v2-abstract-short" style="display: inline;"> The sensitivity and field of view of the MeerKAT radio telescope provides excellent opportunities for commensal transient searches. We carry out a commensal transient search in supernova and short gamma-ray burst fields using methodologies established in Chastain et al. (2023). We search for transients in MeerKAT L-band images with 30 minute integration times, finding 13 variable sources. We compa… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.02832v2-abstract-full').style.display = 'inline'; document.getElementById('2412.02832v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.02832v2-abstract-full" style="display: none;"> The sensitivity and field of view of the MeerKAT radio telescope provides excellent opportunities for commensal transient searches. We carry out a commensal transient search in supernova and short gamma-ray burst fields using methodologies established in Chastain et al. (2023). We search for transients in MeerKAT L-band images with 30 minute integration times, finding 13 variable sources. We compare these sources to the VLASS and RACS survey data, and examine possible explanation for the variability. We find that 12 of these sources are consistent with variability due to interstellar scintillation. The remaining source could possibly have some intrinsic variability. We also split the MeerKAT L-band into an upper and lower half, and search for transients in images with an 8 second integration time. We find a source with a duration of 8 to 16 seconds that is highly polarized at the lowest frequencies. We conclude that this source may be consistent with a stellar flare. Finally, we calculate accurate upper and lower limits on the transient rate using transient simulations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.02832v2-abstract-full').style.display = 'none'; document.getElementById('2412.02832v2-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 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">submitted to 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/2409.19056">arXiv:2409.19056</a> <span> [<a href="https://arxiv.org/pdf/2409.19056">pdf</a>, <a href="https://arxiv.org/format/2409.19056">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 Einstein Probe transient EP240414a: Linking Fast X-ray Transients, Gamma-ray Bursts and Luminous Fast Blue Optical Transients </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=van+Dalen%2C+J+N+D">Joyce N. D. van Dalen</a>, <a href="/search/astro-ph?searchtype=author&query=Levan%2C+A+J">Andrew J. Levan</a>, <a href="/search/astro-ph?searchtype=author&query=Jonker%2C+P+G">Peter G. Jonker</a>, <a href="/search/astro-ph?searchtype=author&query=Malesani%2C+D+B">Daniele B. Malesani</a>, <a href="/search/astro-ph?searchtype=author&query=Izzo%2C+L">Luca Izzo</a>, <a href="/search/astro-ph?searchtype=author&query=Sarin%2C+N">Nikhil Sarin</a>, <a href="/search/astro-ph?searchtype=author&query=Quirola-V%C3%A1squez%2C+J">Jonathan Quirola-V谩squez</a>, <a href="/search/astro-ph?searchtype=author&query=S%C3%A1nchez%2C+D+M">Daniel Mata S谩nchez</a>, <a href="/search/astro-ph?searchtype=author&query=Postigo%2C+A+d+U">Antonio de Ugarte Postigo</a>, <a href="/search/astro-ph?searchtype=author&query=van+Hoof%2C+A+P+C">Agnes P. C. van Hoof</a>, <a href="/search/astro-ph?searchtype=author&query=Torres%2C+M+A+P">Manuel A. P. Torres</a>, <a href="/search/astro-ph?searchtype=author&query=Schulze%2C+S">Steve Schulze</a>, <a href="/search/astro-ph?searchtype=author&query=Littlefair%2C+S+P">Stuart P. Littlefair</a>, <a href="/search/astro-ph?searchtype=author&query=Chrimes%2C+A">Ashley Chrimes</a>, <a href="/search/astro-ph?searchtype=author&query=Ravasio%2C+M+E">Maria E. Ravasio</a>, <a href="/search/astro-ph?searchtype=author&query=Bauer%2C+F+E">Franz E. Bauer</a>, <a href="/search/astro-ph?searchtype=author&query=Martin-Carrillo%2C+A">Antonio Martin-Carrillo</a>, <a href="/search/astro-ph?searchtype=author&query=Fraser%2C+M">Morgan Fraser</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">Alexander J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Jakobsson%2C+P">Pall Jakobsson</a>, <a href="/search/astro-ph?searchtype=author&query=O%27Brien%2C+P">Paul O'Brien</a>, <a href="/search/astro-ph?searchtype=author&query=De+Pasquale%2C+M">Massimiliano De Pasquale</a>, <a href="/search/astro-ph?searchtype=author&query=Pugliese%2C+G">Giovanna Pugliese</a>, <a href="/search/astro-ph?searchtype=author&query=Sollerman%2C+J">Jesper Sollerman</a>, <a href="/search/astro-ph?searchtype=author&query=Tanvir%2C+N+R">Nial R. Tanvir</a> , et al. (8 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2409.19056v1-abstract-short" style="display: inline;"> Detections of fast X-ray transients (FXTs) have been accrued over the last few decades. However, their origin has remained mysterious. There is now rapid progress thanks to timely discoveries and localisations with the Einstein Probe mission. Early results indicate that FXTs may frequently, but not always, be associated with gamma-ray bursts (GRBs). Here, we report on the multi-wavelength counterp… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.19056v1-abstract-full').style.display = 'inline'; document.getElementById('2409.19056v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.19056v1-abstract-full" style="display: none;"> Detections of fast X-ray transients (FXTs) have been accrued over the last few decades. However, their origin has remained mysterious. There is now rapid progress thanks to timely discoveries and localisations with the Einstein Probe mission. Early results indicate that FXTs may frequently, but not always, be associated with gamma-ray bursts (GRBs). Here, we report on the multi-wavelength counterpart of FXT EP240414a, which has no reported gamma-ray counterpart. The transient is located 25.7~kpc in projection from a massive galaxy at $z=0.40$. We perform comprehensive photometric and spectroscopic follow-up. The optical light curve shows at least three distinct emission episodes with timescales of $\sim 1, 4$ and 15 days and peak absolute magnitudes of $M_R \sim -20$, $-21$, and $-19.5$, respectively. The optical spectrum at early times is extremely blue, inconsistent with afterglow emission. It may arise from the interaction of both jet and supernova shock waves with the stellar envelope and a dense circumstellar medium, as has been suggested for some Fast Blue Optical Transients (LFBOTs). At late times, the spectrum evolves to a broad-lined~Type~Ic supernova, similar to those seen in collapsar long-GRBs. This implies that the progenitor of EP240414a is a massive star creating a jet-forming supernova inside a dense envelope, resulting in an X-ray outburst with a luminosity of $\sim 10^{48}$ erg s$^{-1}$, and the complex observed optical/IR light curves. If correct, this argues for a causal link between the progenitors of long-GRBs, FXTs and LFBOTs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.19056v1-abstract-full').style.display = 'none'; document.getElementById('2409.19056v1-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 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 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">36 pages, 13 figures, submitted 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/2409.07686">arXiv:2409.07686</a> <span> [<a href="https://arxiv.org/pdf/2409.07686">pdf</a>, <a href="https://arxiv.org/format/2409.07686">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/ad85e9">10.3847/2041-8213/ad85e9 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The early radio afterglow of short GRB 230217A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Anderson%2C+G+E">G. E. Anderson</a>, <a href="/search/astro-ph?searchtype=author&query=Schroeder%2C+G">G. Schroeder</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Rhodes%2C+L">L. Rhodes</a>, <a href="/search/astro-ph?searchtype=author&query=Rowlinson%2C+A">A. Rowlinson</a>, <a href="/search/astro-ph?searchtype=author&query=Bahramian%2C+A">A. Bahramian</a>, <a href="/search/astro-ph?searchtype=author&query=Chastain%2C+S+I">S. I. Chastain</a>, <a href="/search/astro-ph?searchtype=author&query=Gompertz%2C+B+P">B. P. Gompertz</a>, <a href="/search/astro-ph?searchtype=author&query=Hancock%2C+P+J">P. J. Hancock</a>, <a href="/search/astro-ph?searchtype=author&query=Laskar%2C+T">T. Laskar</a>, <a href="/search/astro-ph?searchtype=author&query=Leung%2C+J+K">J. K. Leung</a>, <a href="/search/astro-ph?searchtype=author&query=Wijers%2C+R+A+M+J">R. A. M. J. Wijers</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="2409.07686v2-abstract-short" style="display: inline;"> We present the radio afterglow of short gamma-ray burst (GRB) 230217A, which was detected less than 1 day after the gamma-ray prompt emission with the Australia Telescope Compact Array (ATCA) and the Karl G. Jansky Very Large Array (VLA). The ATCA rapid-response system automatically triggered an observation of GRB 230217A following its detection by the Neil Gehrels Swift Observatory and began obse… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.07686v2-abstract-full').style.display = 'inline'; document.getElementById('2409.07686v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.07686v2-abstract-full" style="display: none;"> We present the radio afterglow of short gamma-ray burst (GRB) 230217A, which was detected less than 1 day after the gamma-ray prompt emission with the Australia Telescope Compact Array (ATCA) and the Karl G. Jansky Very Large Array (VLA). The ATCA rapid-response system automatically triggered an observation of GRB 230217A following its detection by the Neil Gehrels Swift Observatory and began observing the event just 32 minutes post-burst at 5.5 and 9 GHz for 7 hours. Dividing the 7-hour observation into three time-binned images allowed us to obtain radio detections with logarithmic central times of 1, 2.8 and 5.2 hours post-burst, the first of which represents the earliest radio detection of any GRB to date. The decline of the light curve is consistent with reverse shock emission if the observing bands are below the spectral peak and not affected by synchrotron self-absorption. This makes GRB 230217A the fifth short GRB with radio detections attributed to a reverse shock at early times ($<1$ day post-burst). Following brightness temperature arguments, we have used our early radio detections to place the highest minimum Lorentz factor ($螕_{min} > 50$ at $\sim1$ hour) constraints on a GRB in the radio band. Our results demonstrate the importance of rapid radio follow-up observations with long integrations and good sensitivity for detecting the fast-evolving radio emission from short GRBs and probing their reverse shocks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.07686v2-abstract-full').style.display = 'none'; document.getElementById('2409.07686v2-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 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, 3 figures, submitted to ApJL</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> 2024 ApJL 975 L13 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.16637">arXiv:2408.16637</a> <span> [<a href="https://arxiv.org/pdf/2408.16637">pdf</a>, <a href="https://arxiv.org/format/2408.16637">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"> Rocking the BOAT: the ups and downs of the long-term radio light curve for GRB 221009A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Rhodes%2C+L">L. Rhodes</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Bright%2C+J+S">J. S. Bright</a>, <a href="/search/astro-ph?searchtype=author&query=Leung%2C+J+K">J. K. Leung</a>, <a href="/search/astro-ph?searchtype=author&query=Anderson%2C+G+E">G. E. Anderson</a>, <a href="/search/astro-ph?searchtype=author&query=Fender%2C+R">R. Fender</a>, <a href="/search/astro-ph?searchtype=author&query=Fernandez%2C+J+F+A">J. F. Ag眉铆 Fernandez</a>, <a href="/search/astro-ph?searchtype=author&query=Bremer%2C+M">M. Bremer</a>, <a href="/search/astro-ph?searchtype=author&query=Chandra%2C+P">P. Chandra</a>, <a href="/search/astro-ph?searchtype=author&query=Dobie%2C+D">D. Dobie</a>, <a href="/search/astro-ph?searchtype=author&query=Farah%2C+W">W. Farah</a>, <a href="/search/astro-ph?searchtype=author&query=Giarratana%2C+S">S. Giarratana</a>, <a href="/search/astro-ph?searchtype=author&query=Gourdji%2C+K">K. Gourdji</a>, <a href="/search/astro-ph?searchtype=author&query=Green%2C+D+A">D. A. Green</a>, <a href="/search/astro-ph?searchtype=author&query=Lenc%2C+E">E. Lenc</a>, <a href="/search/astro-ph?searchtype=author&query=Micha%C5%82owski%2C+M+J">M. J. Micha艂owski</a>, <a href="/search/astro-ph?searchtype=author&query=Murphy%2C+T">T. Murphy</a>, <a href="/search/astro-ph?searchtype=author&query=Nayana%2C+A+J">A. J. Nayana</a>, <a href="/search/astro-ph?searchtype=author&query=Pollak%2C+A+W">A. W. Pollak</a>, <a href="/search/astro-ph?searchtype=author&query=Rowlinson%2C+A">A. Rowlinson</a>, <a href="/search/astro-ph?searchtype=author&query=Schussler%2C+F">F. Schussler</a>, <a href="/search/astro-ph?searchtype=author&query=Siemion%2C+A">A. Siemion</a>, <a href="/search/astro-ph?searchtype=author&query=Starling%2C+R+L+C">R. L. C. Starling</a>, <a href="/search/astro-ph?searchtype=author&query=Scott%2C+P">P. Scott</a>, <a href="/search/astro-ph?searchtype=author&query=Th%C3%B6ne%2C+C+C">C. C. Th枚ne</a> , et al. (2 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="2408.16637v1-abstract-short" style="display: inline;"> We present radio observations of the long-duration gamma-ray burst (GRB) 221009A which has become known to the community as the Brightest Of All Time or the BOAT. Our observations span the first 475 days post-burst and three orders of magnitude in observing frequency, from 0.15 to 230GHz. By combining our new observations with those available in the literature, we have the most detailed radio data… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.16637v1-abstract-full').style.display = 'inline'; document.getElementById('2408.16637v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.16637v1-abstract-full" style="display: none;"> We present radio observations of the long-duration gamma-ray burst (GRB) 221009A which has become known to the community as the Brightest Of All Time or the BOAT. Our observations span the first 475 days post-burst and three orders of magnitude in observing frequency, from 0.15 to 230GHz. By combining our new observations with those available in the literature, we have the most detailed radio data set in terms of cadence and spectral coverage of any GRB to date, which we use to explore the spectral and temporal evolution of the afterglow. By testing a series of phenomenological models, we find that three separate synchrotron components best explain the afterglow. The high temporal and spectral resolution allows us to conclude that standard analytical afterglow models are unable to explain the observed evolution of GRB 221009A. We explore where the discrepancies between the observations and the models are most significant and place our findings in the context of the most well-studied GRB radio afterglows to date. Our observations are best explained by three synchrotron emitting regions which we interpret as a forward shock, a reverse shock and an additional shock potentially from a cocoon or wider outflow. Finally, we find that our observations do not show any evidence of any late-time spectral or temporal changes that could result from a jet break but note that any lateral structure could significantly affect a jet break signature. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.16637v1-abstract-full').style.display = 'none'; document.getElementById('2408.16637v1-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 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">15 pages, 8 figures. Accepted to 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/2407.11883">arXiv:2407.11883</a> <span> [<a href="https://arxiv.org/pdf/2407.11883">pdf</a>, <a href="https://arxiv.org/format/2407.11883">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"> Constraints on Short Gamma-Ray Burst Physics and Their Host Galaxies from Systematic Radio Follow-up Campaigns </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Chastain%2C+S+I">S. I. Chastain</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Anderson%2C+G+E">G. E. Anderson</a>, <a href="/search/astro-ph?searchtype=author&query=Rhodes%2C+L">L. Rhodes</a>, <a href="/search/astro-ph?searchtype=author&query=d%27Antonio%2C+D">D. d'Antonio</a>, <a href="/search/astro-ph?searchtype=author&query=Bell%2C+M+E">M. E. Bell</a>, <a href="/search/astro-ph?searchtype=author&query=Fender%2C+R+P">R. P. Fender</a>, <a href="/search/astro-ph?searchtype=author&query=Hancock%2C+P+J">P. J. Hancock</a>, <a href="/search/astro-ph?searchtype=author&query=Horesh%2C+A">A. Horesh</a>, <a href="/search/astro-ph?searchtype=author&query=Kouveliotou%2C+C">C. Kouveliotou</a>, <a href="/search/astro-ph?searchtype=author&query=Mooley%2C+K+P">K. P. Mooley</a>, <a href="/search/astro-ph?searchtype=author&query=Rowlinson%2C+A">A. Rowlinson</a>, <a href="/search/astro-ph?searchtype=author&query=Vergani%2C+S+D">S. D. Vergani</a>, <a href="/search/astro-ph?searchtype=author&query=Wijers%2C+R+A+M+J">R. A. M. J. Wijers</a>, <a href="/search/astro-ph?searchtype=author&query=Woudt%2C+P+A">P. A. Woudt</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="2407.11883v1-abstract-short" style="display: inline;"> Short gamma-ray bursts (GRBs) are explosive transients caused by binary mergers of compact objects containing at least one neutron star. Multi-wavelength afterglow observations provide constraints on the physical parameters of the jet, its surrounding medium, and the microphysics of the enhanced magnetic fields and accelerated electrons in the blast wave at the front of the jet. The synchrotron ra… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.11883v1-abstract-full').style.display = 'inline'; document.getElementById('2407.11883v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.11883v1-abstract-full" style="display: none;"> Short gamma-ray bursts (GRBs) are explosive transients caused by binary mergers of compact objects containing at least one neutron star. Multi-wavelength afterglow observations provide constraints on the physical parameters of the jet, its surrounding medium, and the microphysics of the enhanced magnetic fields and accelerated electrons in the blast wave at the front of the jet. The synchrotron radio emission can be tracked for much longer than in other spectral regimes, and it can pin down the evolution of the spectral peak. We present the results of a systematic observing campaign of eight short GRBs with the MeerKAT radio telescope. Additionally, we present observations of four of these short GRBs using the ATCA radio telescope and two of these short GRBs with the e-MERLIN radio telescope. Using these results we report one possible detection of a short GRB afterglow from GRB 230217A and deep upper limits for the rest of our short GRB observations. We use these observations to place constraints on some of the physical parameters, in particular those related to electron acceleration, the circumburst density, and gamma-ray energy efficiency. We discuss how deeper observations with new and upgraded telescopes should be able to determine if the gamma-ray efficiency differs between long and short GRBs. We also report detections of the likely host galaxies for four of the eight GRBs and upper limits for another GRB, increasing the number of detected host galaxies in the radio with implications for the star formation rate in these galaxies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.11883v1-abstract-full').style.display = 'none'; document.getElementById('2407.11883v1-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 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">to be published in the Monthly Notices of the Royal Astronomical Society</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.13126">arXiv:2403.13126</a> <span> [<a href="https://arxiv.org/pdf/2403.13126">pdf</a>, <a href="https://arxiv.org/format/2403.13126">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"> Neutral Fraction of Hydrogen in the Intergalactic Medium Surrounding High-Redshift Gamma-Ray Burst 210905A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Fausey%2C+H+M">H. M. Fausey</a>, <a href="/search/astro-ph?searchtype=author&query=Vejlgaard%2C+S">S. Vejlgaard</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Heintz%2C+K+E">K. E. Heintz</a>, <a href="/search/astro-ph?searchtype=author&query=Izzo%2C+L">L. Izzo</a>, <a href="/search/astro-ph?searchtype=author&query=Malesani%2C+D+B">D. B. Malesani</a>, <a href="/search/astro-ph?searchtype=author&query=Wiersema%2C+K">K. Wiersema</a>, <a href="/search/astro-ph?searchtype=author&query=Fynbo%2C+J+P+U">J. P. U. Fynbo</a>, <a href="/search/astro-ph?searchtype=author&query=Tanvir%2C+N+R">N. R. Tanvir</a>, <a href="/search/astro-ph?searchtype=author&query=Vergani%2C+S+D">S. D. Vergani</a>, <a href="/search/astro-ph?searchtype=author&query=Saccardi%2C+A">A. Saccardi</a>, <a href="/search/astro-ph?searchtype=author&query=Rossi%2C+A">A. Rossi</a>, <a href="/search/astro-ph?searchtype=author&query=Campana%2C+S">S. Campana</a>, <a href="/search/astro-ph?searchtype=author&query=Covino%2C+S">S. Covino</a>, <a href="/search/astro-ph?searchtype=author&query=D%27Elia%2C+V">V. D'Elia</a>, <a href="/search/astro-ph?searchtype=author&query=De+Pasquale%2C+M">M. De Pasquale</a>, <a href="/search/astro-ph?searchtype=author&query=Hartmann%2C+D">D. Hartmann</a>, <a href="/search/astro-ph?searchtype=author&query=Jakobsson%2C+P">P. Jakobsson</a>, <a href="/search/astro-ph?searchtype=author&query=Kouveliotou%2C+C">C. Kouveliotou</a>, <a href="/search/astro-ph?searchtype=author&query=Levan%2C+A">A. Levan</a>, <a href="/search/astro-ph?searchtype=author&query=Martin-Carrillo%2C+A">A. Martin-Carrillo</a>, <a href="/search/astro-ph?searchtype=author&query=Melandri%2C+A">A. Melandri</a>, <a href="/search/astro-ph?searchtype=author&query=Palmerio%2C+J">J. Palmerio</a>, <a href="/search/astro-ph?searchtype=author&query=Pugliese%2C+G">G. Pugliese</a>, <a href="/search/astro-ph?searchtype=author&query=Salvaterra%2C+R">R. Salvaterra</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="2403.13126v2-abstract-short" style="display: inline;"> The Epoch of Reionization (EoR) is a key period of cosmological history in which the intergalactic medium (IGM) underwent a major phase change from being neutral to almost completely ionized. Gamma-ray bursts (GRBs) are luminous and unique probes of their environments that can be used to study the timeline for the progression of the EoR. Here we present a detailed analysis of the ESO Very Large Te… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.13126v2-abstract-full').style.display = 'inline'; document.getElementById('2403.13126v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.13126v2-abstract-full" style="display: none;"> The Epoch of Reionization (EoR) is a key period of cosmological history in which the intergalactic medium (IGM) underwent a major phase change from being neutral to almost completely ionized. Gamma-ray bursts (GRBs) are luminous and unique probes of their environments that can be used to study the timeline for the progression of the EoR. Here we present a detailed analysis of the ESO Very Large Telescope X-shooter spectrum of GRB 210905A, which resides at a redshift of z ~ 6.3. We focus on estimating the fraction of neutral hydrogen, x_HI, on the line of sight to the host galaxy of GRB 210905A by fitting the shape of the Lyman-alpha damping wing of the afterglow spectrum. The X-shooter spectrum has a high signal to noise ratio, but the complex velocity structure of the host galaxy limits the precision of our conclusions. The statistically preferred model suggests a low neutral fraction with a 3-sigma upper limit of x_HI < 0.15 or x_HI < 0.23, depending on the absence or presence of an ionized bubble around the GRB host galaxy, indicating that the IGM around the GRB host galaxy is mostly ionized. We discuss complications in current analyses and potential avenues for future studies of the progression of the EoR and its evolution with redshift. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.13126v2-abstract-full').style.display = 'none'; document.getElementById('2403.13126v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 December, 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">19 pages, 20 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.00101">arXiv:2403.00101</a> <span> [<a href="https://arxiv.org/pdf/2403.00101">pdf</a>, <a href="https://arxiv.org/format/2403.00101">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/10.1051/0004-6361/202348159">10.1051/0004-6361/202348159 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Fires in the deep: The luminosity distribution of early-time gamma-ray-burst afterglows in light of the Gamow Explorer sensitivity requirements </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kann%2C+D+A">D. A. Kann</a>, <a href="/search/astro-ph?searchtype=author&query=White%2C+N+E">N. E. White</a>, <a href="/search/astro-ph?searchtype=author&query=Ghirlanda%2C+G">G. Ghirlanda</a>, <a href="/search/astro-ph?searchtype=author&query=Oates%2C+S+R">S. R. Oates</a>, <a href="/search/astro-ph?searchtype=author&query=Melandri%2C+A">A. Melandri</a>, <a href="/search/astro-ph?searchtype=author&query=Jelinek%2C+M">M. Jelinek</a>, <a href="/search/astro-ph?searchtype=author&query=Postigo%2C+A+d+U">A. de Ugarte Postigo</a>, <a href="/search/astro-ph?searchtype=author&query=Levan%2C+A+J">A. J. Levan</a>, <a href="/search/astro-ph?searchtype=author&query=Martin-Carrillo%2C+A">A. Martin-Carrillo</a>, <a href="/search/astro-ph?searchtype=author&query=Paek%2C+G+S+-">G. S. -H. Paek</a>, <a href="/search/astro-ph?searchtype=author&query=Izzo%2C+L">L. Izzo</a>, <a href="/search/astro-ph?searchtype=author&query=Blazek%2C+M">M. Blazek</a>, <a href="/search/astro-ph?searchtype=author&query=Thone%2C+C">C. Thone</a>, <a href="/search/astro-ph?searchtype=author&query=Fernandez%2C+J+F+A">J. F. Agui Fernandez</a>, <a href="/search/astro-ph?searchtype=author&query=Salvaterra%2C+R">R. Salvaterra</a>, <a href="/search/astro-ph?searchtype=author&query=Tanvir%2C+N+R">N. R. Tanvir</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+T+-">T. -C. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=O%27Brien%2C+P">P. O'Brien</a>, <a href="/search/astro-ph?searchtype=author&query=Rossi%2C+A">A. Rossi</a>, <a href="/search/astro-ph?searchtype=author&query=Perley%2C+D+A">D. A. Perley</a>, <a href="/search/astro-ph?searchtype=author&query=Im%2C+M">M. Im</a>, <a href="/search/astro-ph?searchtype=author&query=Malesani%2C+D+B">D. B. Malesani</a>, <a href="/search/astro-ph?searchtype=author&query=Antonelli%2C+A">A. Antonelli</a>, <a href="/search/astro-ph?searchtype=author&query=Covino%2C+S">S. Covino</a>, <a href="/search/astro-ph?searchtype=author&query=Choi%2C+C">C. Choi</a> , et al. (36 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2403.00101v1-abstract-short" style="display: inline;"> Gamma-ray bursts (GRBs) are ideal probes of the Universe at high redshift (z > 5), pinpointing the locations of the earliest star-forming galaxies and providing bright backlights that can be used to spectrally fingerprint the intergalactic medium and host galaxy during the period of reionization. Future missions such as Gamow Explorer are being proposed to unlock this potential by increasing the r… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.00101v1-abstract-full').style.display = 'inline'; document.getElementById('2403.00101v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.00101v1-abstract-full" style="display: none;"> Gamma-ray bursts (GRBs) are ideal probes of the Universe at high redshift (z > 5), pinpointing the locations of the earliest star-forming galaxies and providing bright backlights that can be used to spectrally fingerprint the intergalactic medium and host galaxy during the period of reionization. Future missions such as Gamow Explorer are being proposed to unlock this potential by increasing the rate of identification of high-z GRBs to rapidly trigger observations from 6-10 m ground telescopes, JWST, and the Extremely Large Telescopes. Gamow was proposed to the NASA 2021 Medium-Class Explorer (MIDEX) program as a fast-slewing satellite featuring a wide-field lobster-eye X-ray telescope (LEXT) to detect and localize GRBs, and a 30 cm narrow-field multi-channel photo-z infrared telescope (PIRT) to measure their photometric redshifts using the Lyman-alpha dropout technique. To derive the PIRT sensitivity requirement we compiled a complete sample of GRB optical-near-infrared afterglows from 2008 to 2021, adding a total of 66 new afterglows to our earlier sample, including all known high-z GRB afterglows. We performed full light-curve and spectral-energy-distribution analyses of these afterglows to derive their true luminosity at very early times. For all the light curves, where possible, we determined the brightness at the time of the initial finding chart of Gamow, at different high redshifts and in different NIR bands. We then followed the evolution of the luminosity to predict requirements for ground and space-based follow-up. We find that a PIRT sensitivity of 15 micro-Jy (21 mag AB) in a 500 s exposure simultaneously in five NIR bands within 1000s of the GRB trigger will meet the Gamow mission requirement to recover > 80% of all redshifts at z > 5. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.00101v1-abstract-full').style.display = 'none'; document.getElementById('2403.00101v1-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 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">44 pages, 10 figures, 1 table. Accepted for publication in Astronomy and Astrophysics 15 Feb 2024. Abstract abridged for arXiv</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 686, A56 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.04452">arXiv:2312.04452</a> <span> [<a href="https://arxiv.org/pdf/2312.04452">pdf</a>, <a href="https://arxiv.org/format/2312.04452">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> </div> </div> <p class="title is-5 mathjax"> FRAMEx. V. Radio Spectral Shape at Central Sub-parsec Region of AGNs </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Shuvo%2C+O+I">Onic I. Shuvo</a>, <a href="/search/astro-ph?searchtype=author&query=Johnson%2C+M+C">Megan C. Johnson</a>, <a href="/search/astro-ph?searchtype=author&query=Secrest%2C+N+J">Nathan J. Secrest</a>, <a href="/search/astro-ph?searchtype=author&query=Gliozzi%2C+M">Mario Gliozzi</a>, <a href="/search/astro-ph?searchtype=author&query=Cigan%2C+P+J">Phillip J. Cigan</a>, <a href="/search/astro-ph?searchtype=author&query=Fischer%2C+T+C">Travis C. Fischer</a>, <a href="/search/astro-ph?searchtype=author&query=Van+Der+Horst%2C+A+J">Alexander J. Van Der Horst</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="2312.04452v1-abstract-short" style="display: inline;"> We present results from the Very Long Baseline Array (VLBA) multi-frequency (1.6, 4.4, 8.6, 22 GHz), high-sensitivity (~25 microJy beam^-1), sub-parsec scale (<1 pc) observations and Spectral Energy Distributions (SEDs) for a sample of 12 local active galactic nuclei (AGNs), a subset from our previous volume-complete sample with hard X-ray (14-195 keV) luminosities above 10^42 erg s^-1, out to a d… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.04452v1-abstract-full').style.display = 'inline'; document.getElementById('2312.04452v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.04452v1-abstract-full" style="display: none;"> We present results from the Very Long Baseline Array (VLBA) multi-frequency (1.6, 4.4, 8.6, 22 GHz), high-sensitivity (~25 microJy beam^-1), sub-parsec scale (<1 pc) observations and Spectral Energy Distributions (SEDs) for a sample of 12 local active galactic nuclei (AGNs), a subset from our previous volume-complete sample with hard X-ray (14-195 keV) luminosities above 10^42 erg s^-1, out to a distance of 40 Mpc. All 12 of the sources presented here were detected in the C (4.4 GHz) and X (8.6 GHz) bands, 75% in the L band(1.6 GHz), and 50% in the K band (22 GHz). Most sources showed compact, resolved/slightly resolved, central sub-parsec scale radio morphology, except a few with extended outflow-like features. A couple of sources have an additional component that may indicate the presence of a dual-core, single or double-sided jet or a more intricate feature, such as radio emission resulting from interaction with nearby ISM. The spectral slopes are mostly GHz-peaked or curved, with a few showing steep, flat, or inverted spectra. We found that in the sub-parsec scale, the GHz-peaked spectra belong to the low-accreting, radio-loud AGNs with a tendency to produce strong outflows, possibly small-scale jet, and/or have a coronal origin. In contrast, flat/inverted spectra suggest compact radio emission from highly-accreting AGNs' central region, possibly associated with radio-quiet AGNs producing winds/shocks or nuclear star formation in the vicinity of black holes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.04452v1-abstract-full').style.display = 'none'; document.getElementById('2312.04452v1-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 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">23 pages, 7 figures; Accepted for publication in ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.04237">arXiv:2312.04237</a> <span> [<a href="https://arxiv.org/pdf/2312.04237">pdf</a>, <a href="https://arxiv.org/format/2312.04237">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> A candidate coherent radio flash following a neutron star merger </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Rowlinson%2C+A">A. Rowlinson</a>, <a href="/search/astro-ph?searchtype=author&query=de+Ruiter%2C+I">I. de Ruiter</a>, <a href="/search/astro-ph?searchtype=author&query=Starling%2C+R+L+C">R. L. C. Starling</a>, <a href="/search/astro-ph?searchtype=author&query=Rajwade%2C+K+M">K. M. Rajwade</a>, <a href="/search/astro-ph?searchtype=author&query=Hennessy%2C+A">A. Hennessy</a>, <a href="/search/astro-ph?searchtype=author&query=Wijers%2C+R+A+M+J">R. A. M. J. Wijers</a>, <a href="/search/astro-ph?searchtype=author&query=Anderson%2C+G+E">G. E. Anderson</a>, <a href="/search/astro-ph?searchtype=author&query=Mevius%2C+M">M. Mevius</a>, <a href="/search/astro-ph?searchtype=author&query=Ruhe%2C+D">D. Ruhe</a>, <a href="/search/astro-ph?searchtype=author&query=Gourdji%2C+K">K. Gourdji</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=ter+Veen%2C+S">S. ter Veen</a>, <a href="/search/astro-ph?searchtype=author&query=Wiersema%2C+K">K. Wiersema</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="2312.04237v3-abstract-short" style="display: inline;"> In this paper, we present rapid follow-up observations of the short GRB 201006A, consistent with being a compact binary merger, using the LOw Frequency ARray (LOFAR). We have detected a candidate 5.6$蟽$, short, coherent radio flash at 144 MHz at 76.6 mins post-GRB with a 3$蟽$ duration of 38 seconds. This radio flash is 27 arcsec offset from the GRB location, which has a probability of occurring by… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.04237v3-abstract-full').style.display = 'inline'; document.getElementById('2312.04237v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.04237v3-abstract-full" style="display: none;"> In this paper, we present rapid follow-up observations of the short GRB 201006A, consistent with being a compact binary merger, using the LOw Frequency ARray (LOFAR). We have detected a candidate 5.6$蟽$, short, coherent radio flash at 144 MHz at 76.6 mins post-GRB with a 3$蟽$ duration of 38 seconds. This radio flash is 27 arcsec offset from the GRB location, which has a probability of occurring by chance of $\sim$0.05% (3.8$蟽$) when accounting for measurement uncertainties. Despite the offset, we show that the probability of finding an unrelated transient within 40 arcsec of the GRB location is $<10^{-6}$ and conclude that this is a candidate radio counterpart to GRB 201006A. We performed image plane dedispersion and the radio flash is tentatively (2.4$蟽$) shown to be highly dispersed, allowing a distance estimate, corresponding to a redshift of $0.58\pm0.06$. The corresponding luminosity of the event at this distance is $6.7^{+6.6}_{-4.4} \times 10^{32}$ erg s$^{-1}$ Hz$^{-1}$. If associated with GRB 201006A, this emission would indicate prolonged activity from the central engine that is consistent with being a newborn, supramassive, likely highly magnetised, millisecond spin neutron star (a magnetar). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.04237v3-abstract-full').style.display = 'none'; document.getElementById('2312.04237v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 7 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">MNRAS Accepted</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2311.18833">arXiv:2311.18833</a> <span> [<a href="https://arxiv.org/pdf/2311.18833">pdf</a>, <a href="https://arxiv.org/format/2311.18833">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> </div> </div> <p class="title is-5 mathjax"> VLA FRAMEx. I. Wideband Radio Properties of the AGN in NGC 4388 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Sargent%2C+A+J">Andrew J. Sargent</a>, <a href="/search/astro-ph?searchtype=author&query=Fischer%2C+T+C">Travis C. Fischer</a>, <a href="/search/astro-ph?searchtype=author&query=Johnson%2C+M+C">Megan C. Johnson</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">Alexander J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Secrest%2C+N+J">Nathan J. Secrest</a>, <a href="/search/astro-ph?searchtype=author&query=Shuvo%2C+O+I">Onic I. Shuvo</a>, <a href="/search/astro-ph?searchtype=author&query=Cigan%2C+P+J">Phil J. Cigan</a>, <a href="/search/astro-ph?searchtype=author&query=Smith%2C+K+L">Krista L. Smith</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2311.18833v1-abstract-short" style="display: inline;"> We present the first results from Karl G. Jansky Very Large Array (VLA) observations as a part of the Fundamental Reference Active Galactic Nucleus (AGN) Monitoring Experiment (FRAMEx), a program to understand the relationship between AGN accretion physics and wavelength-dependent position as a function of time. With this VLA survey, we investigate the radio properties from a volume-complete sampl… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.18833v1-abstract-full').style.display = 'inline'; document.getElementById('2311.18833v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.18833v1-abstract-full" style="display: none;"> We present the first results from Karl G. Jansky Very Large Array (VLA) observations as a part of the Fundamental Reference Active Galactic Nucleus (AGN) Monitoring Experiment (FRAMEx), a program to understand the relationship between AGN accretion physics and wavelength-dependent position as a function of time. With this VLA survey, we investigate the radio properties from a volume-complete sample of 25 hard X-ray-selected AGNs using the VLA in its wideband mode. We observed the targets in the A-array configuration at $4-12$ GHz with all polarization products. In this work, we introduce our calibration and imaging methods for this survey, and we present our results and analysis for the radio quiet AGN NGC 4388. We calibrated and imaged these data using the multi-term, multi-frequency synthesis imaging algorithm to determine its spatial, spectral and polarization structure across a continuous $4-12$ GHz band. In the AGN, we measure a broken power law spectrum with $伪=-0.06$ below a break frequency of 7.3 GHz and $伪=-0.34$ above. We detect polarization at sub-arcsecond resolution across both the AGN and a secondary radio knot. We compare our results to ancillary data and find that the VLA radio continuum is likely due to AGN winds interacting with the local interstellar medium that gets resolved away at sub-parsec spatial scales as probed by the Very Long Baseline Array. A well-known ionization cone to the southwest of the AGN appears likely to be projected material onto the underside of the disk of the host galaxy. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.18833v1-abstract-full').style.display = 'none'; document.getElementById('2311.18833v1-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 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">22 pages, 9 figures, Accepted in ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2311.05527">arXiv:2311.05527</a> <span> [<a href="https://arxiv.org/pdf/2311.05527">pdf</a>, <a href="https://arxiv.org/format/2311.05527">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/10.1051/0004-6361/202348524">10.1051/0004-6361/202348524 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The expansion of the GRB 221009A afterglow </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Giarratana%2C+S">S. Giarratana</a>, <a href="/search/astro-ph?searchtype=author&query=Salafia%2C+O+S">O. S. Salafia</a>, <a href="/search/astro-ph?searchtype=author&query=Giroletti%2C+M">M. Giroletti</a>, <a href="/search/astro-ph?searchtype=author&query=Ghirlanda%2C+G">G. Ghirlanda</a>, <a href="/search/astro-ph?searchtype=author&query=Rhodes%2C+L">L. Rhodes</a>, <a href="/search/astro-ph?searchtype=author&query=Atri%2C+P">P. Atri</a>, <a href="/search/astro-ph?searchtype=author&query=Marcote%2C+B">B. Marcote</a>, <a href="/search/astro-ph?searchtype=author&query=Yang%2C+J">J. Yang</a>, <a href="/search/astro-ph?searchtype=author&query=An%2C+T">T. An</a>, <a href="/search/astro-ph?searchtype=author&query=Anderson%2C+G">G. Anderson</a>, <a href="/search/astro-ph?searchtype=author&query=Bright%2C+J+S">J. S. Bright</a>, <a href="/search/astro-ph?searchtype=author&query=Farah%2C+W">W. Farah</a>, <a href="/search/astro-ph?searchtype=author&query=Fender%2C+R">R. Fender</a>, <a href="/search/astro-ph?searchtype=author&query=Leung%2C+J+K">J. K. Leung</a>, <a href="/search/astro-ph?searchtype=author&query=Motta%2C+S+E">S. E. Motta</a>, <a href="/search/astro-ph?searchtype=author&query=P%C3%A9rez-Torres%2C+M">M. P茅rez-Torres</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2311.05527v3-abstract-short" style="display: inline;"> We observed $纬$-ray burst (GRB) 221009A using very long baseline interferomety (VLBI) with the European VLBI Network (EVN) and the Very Long Baseline Array (VLBA), over a period spanning from 40 to 262 days after the initial GRB. The high angular resolution (mas) of our observations allowed us, for the second time ever, after GRB 030329, to measure the projected size, $s$, of the relativistic shoc… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.05527v3-abstract-full').style.display = 'inline'; document.getElementById('2311.05527v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.05527v3-abstract-full" style="display: none;"> We observed $纬$-ray burst (GRB) 221009A using very long baseline interferomety (VLBI) with the European VLBI Network (EVN) and the Very Long Baseline Array (VLBA), over a period spanning from 40 to 262 days after the initial GRB. The high angular resolution (mas) of our observations allowed us, for the second time ever, after GRB 030329, to measure the projected size, $s$, of the relativistic shock caused by the expansion of the GRB ejecta into the surrounding medium. Our observations support the expansion of the shock with a $>4蟽$-equivalent significance, and confirm its relativistic nature by revealing an apparently superluminal expansion rate. Fitting a power law expansion model, $s\propto t^a$, to the observed size evolution, we find a slope $a=0.69^{+0.13}_{-0.14}$. Fitting the data at each frequency separately, we find different expansion rates, pointing to a frequency-dependent behaviour. We show that the observed size evolution can be reconciled with a reverse shock plus forward shock, provided that the two shocks dominate the emission at different frequencies and, possibly, at different times. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.05527v3-abstract-full').style.display = 'none'; document.getElementById('2311.05527v3-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 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted version for publication</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 690, A74 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.03093">arXiv:2310.03093</a> <span> [<a href="https://arxiv.org/pdf/2310.03093">pdf</a>, <a href="https://arxiv.org/format/2310.03093">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Photometric Redshift Estimation for Gamma-Ray Bursts from the Early Universe </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Fausey%2C+H+M">H. M. Fausey</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=White%2C+N+E">N. E. White</a>, <a href="/search/astro-ph?searchtype=author&query=Seiffert%2C+M">M. Seiffert</a>, <a href="/search/astro-ph?searchtype=author&query=Willems%2C+P">P. Willems</a>, <a href="/search/astro-ph?searchtype=author&query=Young%2C+E+T">E. T. Young</a>, <a href="/search/astro-ph?searchtype=author&query=Kann%2C+D+A">D. A. Kann</a>, <a href="/search/astro-ph?searchtype=author&query=Ghirlanda%2C+G">G. Ghirlanda</a>, <a href="/search/astro-ph?searchtype=author&query=Salvaterra%2C+R">R. Salvaterra</a>, <a href="/search/astro-ph?searchtype=author&query=Tanvir%2C+N+R">N. R. Tanvir</a>, <a href="/search/astro-ph?searchtype=author&query=Levan%2C+A">A. Levan</a>, <a href="/search/astro-ph?searchtype=author&query=Moss%2C+M">M. Moss</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+T">T-C. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Fruchter%2C+A">A. Fruchter</a>, <a href="/search/astro-ph?searchtype=author&query=Guiriec%2C+S">S. Guiriec</a>, <a href="/search/astro-ph?searchtype=author&query=Hartmann%2C+D+H">D. H. Hartmann</a>, <a href="/search/astro-ph?searchtype=author&query=Kouveliotou%2C+C">C. Kouveliotou</a>, <a href="/search/astro-ph?searchtype=author&query=Granot%2C+J">J. Granot</a>, <a href="/search/astro-ph?searchtype=author&query=Lidz%2C+A">A. Lidz</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="2310.03093v1-abstract-short" style="display: inline;"> Future detection of high-redshift gamma-ray bursts (GRBs) will be an important tool for studying the early Universe. Fast and accurate redshift estimation for detected GRBs is key for encouraging rapid follow-up observations by ground- and space-based telescopes. Low-redshift dusty interlopers pose the biggest challenge for GRB redshift estimation using broad photometric bands, as their high extin… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.03093v1-abstract-full').style.display = 'inline'; document.getElementById('2310.03093v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.03093v1-abstract-full" style="display: none;"> Future detection of high-redshift gamma-ray bursts (GRBs) will be an important tool for studying the early Universe. Fast and accurate redshift estimation for detected GRBs is key for encouraging rapid follow-up observations by ground- and space-based telescopes. Low-redshift dusty interlopers pose the biggest challenge for GRB redshift estimation using broad photometric bands, as their high extinction can mimic a high-redshift GRB. To assess false alarms of high-redshift GRB photometric measurements, we simulate and fit a variety of GRBs using phozzy, a simulation code developed to estimate GRB photometric redshifts, and test the ability to distinguish between high- and low-redshift GRBs when using simultaneously observed photometric bands. We run the code with the wavelength bands and instrument parameters for the Photo-z Infrared Telescope (PIRT), an instrument designed for the Gamow mission concept. We explore various distributions of host galaxy extinction as a function of redshift, and their effect on the completeness and purity of a high-redshift GRB search with the PIRT. We find that for assumptions based on current observations, the completeness and purity range from $\sim 82$ to $88\%$ and from $\sim 84$ to $>99\%$, respectively. For the priors optimized to reduce false positives, only $\sim 0.6\%$ of low-redshift GRBs will be mistaken as a high-redshift one, corresponding to $\sim 1$ false alarm per 500 detected GRBs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.03093v1-abstract-full').style.display = 'none'; document.getElementById('2310.03093v1-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 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">14 pages, 15 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/2309.08004">arXiv:2309.08004</a> <span> [<a href="https://arxiv.org/pdf/2309.08004">pdf</a>, <a href="https://arxiv.org/format/2309.08004">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> </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/stad2714">10.1093/mnras/stad2714 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Commensal Transient Searches in Eight Short Gamma Ray Burst Fields </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Chastain%2C+S+I">S. I. Chastain</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Rowlinson%2C+A">A. Rowlinson</a>, <a href="/search/astro-ph?searchtype=author&query=Rhodes%2C+L">L. Rhodes</a>, <a href="/search/astro-ph?searchtype=author&query=Andersson%2C+A">A. Andersson</a>, <a href="/search/astro-ph?searchtype=author&query=Diretse%2C+R">R. Diretse</a>, <a href="/search/astro-ph?searchtype=author&query=Fender%2C+R+P">R. P. Fender</a>, <a href="/search/astro-ph?searchtype=author&query=Woudt%2C+P+A">P. A. Woudt</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="2309.08004v1-abstract-short" style="display: inline;"> A new generation of radio telescopes with excellent sensitivity, instantaneous {\it uv} coverage, and large fields of view, are providing unprecedented opportunities for performing commensal transient searches. Here we present such a commensal search in deep observations of short gamma-ray burst fields carried out with the MeerKAT radio telescope in South Africa at 1.3 GHz. These four hour observa… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.08004v1-abstract-full').style.display = 'inline'; document.getElementById('2309.08004v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.08004v1-abstract-full" style="display: none;"> A new generation of radio telescopes with excellent sensitivity, instantaneous {\it uv} coverage, and large fields of view, are providing unprecedented opportunities for performing commensal transient searches. Here we present such a commensal search in deep observations of short gamma-ray burst fields carried out with the MeerKAT radio telescope in South Africa at 1.3 GHz. These four hour observations of eight different fields span survey lengths of weeks to months. We also carry out transient searches in time slices of the full observations, at timescales of 15 minutes, and 8 seconds. We find 122 variable sources on the long timescales, of which 52 are likely active galactic nuclei, but there are likely also some radio flaring stars. While the variability is intrinsic in at least two cases, most of it is consistent with interstellar scintillation. In this study, we also place constraints on transient rates based on state-of-the-art transient simulations codes. We place an upper limit of $2\times10^{-4}$ transients per day per square degree for transients with peak flux of 5 mJy, and an upper limit of $2.5\times10^{-2}$ transients per day per square degree for transients with a fluence of 10 Jy ms, the minimum detectable fluence of our survey. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.08004v1-abstract-full').style.display = 'none'; document.getElementById('2309.08004v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 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">Journal ref:</span> Monthly Notices of the Royal Astronomical Society, 2023;, stad2714 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.16121">arXiv:2308.16121</a> <span> [<a href="https://arxiv.org/pdf/2308.16121">pdf</a>, <a href="https://arxiv.org/format/2308.16121">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/stad2670">10.1093/mnras/stad2670 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A LOFAR prompt search for radio emission accompanying X-ray flares in GRB 210112A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Hennessy%2C+A">A. Hennessy</a>, <a href="/search/astro-ph?searchtype=author&query=Starling%2C+R+L+C">R. L. C. Starling</a>, <a href="/search/astro-ph?searchtype=author&query=Rowlinson%2C+A">A. Rowlinson</a>, <a href="/search/astro-ph?searchtype=author&query=de+Ruiter%2C+I">I. de Ruiter</a>, <a href="/search/astro-ph?searchtype=author&query=Kumar%2C+A">A. Kumar</a>, <a href="/search/astro-ph?searchtype=author&query=Eyles-Ferris%2C+R+A+J">R. A. J. Eyles-Ferris</a>, <a href="/search/astro-ph?searchtype=author&query=Ror%2C+A+K">A. K. Ror</a>, <a href="/search/astro-ph?searchtype=author&query=Anderson%2C+G+E">G. E. Anderson</a>, <a href="/search/astro-ph?searchtype=author&query=Gourdji%2C+K">K. Gourdji</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Pandey%2C+S+B">S. B. Pandey</a>, <a href="/search/astro-ph?searchtype=author&query=Shimwell%2C+T+W">T. W. Shimwell</a>, <a href="/search/astro-ph?searchtype=author&query=Steeghs%2C+D">D. Steeghs</a>, <a href="/search/astro-ph?searchtype=author&query=Stylianou%2C+N">N. Stylianou</a>, <a href="/search/astro-ph?searchtype=author&query=ter+Veen%2C+S">S. ter Veen</a>, <a href="/search/astro-ph?searchtype=author&query=Wiersema%2C+K">K. Wiersema</a>, <a href="/search/astro-ph?searchtype=author&query=Wijers%2C+R+A+M+J">R. A. M. J. Wijers</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="2308.16121v2-abstract-short" style="display: inline;"> The composition of relativistic gamma-ray burst (GRB) jets and their emission mechanisms are still debated, and they could be matter or magnetically dominated. One way to distinguish these mechanisms arises because a Poynting flux dominated jet may produce low-frequency radio emission during the energetic prompt phase, through magnetic reconnection at the shock front. We present a search for radio… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.16121v2-abstract-full').style.display = 'inline'; document.getElementById('2308.16121v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.16121v2-abstract-full" style="display: none;"> The composition of relativistic gamma-ray burst (GRB) jets and their emission mechanisms are still debated, and they could be matter or magnetically dominated. One way to distinguish these mechanisms arises because a Poynting flux dominated jet may produce low-frequency radio emission during the energetic prompt phase, through magnetic reconnection at the shock front. We present a search for radio emission coincident with three GRB X-ray flares with the LOw Frequency ARray (LOFAR), in a rapid response mode follow-up of long GRB 210112A (at z~2) with a 2 hour duration, where our observations began 511 seconds after the initial swift-BAT trigger. Using timesliced imaging at 120-168 MHz, we obtain upper limits at 3 sigma confidence of 42 mJy averaging over 320 second snapshot images, and 87 mJy averaging over 60 second snapshot images. LOFAR's fast response time means that all three potential radio counterparts to X-ray flares are observable after accounting for dispersion at the estimated source redshift. Furthermore, the radio pulse in the magnetic wind model was expected to be detectable at our observing frequency and flux density limits which allows us to disfavour a region of parameter space for this GRB. However, we note that stricter constraints on redshift and the fraction of energy in the magnetic field are required to further test jet characteristics across the GRB population. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.16121v2-abstract-full').style.display = 'none'; document.getElementById('2308.16121v2-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 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 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">13 pages, 7 figures, accepted for publication in MNRAS</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> MNRAS, 526, 106-117 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.10936">arXiv:2308.10936</a> <span> [<a href="https://arxiv.org/pdf/2308.10936">pdf</a>, <a href="https://arxiv.org/format/2308.10936">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> A Radio Flare in the Long-Lived Afterglow of the Distant Short GRB 210726A: Energy Injection or a Reverse Shock from Shell Collisions? </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Schroeder%2C+G">Genevieve Schroeder</a>, <a href="/search/astro-ph?searchtype=author&query=Rhodes%2C+L">Lauren Rhodes</a>, <a href="/search/astro-ph?searchtype=author&query=Laskar%2C+T">Tanmoy Laskar</a>, <a href="/search/astro-ph?searchtype=author&query=Nugent%2C+A">Anya Nugent</a>, <a href="/search/astro-ph?searchtype=author&query=Escorial%2C+A+R">Alicia Rouco Escorial</a>, <a href="/search/astro-ph?searchtype=author&query=Rastinejad%2C+J+C">Jillian C. Rastinejad</a>, <a href="/search/astro-ph?searchtype=author&query=Fong%2C+W">Wen-fai Fong</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">Alexander J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Veres%2C+P">P茅ter Veres</a>, <a href="/search/astro-ph?searchtype=author&query=Alexander%2C+K+D">Kate D. Alexander</a>, <a href="/search/astro-ph?searchtype=author&query=Andersson%2C+A">Alex Andersson</a>, <a href="/search/astro-ph?searchtype=author&query=Berger%2C+E">Edo Berger</a>, <a href="/search/astro-ph?searchtype=author&query=Blanchard%2C+P+K">Peter K. Blanchard</a>, <a href="/search/astro-ph?searchtype=author&query=Chastain%2C+S">Sarah Chastain</a>, <a href="/search/astro-ph?searchtype=author&query=Christensen%2C+L">Lise Christensen</a>, <a href="/search/astro-ph?searchtype=author&query=Fender%2C+R">Rob Fender</a>, <a href="/search/astro-ph?searchtype=author&query=Green%2C+D+A">David A. Green</a>, <a href="/search/astro-ph?searchtype=author&query=Groot%2C+P">Paul Groot</a>, <a href="/search/astro-ph?searchtype=author&query=Heywood%2C+I">Ian Heywood</a>, <a href="/search/astro-ph?searchtype=author&query=Horesh%2C+A">Assaf Horesh</a>, <a href="/search/astro-ph?searchtype=author&query=Izzo%2C+L">Luca Izzo</a>, <a href="/search/astro-ph?searchtype=author&query=Kilpatrick%2C+C+D">Charles D. Kilpatrick</a>, <a href="/search/astro-ph?searchtype=author&query=K%C3%B6rding%2C+E">Elmar K枚rding</a>, <a href="/search/astro-ph?searchtype=author&query=Lien%2C+A">Amy Lien</a>, <a href="/search/astro-ph?searchtype=author&query=Malesani%2C+D+B">Daniele B. Malesani</a> , et al. (10 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="2308.10936v2-abstract-short" style="display: inline;"> We present the discovery of the radio afterglow of the short $纬$-ray burst (GRB) 210726A, localized to a galaxy at a photometric redshift of $z\sim 2.4$. While radio observations commenced $\lesssim 1~$day after the burst, no radio emission was detected until $\sim11~$days. The radio afterglow subsequently brightened by a factor of $\sim 3$ in the span of a week, followed by a rapid decay (a "radi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.10936v2-abstract-full').style.display = 'inline'; document.getElementById('2308.10936v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.10936v2-abstract-full" style="display: none;"> We present the discovery of the radio afterglow of the short $纬$-ray burst (GRB) 210726A, localized to a galaxy at a photometric redshift of $z\sim 2.4$. While radio observations commenced $\lesssim 1~$day after the burst, no radio emission was detected until $\sim11~$days. The radio afterglow subsequently brightened by a factor of $\sim 3$ in the span of a week, followed by a rapid decay (a "radio flare"). We find that a forward shock afterglow model cannot self-consistently describe the multi-wavelength X-ray and radio data, and underpredicts the flux of the radio flare by a factor of $\approx 5$. We find that the addition of substantial energy injection, which increases the isotropic kinetic energy of the burst by a factor of $\approx 4$, or a reverse shock from a shell collision are viable solutions to match the broad-band behavior. At $z\sim 2.4$, GRB 210726A is among the highest redshift short GRBs discovered to date as well as the most luminous in radio and X-rays. Combining and comparing all previous radio afterglow observations of short GRBs, we find that the majority of published radio searches conclude by $\lesssim 10~$days after the burst, potentially missing these late rising, luminous radio afterglows. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.10936v2-abstract-full').style.display = 'none'; document.getElementById('2308.10936v2-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 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 21 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">29 pages, 10 figures, accepted to ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.13959">arXiv:2307.13959</a> <span> [<a href="https://arxiv.org/pdf/2307.13959">pdf</a>, <a href="https://arxiv.org/format/2307.13959">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> </div> <p class="title is-5 mathjax"> Swift Deep Galactic Plane Survey Classification of Swift J170800$-$402551.8 as a Candidate Intermediate Polar Cataclysmic Variable </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=O%27Connor%2C+B">B. O'Connor</a>, <a href="/search/astro-ph?searchtype=author&query=Gogus%2C+E">E. Gogus</a>, <a href="/search/astro-ph?searchtype=author&query=Hare%2C+J">J. Hare</a>, <a href="/search/astro-ph?searchtype=author&query=Mukai%2C+K">K. Mukai</a>, <a href="/search/astro-ph?searchtype=author&query=Huppenkothen%2C+D">D. Huppenkothen</a>, <a href="/search/astro-ph?searchtype=author&query=Brink%2C+J">J. Brink</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+D+A+H">D. A. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Levan%2C+A">A. Levan</a>, <a href="/search/astro-ph?searchtype=author&query=Baring%2C+M+G">M. G. Baring</a>, <a href="/search/astro-ph?searchtype=author&query=Stewart%2C+R">R. Stewart</a>, <a href="/search/astro-ph?searchtype=author&query=Kouveliotou%2C+C">C. Kouveliotou</a>, <a href="/search/astro-ph?searchtype=author&query=Woudt%2C+P">P. Woudt</a>, <a href="/search/astro-ph?searchtype=author&query=Bellm%2C+E">E. Bellm</a>, <a href="/search/astro-ph?searchtype=author&query=Cenko%2C+S+B">S. B. Cenko</a>, <a href="/search/astro-ph?searchtype=author&query=Evans%2C+P+A">P. A. Evans</a>, <a href="/search/astro-ph?searchtype=author&query=Granot%2C+J">J. Granot</a>, <a href="/search/astro-ph?searchtype=author&query=Hailey%2C+C">C. Hailey</a>, <a href="/search/astro-ph?searchtype=author&query=Harrison%2C+F">F. Harrison</a>, <a href="/search/astro-ph?searchtype=author&query=Hartmann%2C+D">D. Hartmann</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Kaper%2C+L">L. Kaper</a>, <a href="/search/astro-ph?searchtype=author&query=Kennea%2C+J+A">J. A. Kennea</a>, <a href="/search/astro-ph?searchtype=author&query=Potter%2C+S+B">S. B. Potter</a>, <a href="/search/astro-ph?searchtype=author&query=Slane%2C+P+O">P. O. Slane</a>, <a href="/search/astro-ph?searchtype=author&query=Stern%2C+D">D. Stern</a> , et al. (2 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="2307.13959v3-abstract-short" style="display: inline;"> Here, we present the results of our multi-wavelength campaign aimed at classifying \textit{Swift} J170800$-$402551.8 as part of the \textit{Swift} Deep Galactic Plane Survey (DGPS). We utilized Target of Opportunity (ToO) observations with \textit{Swift}, \textit{NICER}, \textit{XMM-Newton}, \textit{NuSTAR}, and the Southern African Large Telescope (SALT), as well as multi-wavelength archival obse… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.13959v3-abstract-full').style.display = 'inline'; document.getElementById('2307.13959v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.13959v3-abstract-full" style="display: none;"> Here, we present the results of our multi-wavelength campaign aimed at classifying \textit{Swift} J170800$-$402551.8 as part of the \textit{Swift} Deep Galactic Plane Survey (DGPS). We utilized Target of Opportunity (ToO) observations with \textit{Swift}, \textit{NICER}, \textit{XMM-Newton}, \textit{NuSTAR}, and the Southern African Large Telescope (SALT), as well as multi-wavelength archival observations from \textit{Gaia}, VPHAS, and VVV. The source displays a periodicity of 784 s in our \textit{XMM-Newton} observation. The X-ray spectrum (\textit{XMM-Newton} and \textit{NuSTAR}) can be described by thermal bremsstrahlung radiation with a temperature of $kT$\,$\approx$\,$30$ keV. The phase-folded X-ray lightcurve displays a double-peaked, energy-dependent pulse-profile. We used \textit{Chandra} to precisely localize the source, allowing us to identify and study the multi-wavelength counterpart. Spectroscopy with SALT identified a Balmer H$伪$ line, and potential HeI lines, from the optical counterpart. The faintness of the counterpart ($r$\,$\approx$\,$21$ AB mag) favors a low-mass donor star. Based on these criteria, we classify \textit{Swift} J170800$-$402551.8 as a candidate intermediate polar cataclysmic variable, where the spin period of the white dwarf is 784 s. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.13959v3-abstract-full').style.display = 'none'; document.getElementById('2307.13959v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 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">Accepted 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/2306.16383">arXiv:2306.16383</a> <span> [<a href="https://arxiv.org/pdf/2306.16383">pdf</a>, <a href="https://arxiv.org/format/2306.16383">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> A new method for short duration transient detection in radio images: Searching for transient sources in MeerKAT data of NGC 5068 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Fijma%2C+S">S. Fijma</a>, <a href="/search/astro-ph?searchtype=author&query=Rowlinson%2C+A">A. Rowlinson</a>, <a href="/search/astro-ph?searchtype=author&query=Wijers%2C+R+A+M+J">R. A. M. J. Wijers</a>, <a href="/search/astro-ph?searchtype=author&query=de+Ruiter%2C+I">I. de Ruiter</a>, <a href="/search/astro-ph?searchtype=author&query=de+Blok%2C+W+J+G">W. J. G. de Blok</a>, <a href="/search/astro-ph?searchtype=author&query=Chastain%2C+S">S. Chastain</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Meyers%2C+Z+S">Z. S. Meyers</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Meulen%2C+K">K. van der Meulen</a>, <a href="/search/astro-ph?searchtype=author&query=Fender%2C+R">R. Fender</a>, <a href="/search/astro-ph?searchtype=author&query=Woudt%2C+P+A">P. A. Woudt</a>, <a href="/search/astro-ph?searchtype=author&query=Andersson%2C+A">A. Andersson</a>, <a href="/search/astro-ph?searchtype=author&query=Zijlstra%2C+A">A. Zijlstra</a>, <a href="/search/astro-ph?searchtype=author&query=Healy%2C+J">J. Healy</a>, <a href="/search/astro-ph?searchtype=author&query=Maccagni%2C+F+M">F. M. Maccagni</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="2306.16383v1-abstract-short" style="display: inline;"> Transient surveys are a vital tool in exploring the dynamic universe, with radio transients acting as beacons for explosive and highly energetic astrophysical phenomena. However, performing commensal transient surveys using radio imaging can require a significant amount of computing power, data storage and time. With the instrumentation available to us, and with new and exciting radio interferomet… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.16383v1-abstract-full').style.display = 'inline'; document.getElementById('2306.16383v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.16383v1-abstract-full" style="display: none;"> Transient surveys are a vital tool in exploring the dynamic universe, with radio transients acting as beacons for explosive and highly energetic astrophysical phenomena. However, performing commensal transient surveys using radio imaging can require a significant amount of computing power, data storage and time. With the instrumentation available to us, and with new and exciting radio interferometers in development, it is essential that we develop efficient methods to probe the radio transient sky. In this paper, we present results from an commensal short duration transient survey, on time scales of 8 seconds, 128 seconds and 1 hour, using data from the MeerKAT radio telescope. The dataset used was obtained as part of a galaxy observing campaign, and we focus on the field of NGC 5068. We present a quick, wide field imaging strategy to enable fast imaging of large datasets, and develop methods to efficiently filter detected transient candidates. No transient candidates were identified on the time scales of 8 seconds, 128 seconds and 1 hour, leading to competitive limits on the transient surface densities of $6.7{\times}10^{-5}$ deg$^{-1}$, $1.1{\times}10^{-3}$ deg$^{-1}$, and $3.2{\times}10^{-2}$ deg$^{-1}$ at sensitivities of 56.4 mJy, 19.2 mJy, and 3.9 mJy for the respective time scales. We find one possible candidate that could be associated with a stellar flare, that was rejected due to strict image quality control. Further short time-scale radio observations of this candidate could give definite results to its origin. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.16383v1-abstract-full').style.display = 'none'; document.getElementById('2306.16383v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 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">11 pages (9 main, 2 appendix), 8 figures, 2 tables. Submitted to 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/2306.14354">arXiv:2306.14354</a> <span> [<a href="https://arxiv.org/pdf/2306.14354">pdf</a>, <a href="https://arxiv.org/format/2306.14354">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> </div> <p class="title is-5 mathjax"> The Swift Deep Galactic Plane Survey (DGPS) Phase-I Catalog </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=O%27Connor%2C+B">B. O'Connor</a>, <a href="/search/astro-ph?searchtype=author&query=Kouveliotou%2C+C">C. Kouveliotou</a>, <a href="/search/astro-ph?searchtype=author&query=Evans%2C+P+A">P. A. Evans</a>, <a href="/search/astro-ph?searchtype=author&query=Gorgone%2C+N">N. Gorgone</a>, <a href="/search/astro-ph?searchtype=author&query=van+Kooten%2C+A+J">A. J. van Kooten</a>, <a href="/search/astro-ph?searchtype=author&query=Gagnon%2C+S">S. Gagnon</a>, <a href="/search/astro-ph?searchtype=author&query=Yang%2C+H">H. Yang</a>, <a href="/search/astro-ph?searchtype=author&query=Baring%2C+M+G">M. G. Baring</a>, <a href="/search/astro-ph?searchtype=author&query=Bellm%2C+E">E. Bellm</a>, <a href="/search/astro-ph?searchtype=author&query=Beniamini%2C+P">P. Beniamini</a>, <a href="/search/astro-ph?searchtype=author&query=Brink%2C+J">J. Brink</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+D+A+H">D. A. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Cenko%2C+S+B">S. B. Cenko</a>, <a href="/search/astro-ph?searchtype=author&query=Egbo%2C+O+D">O. D. Egbo</a>, <a href="/search/astro-ph?searchtype=author&query=Gogus%2C+E">E. Gogus</a>, <a href="/search/astro-ph?searchtype=author&query=Granot%2C+J">J. Granot</a>, <a href="/search/astro-ph?searchtype=author&query=Hailey%2C+C">C. Hailey</a>, <a href="/search/astro-ph?searchtype=author&query=Hare%2C+J">J. Hare</a>, <a href="/search/astro-ph?searchtype=author&query=Harrison%2C+F">F. Harrison</a>, <a href="/search/astro-ph?searchtype=author&query=Hartmann%2C+D">D. Hartmann</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Huppenkothen%2C+D">D. Huppenkothen</a>, <a href="/search/astro-ph?searchtype=author&query=Kaper%2C+L">L. Kaper</a>, <a href="/search/astro-ph?searchtype=author&query=Kargaltsev%2C+O">O. Kargaltsev</a>, <a href="/search/astro-ph?searchtype=author&query=Kennea%2C+J+A">J. A. Kennea</a> , et al. (8 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="2306.14354v3-abstract-short" style="display: inline;"> The \textit{Swift} Deep Galactic Plane Survey is a \textit{Swift} Key Project consisting of 380 tiled pointings covering 40 deg$^{2}$ of the Galactic Plane between longitude $10$\,$<$\,$|l|$\,$<$\,$30$ deg and latitude $|b|$\,$<$\,$0.5$ deg. Each pointing has a $5$ ks exposure, yielding a total of 1.9 Ms spread across the entire survey footprint. Phase-I observations were carried out between March… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.14354v3-abstract-full').style.display = 'inline'; document.getElementById('2306.14354v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.14354v3-abstract-full" style="display: none;"> The \textit{Swift} Deep Galactic Plane Survey is a \textit{Swift} Key Project consisting of 380 tiled pointings covering 40 deg$^{2}$ of the Galactic Plane between longitude $10$\,$<$\,$|l|$\,$<$\,$30$ deg and latitude $|b|$\,$<$\,$0.5$ deg. Each pointing has a $5$ ks exposure, yielding a total of 1.9 Ms spread across the entire survey footprint. Phase-I observations were carried out between March 2017 and May 2021. The Survey is complete to depth $L_X$\,$>$\,$10^{34}$ erg s$^{-1}$ to the edge of the Galaxy. The main Survey goal is to produce a rich sample of new X-ray sources and transients, while also covering a broad discovery space. Here, we introduce the Survey strategy and present a catalog of sources detected during Phase-I observations. In total, we identify 928 X-ray sources, of which 348 are unique to our X-ray catalog. We report on the characteristics of sources in our catalog and highlight sources newly classified and published by the DGPS team. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.14354v3-abstract-full').style.display = 'none'; document.getElementById('2306.14354v3-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 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 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">Accepted in ApJS. This is the final version</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.08130">arXiv:2306.08130</a> <span> [<a href="https://arxiv.org/pdf/2306.08130">pdf</a>, <a href="https://arxiv.org/format/2306.08130">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/acfcad">10.3847/2041-8213/acfcad <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quasi-Periodic Peak Energy Oscillations in X-ray Bursts from SGR J1935+2154 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Roberts%2C+O+J">Oliver J. Roberts</a>, <a href="/search/astro-ph?searchtype=author&query=Baring%2C+M+G">Matthew G. Baring</a>, <a href="/search/astro-ph?searchtype=author&query=Huppenkothen%2C+D">Daniela Huppenkothen</a>, <a href="/search/astro-ph?searchtype=author&query=Gogus%2C+E">Ersin Gogus</a>, <a href="/search/astro-ph?searchtype=author&query=Kaneko%2C+Y">Yuki Kaneko</a>, <a href="/search/astro-ph?searchtype=author&query=Kouveliotou%2C+C">Chryssa Kouveliotou</a>, <a href="/search/astro-ph?searchtype=author&query=Lin%2C+L">Lin Lin</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">Alexander J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Younes%2C+G">George Younes</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="2306.08130v1-abstract-short" style="display: inline;"> Magnetars are young neutron stars powered by the strongest magnetic fields in the Universe (10$^{13-15}$ G). Their transient X-ray emission usually manifests as short (a few hundred milliseconds), bright, energetic ($\sim$ 10$^{40-41}$ erg) X-ray bursts. Since its discovery in 2014, magnetar J1935+2154 has become one of the most prolific magnetars, exhibiting very active bursting episodes, and oth… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.08130v1-abstract-full').style.display = 'inline'; document.getElementById('2306.08130v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.08130v1-abstract-full" style="display: none;"> Magnetars are young neutron stars powered by the strongest magnetic fields in the Universe (10$^{13-15}$ G). Their transient X-ray emission usually manifests as short (a few hundred milliseconds), bright, energetic ($\sim$ 10$^{40-41}$ erg) X-ray bursts. Since its discovery in 2014, magnetar J1935+2154 has become one of the most prolific magnetars, exhibiting very active bursting episodes, and other fascinating events such as pulse timing anti-glitches and Fast Radio Bursts. Here, we present evidence for possible 42 Hz (24 ms) quasi-periodic oscillations in the $谓F_谓$ spectrum peak energy (Ep) identified in a unique burst detected with the Fermi Gamma-ray Burst Monitor in January 2022. While quasi-periodic oscillations have been previously reported in the intensity of magnetar burst lightcurves, quasi-periodic oscillations in the Ep have not. We also find an additional event from the same outburst that appears to exhibit similar character in Ep, albeit of lower statistical quality. For these two exceptional transients, such Ep oscillations can be explained by magnetospheric density and pressure perturbations. For burst-emitting plasma consisting purely of $e^+e^-$ pairs, these acoustic modes propagate along a highly magnetized flux tube of length up to around $L\sim 130$ neutron star radii, with $L$ being lower if ions are present in the emission zone. Detailed time-resolved analyses of other magnetar bursts are encouraged to evaluate the rarity of these events and their underlying mechanisms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.08130v1-abstract-full').style.display = 'none'; document.getElementById('2306.08130v1-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, 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">Journal ref:</span> ApJL 956 L27 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.05576">arXiv:2306.05576</a> <span> [<a href="https://arxiv.org/pdf/2306.05576">pdf</a>, <a href="https://arxiv.org/format/2306.05576">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"> Identification of 1RXS J165424.6-433758 as a polar cataclysmic variable </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=O%27Connor%2C+B">B. O'Connor</a>, <a href="/search/astro-ph?searchtype=author&query=Brink%2C+J">J. Brink</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+D+A+H">D. A. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Mukai%2C+K">K. Mukai</a>, <a href="/search/astro-ph?searchtype=author&query=Kouveliotou%2C+C">C. Kouveliotou</a>, <a href="/search/astro-ph?searchtype=author&query=Gogus%2C+E">E. Gogus</a>, <a href="/search/astro-ph?searchtype=author&query=Potter%2C+S+B">S. B. Potter</a>, <a href="/search/astro-ph?searchtype=author&query=Woudt%2C+P">P. Woudt</a>, <a href="/search/astro-ph?searchtype=author&query=Lien%2C+A">A. Lien</a>, <a href="/search/astro-ph?searchtype=author&query=Levan%2C+A">A. Levan</a>, <a href="/search/astro-ph?searchtype=author&query=Kargaltsev%2C+O">O. Kargaltsev</a>, <a href="/search/astro-ph?searchtype=author&query=Baring%2C+M+G">M. G. Baring</a>, <a href="/search/astro-ph?searchtype=author&query=Bellm%2C+E">E. Bellm</a>, <a href="/search/astro-ph?searchtype=author&query=Cenko%2C+S+B">S. B. Cenko</a>, <a href="/search/astro-ph?searchtype=author&query=Evans%2C+P+A">P. A. Evans</a>, <a href="/search/astro-ph?searchtype=author&query=Granot%2C+J">J. Granot</a>, <a href="/search/astro-ph?searchtype=author&query=Hailey%2C+C">C. Hailey</a>, <a href="/search/astro-ph?searchtype=author&query=Harrison%2C+F">F. Harrison</a>, <a href="/search/astro-ph?searchtype=author&query=Hartmann%2C+D">D. Hartmann</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Huppenkothen%2C+D">D. Huppenkothen</a>, <a href="/search/astro-ph?searchtype=author&query=Kaper%2C+L">L. Kaper</a>, <a href="/search/astro-ph?searchtype=author&query=Kennea%2C+J+A">J. A. Kennea</a>, <a href="/search/astro-ph?searchtype=author&query=Slane%2C+P+O">P. O. Slane</a>, <a href="/search/astro-ph?searchtype=author&query=Stern%2C+D">D. Stern</a> , et al. (3 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="2306.05576v2-abstract-short" style="display: inline;"> We present the results of our X-ray, ultraviolet, and optical follow-up campaigns of 1RXS J165424.6-433758, an X-ray source detected with the \textit{Swift} Deep Galactic Plane Survey (DGPS). The source X-ray spectrum (\textit{Swift} and \textit{NuSTAR}) is described by thermal bremsstrahlung radiation with a temperature of $kT=10.1\pm1.2$ keV, yielding an X-ray ($0.3-10$ keV) luminosity… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.05576v2-abstract-full').style.display = 'inline'; document.getElementById('2306.05576v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.05576v2-abstract-full" style="display: none;"> We present the results of our X-ray, ultraviolet, and optical follow-up campaigns of 1RXS J165424.6-433758, an X-ray source detected with the \textit{Swift} Deep Galactic Plane Survey (DGPS). The source X-ray spectrum (\textit{Swift} and \textit{NuSTAR}) is described by thermal bremsstrahlung radiation with a temperature of $kT=10.1\pm1.2$ keV, yielding an X-ray ($0.3-10$ keV) luminosity $L_X=(6.5\pm0.8)\times10^{31}$ erg s$^{-1}$ at a \textit{Gaia} distance of 460 pc. Spectroscopy with the Southern African Large Telescope (SALT) revealed a flat continuum dominated by emission features, demonstrating an inverse Balmer decrement, the $\lambda4640$ Bowen blend, almost a dozen HeI lines, and HeII $\lambda4541$, $\lambda4686$ and $位5411$. Our high-speed photometry demonstrates a preponderance of flickering and flaring episodes, and revealed the orbital period of the system, $P_\textrm{orb}=2.87$ hr, which fell well within the cataclysmic variable (CV) period gap between $2-3$ hr. These features classify 1RXS J165424.6-433758 as a nearby polar magnetic CV. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.05576v2-abstract-full').style.display = 'none'; document.getElementById('2306.05576v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 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">Accepted for publication in ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.14157">arXiv:2304.14157</a> <span> [<a href="https://arxiv.org/pdf/2304.14157">pdf</a>, <a href="https://arxiv.org/format/2304.14157">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> <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/10.1093/mnras/stad1298">10.1093/mnras/stad1298 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Bursts from Space: MeerKAT - The first citizen science project dedicated to commensal radio transients </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Andersson%2C+A">Alex Andersson</a>, <a href="/search/astro-ph?searchtype=author&query=Lintott%2C+C">Chris Lintott</a>, <a href="/search/astro-ph?searchtype=author&query=Fender%2C+R">Rob Fender</a>, <a href="/search/astro-ph?searchtype=author&query=Bright%2C+J">Joe Bright</a>, <a href="/search/astro-ph?searchtype=author&query=Carotenuto%2C+F">Francesco Carotenuto</a>, <a href="/search/astro-ph?searchtype=author&query=Driessen%2C+L">Laura Driessen</a>, <a href="/search/astro-ph?searchtype=author&query=Espinasse%2C+M">Mathilde Espinasse</a>, <a href="/search/astro-ph?searchtype=author&query=Gaseahalwe%2C+K">Kelebogile Gaseahalwe</a>, <a href="/search/astro-ph?searchtype=author&query=Heywood%2C+I">Ian Heywood</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">Alexander J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Motta%2C+S">Sara Motta</a>, <a href="/search/astro-ph?searchtype=author&query=Rhodes%2C+L">Lauren Rhodes</a>, <a href="/search/astro-ph?searchtype=author&query=Tremou%2C+E">Evangelia Tremou</a>, <a href="/search/astro-ph?searchtype=author&query=Williams%2C+D+R+A">David R. A. Williams</a>, <a href="/search/astro-ph?searchtype=author&query=Woudt%2C+P">Patrick Woudt</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+X">Xian Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Bloemen%2C+S">Steven Bloemen</a>, <a href="/search/astro-ph?searchtype=author&query=Groot%2C+P">Paul Groot</a>, <a href="/search/astro-ph?searchtype=author&query=Vreeswijk%2C+P">Paul Vreeswijk</a>, <a href="/search/astro-ph?searchtype=author&query=Giarratana%2C+S">Stefano Giarratana</a>, <a href="/search/astro-ph?searchtype=author&query=Saikia%2C+P">Payaswini Saikia</a>, <a href="/search/astro-ph?searchtype=author&query=Andersson%2C+J">Jonas Andersson</a>, <a href="/search/astro-ph?searchtype=author&query=Arroyo%2C+L+R">Lizzeth Ruiz Arroyo</a>, <a href="/search/astro-ph?searchtype=author&query=Baert%2C+L">Lo茂c Baert</a>, <a href="/search/astro-ph?searchtype=author&query=Baumann%2C+M">Matthew Baumann</a> , et al. (18 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="2304.14157v1-abstract-short" style="display: inline;"> The newest generation of radio telescopes are able to survey large areas with high sensitivity and cadence, producing data volumes that require new methods to better understand the transient sky. Here we describe the results from the first citizen science project dedicated to commensal radio transients, using data from the MeerKAT telescope with weekly cadence. Bursts from Space: MeerKAT was launc… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.14157v1-abstract-full').style.display = 'inline'; document.getElementById('2304.14157v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.14157v1-abstract-full" style="display: none;"> The newest generation of radio telescopes are able to survey large areas with high sensitivity and cadence, producing data volumes that require new methods to better understand the transient sky. Here we describe the results from the first citizen science project dedicated to commensal radio transients, using data from the MeerKAT telescope with weekly cadence. Bursts from Space: MeerKAT was launched late in 2021 and received ~89000 classifications from over 1000 volunteers in 3 months. Our volunteers discovered 142 new variable sources which, along with the known transients in our fields, allowed us to estimate that at least 2.1 per cent of radio sources are varying at 1.28 GHz at the sampled cadence and sensitivity, in line with previous work. We provide the full catalogue of these sources, the largest of candidate radio variables to date. Transient sources found with archival counterparts include a pulsar (B1845-01) and an OH maser star (OH 30.1-0.7), in addition to the recovery of known stellar flares and X-ray binary jets in our observations. Data from the MeerLICHT optical telescope, along with estimates of long time-scale variability induced by scintillation, imply that the majority of the new variables are active galactic nuclei. This tells us that citizen scientists can discover phenomena varying on time-scales from weeks to several years. The success both in terms of volunteer engagement and scientific merit warrants the continued development of the project, whilst we use the classifications from volunteers to develop machine learning techniques for finding transients. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.14157v1-abstract-full').style.display = 'none'; document.getElementById('2304.14157v1-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 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">Accepted to MNRAS, 14 pages + an appendix containing our main data table</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.09122">arXiv:2304.09122</a> <span> [<a href="https://arxiv.org/pdf/2304.09122">pdf</a>, <a href="https://arxiv.org/format/2304.09122">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/stad1189">10.1093/mnras/stad1189 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Optical darkness in short-duration $纬$-ray bursts </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Gobat%2C+C">Caden Gobat</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">Alexander J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Fitzpatrick%2C+D">David Fitzpatrick</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="2304.09122v1-abstract-short" style="display: inline;"> Gamma-ray bursts categorically produce broadband afterglow emission, but in some cases, emission in the optical band is dimmer than expected based on the contemporaneously observed X-ray flux. This phenomenon, aptly dubbed "optical darkness", has been studied extensively in long GRBs (associated with the explosive deaths of massive stars), with possible explanations ranging from host environment e… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.09122v1-abstract-full').style.display = 'inline'; document.getElementById('2304.09122v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.09122v1-abstract-full" style="display: none;"> Gamma-ray bursts categorically produce broadband afterglow emission, but in some cases, emission in the optical band is dimmer than expected based on the contemporaneously observed X-ray flux. This phenomenon, aptly dubbed "optical darkness", has been studied extensively in long GRBs (associated with the explosive deaths of massive stars), with possible explanations ranging from host environment extinction to high redshift to possibly unique emission mechanisms. However, investigations into optical darkness in short GRBs (associated with the mergers of compact object binaries) have thus far been limited. This work implements a procedure for determining the darkness of GRBs based on spectral indices calculated using temporally-matched Swift-XRT data and optical follow-up observations; presents a complete and up-to-date catalog of known short GRBs that exhibit optical darkness; and outlines some of the possible explanations for optically dark short GRBs. In the process of this analysis, we developed versatile and scalable data processing code that facilitates reproducibility and reuse of our pipeline. These analysis tools and resulting complete sample of dark short GRBs enable a systematic statistical study of the phenomenon and its origins, and reveal that optical darkness is indeed quite rare in short GRBs, and highly dependent on observing response time and observational effects. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.09122v1-abstract-full').style.display = 'none'; document.getElementById('2304.09122v1-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 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">9 pages, 10 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/2303.13583">arXiv:2303.13583</a> <span> [<a href="https://arxiv.org/pdf/2303.13583">pdf</a>, <a href="https://arxiv.org/format/2303.13583">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"> Precise Measurements of Self-absorbed Rising Reverse Shock Emission from Gamma-ray Burst 221009A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Bright%2C+J+S">Joe S. Bright</a>, <a href="/search/astro-ph?searchtype=author&query=Rhodes%2C+L">Lauren Rhodes</a>, <a href="/search/astro-ph?searchtype=author&query=Farah%2C+W">Wael Farah</a>, <a href="/search/astro-ph?searchtype=author&query=Fender%2C+R">Rob Fender</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">Alexander J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Leung%2C+J+K">James K. Leung</a>, <a href="/search/astro-ph?searchtype=author&query=Williams%2C+D+R+A">David R. A. Williams</a>, <a href="/search/astro-ph?searchtype=author&query=Anderson%2C+G+E">Gemma E. Anderson</a>, <a href="/search/astro-ph?searchtype=author&query=Atri%2C+P">Pikky Atri</a>, <a href="/search/astro-ph?searchtype=author&query=DeBoer%2C+D+R">David R. DeBoer</a>, <a href="/search/astro-ph?searchtype=author&query=Giarratana%2C+S">Stefano Giarratana</a>, <a href="/search/astro-ph?searchtype=author&query=Green%2C+D+A">David A. Green</a>, <a href="/search/astro-ph?searchtype=author&query=Heywood%2C+I">Ian Heywood</a>, <a href="/search/astro-ph?searchtype=author&query=Lenc%2C+E">Emil Lenc</a>, <a href="/search/astro-ph?searchtype=author&query=Murphy%2C+T">Tara Murphy</a>, <a href="/search/astro-ph?searchtype=author&query=Pollak%2C+A+W">Alexander W. Pollak</a>, <a href="/search/astro-ph?searchtype=author&query=Premnath%2C+P+H">Pranav H. Premnath</a>, <a href="/search/astro-ph?searchtype=author&query=Scott%2C+P+F">Paul F. Scott</a>, <a href="/search/astro-ph?searchtype=author&query=Sheikh%2C+S+Z">Sofia Z. Sheikh</a>, <a href="/search/astro-ph?searchtype=author&query=Siemion%2C+A">Andrew Siemion</a>, <a href="/search/astro-ph?searchtype=author&query=Titterington%2C+D+J">David J. Titterington</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="2303.13583v1-abstract-short" style="display: inline;"> The deaths of massive stars are sometimes accompanied by the launch of highly relativistic and collimated jets. If the jet is pointed towards Earth, we observe a "prompt" gamma-ray burst due to internal shocks or magnetic reconnection events within the jet, followed by a long-lived broadband synchrotron afterglow as the jet interacts with the circum-burst material. While there is solid observation… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.13583v1-abstract-full').style.display = 'inline'; document.getElementById('2303.13583v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.13583v1-abstract-full" style="display: none;"> The deaths of massive stars are sometimes accompanied by the launch of highly relativistic and collimated jets. If the jet is pointed towards Earth, we observe a "prompt" gamma-ray burst due to internal shocks or magnetic reconnection events within the jet, followed by a long-lived broadband synchrotron afterglow as the jet interacts with the circum-burst material. While there is solid observational evidence that emission from multiple shocks contributes to the afterglow signature, detailed studies of the reverse shock, which travels back into the explosion ejecta, are hampered by a lack of early-time observations, particularly in the radio band. We present rapid follow-up radio observations of the exceptionally bright gamma-ray burst GRB 221009A which reveal an optically thick rising component from the reverse shock in unprecedented detail both temporally and in frequency space. From this, we are able to constrain the size, Lorentz factor, and internal energy of the outflow while providing accurate predictions for the location of the peak frequency of the reverse shock in the first few hours after the burst. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.13583v1-abstract-full').style.display = 'none'; document.getElementById('2303.13583v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 March, 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">11 figures, 4 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.07906">arXiv:2302.07906</a> <span> [<a href="https://arxiv.org/pdf/2302.07906">pdf</a>, <a href="https://arxiv.org/format/2302.07906">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> A structured jet explains the extreme GRB 221009A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=O%27Connor%2C+B">B. O'Connor</a>, <a href="/search/astro-ph?searchtype=author&query=Troja%2C+E">E. Troja</a>, <a href="/search/astro-ph?searchtype=author&query=Ryan%2C+G">G. Ryan</a>, <a href="/search/astro-ph?searchtype=author&query=Beniamini%2C+P">P. Beniamini</a>, <a href="/search/astro-ph?searchtype=author&query=van+Eerten%2C+H">H. van Eerten</a>, <a href="/search/astro-ph?searchtype=author&query=Granot%2C+J">J. Granot</a>, <a href="/search/astro-ph?searchtype=author&query=Dichiara%2C+S">S. Dichiara</a>, <a href="/search/astro-ph?searchtype=author&query=Ricci%2C+R">R. Ricci</a>, <a href="/search/astro-ph?searchtype=author&query=Lipunov%2C+V">V. Lipunov</a>, <a href="/search/astro-ph?searchtype=author&query=Gillanders%2C+J+H">J. H. Gillanders</a>, <a href="/search/astro-ph?searchtype=author&query=Gill%2C+R">R. Gill</a>, <a href="/search/astro-ph?searchtype=author&query=Moss%2C+M">M. Moss</a>, <a href="/search/astro-ph?searchtype=author&query=Anand%2C+S">S. Anand</a>, <a href="/search/astro-ph?searchtype=author&query=Andreoni%2C+I">I. Andreoni</a>, <a href="/search/astro-ph?searchtype=author&query=Becerra%2C+R+L">R. L. Becerra</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+D+A+H">D. A. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Butler%2C+N+R">N. R. Butler</a>, <a href="/search/astro-ph?searchtype=author&query=Cenko%2C+S+B">S. B. Cenko</a>, <a href="/search/astro-ph?searchtype=author&query=Chasovnikov%2C+A">A. Chasovnikov</a>, <a href="/search/astro-ph?searchtype=author&query=Durbak%2C+J">J. Durbak</a>, <a href="/search/astro-ph?searchtype=author&query=Francile%2C+C">C. Francile</a>, <a href="/search/astro-ph?searchtype=author&query=Hammerstein%2C+E">E. Hammerstein</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Kasliwal%2C+M">M. Kasliwal</a>, <a href="/search/astro-ph?searchtype=author&query=Kouveliotou%2C+C">C. Kouveliotou</a> , et al. (7 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="2302.07906v1-abstract-short" style="display: inline;"> Long duration gamma-ray bursts (GRBs) are powerful cosmic explosions, signaling the death of massive stars. Among them, GRB 221009A is by far the brightest burst ever observed. Due to its enormous energy ($E_\textrm{iso}\!\approx$10$^{55}$ erg) and proximity ($z\!\approx$0.15), GRB 221009A is an exceptionally rare event that pushes the limits of our theories. We present multi-wavelength observatio… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.07906v1-abstract-full').style.display = 'inline'; document.getElementById('2302.07906v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.07906v1-abstract-full" style="display: none;"> Long duration gamma-ray bursts (GRBs) are powerful cosmic explosions, signaling the death of massive stars. Among them, GRB 221009A is by far the brightest burst ever observed. Due to its enormous energy ($E_\textrm{iso}\!\approx$10$^{55}$ erg) and proximity ($z\!\approx$0.15), GRB 221009A is an exceptionally rare event that pushes the limits of our theories. We present multi-wavelength observations covering the first three months of its afterglow evolution. The X-ray brightness decays as a power-law with slope $\approx\!t^{-1.66}$, which is not consistent with standard predictions for jetted emission. We attribute this behavior to a shallow energy profile of the relativistic jet. A similar trend is observed in other energetic GRBs, suggesting that the most extreme explosions may be powered by structured jets launched by a common central engine. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.07906v1-abstract-full').style.display = 'none'; document.getElementById('2302.07906v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 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">Submitted version. 53 pages, 9 figures, 6 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/2302.07891">arXiv:2302.07891</a> <span> [<a href="https://arxiv.org/pdf/2302.07891">pdf</a>, <a href="https://arxiv.org/format/2302.07891">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 brightest GRB ever detected: GRB 221009A as a highly luminous event at z = 0.151 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Malesani%2C+D+B">D. B. Malesani</a>, <a href="/search/astro-ph?searchtype=author&query=Levan%2C+A+J">A. J. Levan</a>, <a href="/search/astro-ph?searchtype=author&query=Izzo%2C+L">L. Izzo</a>, <a href="/search/astro-ph?searchtype=author&query=Postigo%2C+A+d+U">A. de Ugarte Postigo</a>, <a href="/search/astro-ph?searchtype=author&query=Ghirlanda%2C+G">G. Ghirlanda</a>, <a href="/search/astro-ph?searchtype=author&query=Heintz%2C+K+E">K. E. Heintz</a>, <a href="/search/astro-ph?searchtype=author&query=Kann%2C+D+A">D. A. Kann</a>, <a href="/search/astro-ph?searchtype=author&query=Lamb%2C+G+P">G. P. Lamb</a>, <a href="/search/astro-ph?searchtype=author&query=Palmerio%2C+J">J. Palmerio</a>, <a href="/search/astro-ph?searchtype=author&query=Salafia%2C+O+S">O. S. Salafia</a>, <a href="/search/astro-ph?searchtype=author&query=Salvaterra%2C+R">R. Salvaterra</a>, <a href="/search/astro-ph?searchtype=author&query=Tanvir%2C+N+R">N. R. Tanvir</a>, <a href="/search/astro-ph?searchtype=author&query=Fern%C3%A1ndez%2C+J+F+A">J. F. Ag眉铆 Fern谩ndez</a>, <a href="/search/astro-ph?searchtype=author&query=Campana%2C+S">S. Campana</a>, <a href="/search/astro-ph?searchtype=author&query=Chrimes%2C+A+A">A. A. Chrimes</a>, <a href="/search/astro-ph?searchtype=author&query=D%27Avanzo%2C+P">P. D'Avanzo</a>, <a href="/search/astro-ph?searchtype=author&query=D%27Elia%2C+V">V. D'Elia</a>, <a href="/search/astro-ph?searchtype=author&query=Della+Valle%2C+M">M. Della Valle</a>, <a href="/search/astro-ph?searchtype=author&query=De+Pasquale%2C+M">M. De Pasquale</a>, <a href="/search/astro-ph?searchtype=author&query=Fynbo%2C+J+P+U">J. P. U. Fynbo</a>, <a href="/search/astro-ph?searchtype=author&query=Gaspari%2C+N">N. Gaspari</a>, <a href="/search/astro-ph?searchtype=author&query=Gompertz%2C+B+P">B. P. Gompertz</a>, <a href="/search/astro-ph?searchtype=author&query=Hartmann%2C+D+H">D. H. Hartmann</a>, <a href="/search/astro-ph?searchtype=author&query=Hjorth%2C+J">J. Hjorth</a>, <a href="/search/astro-ph?searchtype=author&query=Jakobsson%2C+P">P. Jakobsson</a> , et al. (17 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="2302.07891v2-abstract-short" style="display: inline;"> Context: The extreme luminosity of gamma-ray bursts (GRBs) makes them powerful beacons for studies of the distant Universe. The most luminous bursts are typically detected at moderate/high redshift, where the volume for seeing such rare events is maximized and the star-formation activity is greater than at z = 0. For distant events, not all observations are feasible, such as at TeV energies. Aim… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.07891v2-abstract-full').style.display = 'inline'; document.getElementById('2302.07891v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.07891v2-abstract-full" style="display: none;"> Context: The extreme luminosity of gamma-ray bursts (GRBs) makes them powerful beacons for studies of the distant Universe. The most luminous bursts are typically detected at moderate/high redshift, where the volume for seeing such rare events is maximized and the star-formation activity is greater than at z = 0. For distant events, not all observations are feasible, such as at TeV energies. Aims: Here we present a spectroscopic redshift measurement for the exceptional GRB 221009A, the brightest GRB observed to date with emission extending well into the TeV regime. Methods: We used the X-shooter spectrograph at the ESO Very Large Telescope (VLT) to obtain simultaneous optical to near-IR spectroscopy of the burst afterglow 0.5 days after the explosion. Results: The spectra exhibit both absorption and emission lines from material in a host galaxy at z = 0.151. Thus GRB 221009A was a relatively nearby burst with a luminosity distance of 745 Mpc. Its host galaxy properties (star-formation rate and metallicity) are consistent with those of LGRB hosts at low redshift. This redshift measurement yields information on the energy of the burst. The inferred isotropic energy release, $E_{\rm iso} > 5 \times 10^{54}$ erg, lies at the high end of the distribution, making GRB 221009A one of the nearest and also most energetic GRBs observed to date. We estimate that such a combination (nearby as well as intrinsically bright) occurs between once every few decades to once per millennium. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.07891v2-abstract-full').style.display = 'none'; document.getElementById('2302.07891v2-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 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 15 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">9 pages, 4 figures, Astronomy & Astrophysics, accepted</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.07761">arXiv:2302.07761</a> <span> [<a href="https://arxiv.org/pdf/2302.07761">pdf</a>, <a href="https://arxiv.org/format/2302.07761">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/acc2c1">10.3847/2041-8213/acc2c1 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The first JWST spectrum of a GRB afterglow: No bright supernova in observations of the brightest GRB of all time, GRB 221009A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Levan%2C+A+J">A. J. Levan</a>, <a href="/search/astro-ph?searchtype=author&query=Lamb%2C+G+P">G. P. Lamb</a>, <a href="/search/astro-ph?searchtype=author&query=Schneider%2C+B">B. Schneider</a>, <a href="/search/astro-ph?searchtype=author&query=Hjorth%2C+J">J. Hjorth</a>, <a href="/search/astro-ph?searchtype=author&query=Zafar%2C+T">T. Zafar</a>, <a href="/search/astro-ph?searchtype=author&query=Postigo%2C+A+d+U">A. de Ugarte Postigo</a>, <a href="/search/astro-ph?searchtype=author&query=Sargent%2C+B">B. Sargent</a>, <a href="/search/astro-ph?searchtype=author&query=Mullally%2C+S+E">S. E. Mullally</a>, <a href="/search/astro-ph?searchtype=author&query=Izzo%2C+L">L. Izzo</a>, <a href="/search/astro-ph?searchtype=author&query=D%27Avanzo%2C+P">P. D'Avanzo</a>, <a href="/search/astro-ph?searchtype=author&query=Burns%2C+E">E. Burns</a>, <a href="/search/astro-ph?searchtype=author&query=Fern%C3%A1ndez%2C+J+F+A">J. F. Ag眉铆 Fern谩ndez</a>, <a href="/search/astro-ph?searchtype=author&query=Barclay%2C+T">T. Barclay</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardini%2C+M+G">M. G. Bernardini</a>, <a href="/search/astro-ph?searchtype=author&query=Bhirombhakdi%2C+K">K. Bhirombhakdi</a>, <a href="/search/astro-ph?searchtype=author&query=Bremer%2C+M">M. Bremer</a>, <a href="/search/astro-ph?searchtype=author&query=Brivio%2C+R">R. Brivio</a>, <a href="/search/astro-ph?searchtype=author&query=Campana%2C+S">S. Campana</a>, <a href="/search/astro-ph?searchtype=author&query=Chrimes%2C+A+A">A. A. Chrimes</a>, <a href="/search/astro-ph?searchtype=author&query=D%27Elia%2C+V">V. D'Elia</a>, <a href="/search/astro-ph?searchtype=author&query=Della+Valle%2C+M">M. Della Valle</a>, <a href="/search/astro-ph?searchtype=author&query=De+Pasquale%2C+M">M. De Pasquale</a>, <a href="/search/astro-ph?searchtype=author&query=Ferro%2C+M">M. Ferro</a>, <a href="/search/astro-ph?searchtype=author&query=Fong%2C+W">W. Fong</a>, <a href="/search/astro-ph?searchtype=author&query=Fruchter%2C+A+S">A. S. Fruchter</a> , et al. (35 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="2302.07761v2-abstract-short" style="display: inline;"> We present JWST and Hubble Space Telescope (HST) observations of the afterglow of GRB 221009A, the brightest gamma-ray burst (GRB) ever observed. This includes the first mid-IR spectra of any GRB, obtained with JWST/NIRSPEC (0.6-5.5 micron) and MIRI (5-12 micron), 12 days after the burst. Assuming that the intrinsic spectral slope is a single power-law, with $F_谓 \propto 谓^{-尾}$, we obtain… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.07761v2-abstract-full').style.display = 'inline'; document.getElementById('2302.07761v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.07761v2-abstract-full" style="display: none;"> We present JWST and Hubble Space Telescope (HST) observations of the afterglow of GRB 221009A, the brightest gamma-ray burst (GRB) ever observed. This includes the first mid-IR spectra of any GRB, obtained with JWST/NIRSPEC (0.6-5.5 micron) and MIRI (5-12 micron), 12 days after the burst. Assuming that the intrinsic spectral slope is a single power-law, with $F_谓 \propto 谓^{-尾}$, we obtain $尾\approx 0.35$, modified by substantial dust extinction with $A_V = 4.9$. This suggests extinction above the notional Galactic value, possibly due to patchy extinction within the Milky Way or dust in the GRB host galaxy. It further implies that the X-ray and optical/IR regimes are not on the same segment of the synchrotron spectrum of the afterglow. If the cooling break lies between the X-ray and optical/IR, then the temporal decay rates would only match a post jet-break model, with electron index $p<2$, and with the jet expanding into a uniform ISM medium. The shape of the JWST spectrum is near-identical in the optical/nIR to X-shooter spectroscopy obtained at 0.5 days and to later time observations with HST. The lack of spectral evolution suggests that any accompanying supernova (SN) is either substantially fainter or bluer than SN 1998bw, the proto-type GRB-SN. Our HST observations also reveal a disc-like host galaxy, viewed close to edge-on, that further complicates the isolation of any supernova component. The host galaxy appears rather typical amongst long-GRB hosts and suggests that the extreme properties of GRB 221009A are not directly tied to its galaxy-scale environment. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.07761v2-abstract-full').style.display = 'none'; document.getElementById('2302.07761v2-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">v1</span> submitted 15 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">Accepted for publication to the Astrophysical Journal Letters for the GRB 221009A Special Issue. The results of this paper are under press embargo until March 28, 18 UT. 19 pages, 8 figures, 2 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.07397">arXiv:2302.07397</a> <span> [<a href="https://arxiv.org/pdf/2302.07397">pdf</a>, <a href="https://arxiv.org/format/2302.07397">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/acbc7c">10.3847/1538-4357/acbc7c <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The 2022 high-energy outburst and radio disappearing act of the magnetar 1E 1547.0-5408 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Lower%2C+M+E">Marcus E. Lower</a>, <a href="/search/astro-ph?searchtype=author&query=Younes%2C+G">George Younes</a>, <a href="/search/astro-ph?searchtype=author&query=Scholz%2C+P">Paul Scholz</a>, <a href="/search/astro-ph?searchtype=author&query=Camilo%2C+F">Fernando Camilo</a>, <a href="/search/astro-ph?searchtype=author&query=Dunn%2C+L">Liam Dunn</a>, <a href="/search/astro-ph?searchtype=author&query=Johnston%2C+S">Simon Johnston</a>, <a href="/search/astro-ph?searchtype=author&query=Enoto%2C+T">Teruaki Enoto</a>, <a href="/search/astro-ph?searchtype=author&query=Sarkissian%2C+J+M">John M. Sarkissian</a>, <a href="/search/astro-ph?searchtype=author&query=Reynolds%2C+J+E">John E. Reynolds</a>, <a href="/search/astro-ph?searchtype=author&query=Palmer%2C+D+M">David M. Palmer</a>, <a href="/search/astro-ph?searchtype=author&query=Arzoumanian%2C+Z">Zaven Arzoumanian</a>, <a href="/search/astro-ph?searchtype=author&query=Baring%2C+M+G">Matthew G. Baring</a>, <a href="/search/astro-ph?searchtype=author&query=Gendreau%2C+K">Keith Gendreau</a>, <a href="/search/astro-ph?searchtype=author&query=G%C3%B6%C4%9F%C3%BC%C5%9F%2C+E">Ersin G枚臒眉艧</a>, <a href="/search/astro-ph?searchtype=author&query=Guillot%2C+S">Sebastien Guillot</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">Alexander J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Hu%2C+C">Chin-Ping Hu</a>, <a href="/search/astro-ph?searchtype=author&query=Kouveliotou%2C+C">Chryssa Kouveliotou</a>, <a href="/search/astro-ph?searchtype=author&query=Lin%2C+L">Lin Lin</a>, <a href="/search/astro-ph?searchtype=author&query=Malacaria%2C+C">Christian Malacaria</a>, <a href="/search/astro-ph?searchtype=author&query=Stewart%2C+R">Rachael Stewart</a>, <a href="/search/astro-ph?searchtype=author&query=Wadiasingh%2C+Z">Zorawar Wadiasingh</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="2302.07397v2-abstract-short" style="display: inline;"> We report the radio and high-energy properties of a new outburst from the radio-loud magnetar 1E 1547.0$-$5408. Following the detection of a short burst from the source with Swift-BAT on 2022 April 7, observations by NICER detected an increased flux peaking at $(6.0 \pm 0.4) \times 10^{-11}$ erg s$^{-1}$ cm$^{-2}$ in the soft X-ray band, falling to the baseline level of $1.7\times10^{-11}$ erg s… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.07397v2-abstract-full').style.display = 'inline'; document.getElementById('2302.07397v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.07397v2-abstract-full" style="display: none;"> We report the radio and high-energy properties of a new outburst from the radio-loud magnetar 1E 1547.0$-$5408. Following the detection of a short burst from the source with Swift-BAT on 2022 April 7, observations by NICER detected an increased flux peaking at $(6.0 \pm 0.4) \times 10^{-11}$ erg s$^{-1}$ cm$^{-2}$ in the soft X-ray band, falling to the baseline level of $1.7\times10^{-11}$ erg s$^{-1}$ cm$^{-2}$ over a 17-day period. Joint spectroscopic measurements by NICER and NuSTAR indicated no change in the hard non-thermal tail despite the prominent increase in soft X-rays. Observations at radio wavelengths with Murriyang, the 64-m Parkes radio telescope, revealed that the persistent radio emission from the magnetar disappeared at least 22 days prior to the initial Swift-BAT detection and was re-detected two weeks later. Such behavior is unprecedented in a radio-loud magnetar, and may point to an unnoticed slow rise in the high-energy activity prior to the detected short-bursts. Finally, our combined radio and X-ray timing revealed the outburst coincided with a spin-up glitch, where the spin-frequency and spin-down rate increased by $0.2 \pm 0.1$ $渭$Hz and $(-2.4 \pm 0.1) \times 10^{-12}$ s$^{-2}$ respectively. A linear increase in spin-down rate of $(-2.0 \pm 0.1) \times 10^{-19}$ s$^{-3}$ was also observed over 147 d of post-outburst timing. Our results suggest that the outburst may have been associated with a reconfiguration of the quasi-polar field lines, likely signalling a changing twist, accompanied by spatially broader heating of the surface and a brief quenching of the radio signal, yet without any measurable impact on the hard X-ray properties. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.07397v2-abstract-full').style.display = 'none'; document.getElementById('2302.07397v2-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 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 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">Accepted to ApJ, 18 pages, 7 figures. Fixed typo in abstract and discussion</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2301.12770">arXiv:2301.12770</a> <span> [<a href="https://arxiv.org/pdf/2301.12770">pdf</a>, <a href="https://arxiv.org/format/2301.12770">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/stad344">10.1093/mnras/stad344 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Day-timescale variability in the radio light curve of the Tidal Disruption Event AT2022cmc: confirmation of a highly relativistic outflow </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Rhodes%2C+L">L. Rhodes</a>, <a href="/search/astro-ph?searchtype=author&query=Bright%2C+J+S">J. S. Bright</a>, <a href="/search/astro-ph?searchtype=author&query=Fender%2C+R">R. Fender</a>, <a href="/search/astro-ph?searchtype=author&query=Sfaradi%2C+I">I. Sfaradi</a>, <a href="/search/astro-ph?searchtype=author&query=Green%2C+D+A">D. A. Green</a>, <a href="/search/astro-ph?searchtype=author&query=Horesh%2C+A">A. Horesh</a>, <a href="/search/astro-ph?searchtype=author&query=Mooley%2C+K">K. Mooley</a>, <a href="/search/astro-ph?searchtype=author&query=Pasham%2C+D">D. Pasham</a>, <a href="/search/astro-ph?searchtype=author&query=Smartt%2C+S">S. Smartt</a>, <a href="/search/astro-ph?searchtype=author&query=Titterington%2C+D+J">D. J. Titterington</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Williams%2C+D+R+A">D. R. A. Williams</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="2301.12770v1-abstract-short" style="display: inline;"> Tidal disruption events (TDEs) are transient, multi-wavelength events in which a star is ripped apart by a supermassive black hole. Observations show that in a small fraction of TDEs, a short-lived, synchrotron emitting jet is produced. We observed the newly discovered TDE AT2022cmc with a slew of radio facilities over the first 100 days after its discovery. The light curve from the AMI-LA radio i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2301.12770v1-abstract-full').style.display = 'inline'; document.getElementById('2301.12770v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2301.12770v1-abstract-full" style="display: none;"> Tidal disruption events (TDEs) are transient, multi-wavelength events in which a star is ripped apart by a supermassive black hole. Observations show that in a small fraction of TDEs, a short-lived, synchrotron emitting jet is produced. We observed the newly discovered TDE AT2022cmc with a slew of radio facilities over the first 100 days after its discovery. The light curve from the AMI-LA radio interferometer shows day-timescale variability which we attribute to a high brightness temperature emitting region as opposed to scintillation. We measure a brightness temperature of 2x10^15 K, which is unphysical for synchrotron radiation. We suggest that the measured high brightness temperature is a result of relativistic beaming caused by a jet being launched at velocities close to the speed of light along our line of sight. We infer from day-timescale variability that the jet associated with AT2022cmc has a relativistic Doppler factor of at least 16, which corresponds to a bulk Lorentz factor of at least 8 if we are observing the jet directly on axis. Such an inference is the first conclusive evidence that the radio emission observed from some TDEs is from relativistic jets because it does not rely on an outflow model. We also compare the first 100 days of radio evolution of AT2022cmc with that of the previous bright relativistic TDE, Swift J1644, and find a remarkable similarity in their evolution. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2301.12770v1-abstract-full').style.display = 'none'; document.getElementById('2301.12770v1-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 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">7 pages, 4 figures. Accepted for publication in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2301.11985">arXiv:2301.11985</a> <span> [<a href="https://arxiv.org/pdf/2301.11985">pdf</a>, <a href="https://arxiv.org/format/2301.11985">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/10.1051/0004-6361/202244917">10.1051/0004-6361/202244917 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The triple-peaked afterglow of GRB 210731A from X-ray to radio frequencies </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=de+Wet%2C+S">S. de Wet</a>, <a href="/search/astro-ph?searchtype=author&query=Laskar%2C+T">T. Laskar</a>, <a href="/search/astro-ph?searchtype=author&query=Groot%2C+P+J">P. J. Groot</a>, <a href="/search/astro-ph?searchtype=author&query=Cavallaro%2C+F">F. Cavallaro</a>, <a href="/search/astro-ph?searchtype=author&query=Guelbenzu%2C+A+N">A. Nicuesa Guelbenzu</a>, <a href="/search/astro-ph?searchtype=author&query=Chastain%2C+S">S. Chastain</a>, <a href="/search/astro-ph?searchtype=author&query=Izzo%2C+L">L. Izzo</a>, <a href="/search/astro-ph?searchtype=author&query=Levan%2C+A">A. Levan</a>, <a href="/search/astro-ph?searchtype=author&query=Malesani%2C+D+B">D. B. Malesani</a>, <a href="/search/astro-ph?searchtype=author&query=Monageng%2C+I+M">I. M. Monageng</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Zheng%2C+W">W. Zheng</a>, <a href="/search/astro-ph?searchtype=author&query=Bloemen%2C+S">S. Bloemen</a>, <a href="/search/astro-ph?searchtype=author&query=Filippenko%2C+A+V">A. V. Filippenko</a>, <a href="/search/astro-ph?searchtype=author&query=Kann%2C+D+A">D. A. Kann</a>, <a href="/search/astro-ph?searchtype=author&query=Klose%2C+S">S. Klose</a>, <a href="/search/astro-ph?searchtype=author&query=Pieterse%2C+D+L+A">D. L. A. Pieterse</a>, <a href="/search/astro-ph?searchtype=author&query=Rau%2C+A">A. Rau</a>, <a href="/search/astro-ph?searchtype=author&query=Vreeswijk%2C+P+M">P. M. Vreeswijk</a>, <a href="/search/astro-ph?searchtype=author&query=Woudt%2C+P">P. Woudt</a>, <a href="/search/astro-ph?searchtype=author&query=Zhu%2C+Z+-">Z. -P. Zhu</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="2301.11985v1-abstract-short" style="display: inline;"> GRB 210731A was a long-duration gamma-ray burst discovered by the Burst Alert Telescope (BAT) aboard the Neil Gehrels Swift observatory. Swift triggered the wide-field, robotic MeerLICHT optical telescope in Sutherland; it began observing the BAT error circle 286 seconds after the Swift trigger and discovered the optical afterglow of GRB 210731A in its first 60-second q-band exposure. Multi-colour… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2301.11985v1-abstract-full').style.display = 'inline'; document.getElementById('2301.11985v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2301.11985v1-abstract-full" style="display: none;"> GRB 210731A was a long-duration gamma-ray burst discovered by the Burst Alert Telescope (BAT) aboard the Neil Gehrels Swift observatory. Swift triggered the wide-field, robotic MeerLICHT optical telescope in Sutherland; it began observing the BAT error circle 286 seconds after the Swift trigger and discovered the optical afterglow of GRB 210731A in its first 60-second q-band exposure. Multi-colour observations of the afterglow with MeerLICHT revealed a light curve that showed three peaks of similar brightness within the first four hours. We present the results of our follow-up campaign and interpret our observations in the framework of the synchrotron forward shock model. We performed temporal and spectral fits to determine the spectral regime and external medium density profile, and performed detailed multi-wavelength theoretical modelling of the afterglow following the last optical peak at 0.2 days to determine the intrinsic blast wave parameters. We find a preference for a stellar wind density profile consistent with a massive star origin, while our theoretical modelling results in fairly typical shock microphysics parameters. Based on the energy released in gamma-rays and the kinetic energy in the blast wave, we determine a low radiative efficiency of ~0.02. The first peak in the optical light curve is likely the onset of the afterglow. We find that energy injection into the forward shock offers the simplest explanation for the subsequent light curve evolution, and that the blast wave kinetic energy increasing by a factor of ~1000 from the first peak to the last peak is indicative of substantial energy injection. Our highest-likelihood theoretical model overpredicts the 1.4 GHz flux by a factor of approximately three with respect to our upper limits, possibly implying a population of thermal electrons within the shocked region. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2301.11985v1-abstract-full').style.display = 'none'; document.getElementById('2301.11985v1-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 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">20 pages, 8 figures, 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> 2023, A&A, 671, A116 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2211.16524">arXiv:2211.16524</a> <span> [<a href="https://arxiv.org/pdf/2211.16524">pdf</a>, <a href="https://arxiv.org/format/2211.16524">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/10.1051/0004-6361/202244205">10.1051/0004-6361/202244205 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Dissecting the interstellar medium of a z=6.3 galaxy: X-shooter spectroscopy and HST imaging of the afterglow and environment of the Swift GRB 210905A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Saccardi%2C+A">A. Saccardi</a>, <a href="/search/astro-ph?searchtype=author&query=Vergani%2C+S+D">S. D. Vergani</a>, <a href="/search/astro-ph?searchtype=author&query=De+Cia%2C+A">A. De Cia</a>, <a href="/search/astro-ph?searchtype=author&query=D%27Elia%2C+V">V. D'Elia</a>, <a href="/search/astro-ph?searchtype=author&query=Heintz%2C+K+E">K. E. Heintz</a>, <a href="/search/astro-ph?searchtype=author&query=Izzo%2C+L">L. Izzo</a>, <a href="/search/astro-ph?searchtype=author&query=Palmerio%2C+J+T">J. T. Palmerio</a>, <a href="/search/astro-ph?searchtype=author&query=Petitjean%2C+P">P. Petitjean</a>, <a href="/search/astro-ph?searchtype=author&query=Rossi%2C+A">A. Rossi</a>, <a href="/search/astro-ph?searchtype=author&query=Postigo%2C+A+d+U">A. de Ugarte Postigo</a>, <a href="/search/astro-ph?searchtype=author&query=Christensen%2C+L">L. Christensen</a>, <a href="/search/astro-ph?searchtype=author&query=Konstantopoulou%2C+C">C. Konstantopoulou</a>, <a href="/search/astro-ph?searchtype=author&query=Levan%2C+A+J">A. J. Levan</a>, <a href="/search/astro-ph?searchtype=author&query=Malesani%2C+D+B">D. B. Malesani</a>, <a href="/search/astro-ph?searchtype=author&query=M%C3%B8ller%2C+P">P. M酶ller</a>, <a href="/search/astro-ph?searchtype=author&query=Ramburuth-Hurt%2C+T">T. Ramburuth-Hurt</a>, <a href="/search/astro-ph?searchtype=author&query=Salvaterra%2C+R">R. Salvaterra</a>, <a href="/search/astro-ph?searchtype=author&query=Tanvir%2C+N+R">N. R. Tanvir</a>, <a href="/search/astro-ph?searchtype=author&query=Th%C3%B6ne%2C+C+C">C. C. Th枚ne</a>, <a href="/search/astro-ph?searchtype=author&query=Vejlgaard%2C+S">S. Vejlgaard</a>, <a href="/search/astro-ph?searchtype=author&query=Fynbo%2C+J+P+U">J. P. U. Fynbo</a>, <a href="/search/astro-ph?searchtype=author&query=Kann%2C+D+A">D. A. Kann</a>, <a href="/search/astro-ph?searchtype=author&query=Schady%2C+P">P. Schady</a>, <a href="/search/astro-ph?searchtype=author&query=Watson%2C+D+J">D. J. Watson</a>, <a href="/search/astro-ph?searchtype=author&query=Wiersema%2C+K">K. Wiersema</a> , et al. (13 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="2211.16524v2-abstract-short" style="display: inline;"> The study of the properties of galaxies in the first billion years after the Big Bang is one of the major topic of current astrophysics. Optical/near-infrared spectroscopy of the afterglows of long Gamma-ray bursts (GRBs) provide a powerful diagnostic tool to probe the interstellar medium (ISM) of their host galaxies and foreground absorbers, even up to the highest redshifts. We analyze the VLT/X-… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.16524v2-abstract-full').style.display = 'inline'; document.getElementById('2211.16524v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2211.16524v2-abstract-full" style="display: none;"> The study of the properties of galaxies in the first billion years after the Big Bang is one of the major topic of current astrophysics. Optical/near-infrared spectroscopy of the afterglows of long Gamma-ray bursts (GRBs) provide a powerful diagnostic tool to probe the interstellar medium (ISM) of their host galaxies and foreground absorbers, even up to the highest redshifts. We analyze the VLT/X-shooter afterglow spectrum of GRB 210905A, triggered by the Swift Neil Gehrels Observatory, and detect neutral-hydrogen, low-ionization, high-ionization, and fine-structure absorption lines from a complex system at z=6.3118, that we associate with the GRB host galaxy. We study the ISM properties of the host system, revealing the metallicity, kinematics and chemical abundance pattern. The total metallicity of the z~6.3 system is [M/H]=-1.72+/-0.13, after correcting for dust-depletion and taking into account alpha-element enhancement. In addition, we determine the overall amount of dust and dust-to-metal mass ratio (DTM) ([Zn/Fe]_fit=0.33+/-0.09, DTM=0.18+/-0.03). We find indications of nucleosynthesis due to massive stars and evidence of peculiar over-abundance of aluminium. From the analysis of fine-structure lines, we determine distances of several kpc for the low-ionization gas clouds closest to the GRB. Those farther distances are possibly due to the high number of ionizing photons. Using the HST/F140W image of the GRB field, we show the GRB host galaxy as well as multiple objects within 2" from the GRB. We discuss the galaxy structure and kinematics that could explain our observations, also taking into account a tentative detection of Lyman-alpha emission. Deep spectroscopic observations with VLT/MUSE and JWST will offer the unique possibility of combining our results with the ionized-gas properties, with the goal of better understanding how galaxies in the reionization era form and evolve. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.16524v2-abstract-full').style.display = 'none'; document.getElementById('2211.16524v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 January, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 29 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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 Publication (In Press on A&A) - 22 pages, 10 figures, 6 tables - Appendix: 6 figures, 3 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 671, A84 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2211.11212">arXiv:2211.11212</a> <span> [<a href="https://arxiv.org/pdf/2211.11212">pdf</a>, <a href="https://arxiv.org/format/2211.11212">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/stad1635">10.1093/mnras/stad1635 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Rapid radio brightening of GRB 210702A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Anderson%2C+G+E">G. E. Anderson</a>, <a href="/search/astro-ph?searchtype=author&query=Russell%2C+T+D">T. D. Russell</a>, <a href="/search/astro-ph?searchtype=author&query=Fausey%2C+H+M">H. M. Fausey</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Hancock%2C+P+J">P. J. Hancock</a>, <a href="/search/astro-ph?searchtype=author&query=Bahramian%2C+A">A. Bahramian</a>, <a href="/search/astro-ph?searchtype=author&query=Bell%2C+M+E">M. E. Bell</a>, <a href="/search/astro-ph?searchtype=author&query=Miller-Jones%2C+J+C+A">J. C. A. Miller-Jones</a>, <a href="/search/astro-ph?searchtype=author&query=Rowell%2C+G">G. Rowell</a>, <a href="/search/astro-ph?searchtype=author&query=Sammons%2C+M+W">M. W. Sammons</a>, <a href="/search/astro-ph?searchtype=author&query=Wijers%2C+R+A+M+J">R. A. M. J. Wijers</a>, <a href="/search/astro-ph?searchtype=author&query=Galvin%2C+T+J">T. J. Galvin</a>, <a href="/search/astro-ph?searchtype=author&query=Goodwin%2C+A+J">A. J. Goodwin</a>, <a href="/search/astro-ph?searchtype=author&query=Konno%2C+R">R. Konno</a>, <a href="/search/astro-ph?searchtype=author&query=Rowlinson%2C+A">A. Rowlinson</a>, <a href="/search/astro-ph?searchtype=author&query=Ryder%2C+S+D">S. D. Ryder</a>, <a href="/search/astro-ph?searchtype=author&query=Schussler%2C+F">F. Schussler</a>, <a href="/search/astro-ph?searchtype=author&query=Wagner%2C+S+J">S. J. Wagner</a>, <a href="/search/astro-ph?searchtype=author&query=Zhu%2C+S+J">S. J. Zhu</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="2211.11212v2-abstract-short" style="display: inline;"> We observed the rapid radio brightening of GRB 210702A with the Australian Telescope Compact Array (ATCA) just 11hr post-burst, tracking early-time radio variability over a 5hr period on ~15min timescales at 9.0, 16.7, and 21.2GHz. A broken power-law fit to the 9.0GHz light curve showed that the 5hr flare peaked at a flux density of 0.4+/-0.1mJy at ~13hr post-burst with a steep rise and decline. T… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.11212v2-abstract-full').style.display = 'inline'; document.getElementById('2211.11212v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2211.11212v2-abstract-full" style="display: none;"> We observed the rapid radio brightening of GRB 210702A with the Australian Telescope Compact Array (ATCA) just 11hr post-burst, tracking early-time radio variability over a 5hr period on ~15min timescales at 9.0, 16.7, and 21.2GHz. A broken power-law fit to the 9.0GHz light curve showed that the 5hr flare peaked at a flux density of 0.4+/-0.1mJy at ~13hr post-burst with a steep rise and decline. The observed temporal and spectral evolution are not expected in the standard internal-external shock model, where forward and reverse shock radio emission evolves on much longer timescales. The early-time (<1day) optical and X-ray light curves from the Neil Gehrels Swift Observatory demonstrated typical afterglow forward shock behaviour, allowing us to use blast wave physics to determine a likely homogeneous circumburst medium and an emitting electron population power-law index of p=2.9+/-0.1. We suggest the early-time radio flare is likely due to weak interstellar scintillation (ISS), which boosted the radio afterglow emission above the ATCA sensitivity limit on minute timescales. Using weak ISS relations, we were able to place an upper limit on the size of the blast wave of $\leq6 \times 10^{16}$cm in the plane of the sky, which is consistent with the theoretical forward shock size prediction of $8\times10^{16}$cm for GRB 210702A at ~13h post-burst. This represents the earliest ISS size constraint on a GRB blast wave to date, demonstrating the importance of rapid (<1day) radio follow-up of GRBs using several-hour integrations to capture the early afterglow evolution, and to track scintillation over a broad frequency range. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.11212v2-abstract-full').style.display = 'none'; document.getElementById('2211.11212v2-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 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 21 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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">Submitted to MNRAS 13 pages, 6 figures, 2 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2211.00686">arXiv:2211.00686</a> <span> [<a href="https://arxiv.org/pdf/2211.00686">pdf</a>, <a href="https://arxiv.org/format/2211.00686">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/stac3172">10.1093/mnras/stac3172 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Constraints on Electron Acceleration in Gamma-Ray Bursts Afterglows from Radio Peaks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Duncan%2C+R+A">Ruby A. Duncan</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">Alexander J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Beniamini%2C+P">Paz Beniamini</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="2211.00686v1-abstract-short" style="display: inline;"> Studies of gamma-ray bursts (GRBs) and their multi-wavelength afterglows have led to insights in electron acceleration and emission properties from relativistic, high-energy astrophysical sources. Broadband modeling across the electromagnetic spectrum has been the primary means of investigating the physics behind these sources, although independent diagnostic tools have been developed to inform an… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.00686v1-abstract-full').style.display = 'inline'; document.getElementById('2211.00686v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2211.00686v1-abstract-full" style="display: none;"> Studies of gamma-ray bursts (GRBs) and their multi-wavelength afterglows have led to insights in electron acceleration and emission properties from relativistic, high-energy astrophysical sources. Broadband modeling across the electromagnetic spectrum has been the primary means of investigating the physics behind these sources, although independent diagnostic tools have been developed to inform and corroborate assumptions made in particle acceleration simulations and broadband studies. We present a methodology to constrain three physical parameters related to electron acceleration in GRB blast waves: the fraction of shock energy in electrons, $蔚_e$; the fraction of electrons that gets accelerated into a power-law distribution of energies, $尉_e$; and the minimum Lorentz factor of the accelerated electrons, $纬_m$. These parameters are constrained by observations of the peaks in radio afterglow light curves and spectral energy distributions. From a sample of 49 radio afterglows, we are able to find narrow distributions for these parameters, hinting at possible universality of the blast wave microphysics, although observational bias could play a role in this. Using radio peaks and considerations related to the prompt gamma-ray emission efficiency, we constrain the allowed parameter ranges for both $蔚_e$ and $尉_e$ to within about one order of magnitude, $0.01\lesssim蔚_e\lesssim0.2$ and $0.1\lesssim尉_e\lesssim1$. Such stringent constraints are inaccessible for $尉_e$ from broadband studies due to model degeneracies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.00686v1-abstract-full').style.display = 'none'; document.getElementById('2211.00686v1-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 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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, 6 figures, 2 tables; 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/2210.11518">arXiv:2210.11518</a> <span> [<a href="https://arxiv.org/pdf/2210.11518">pdf</a>, <a href="https://arxiv.org/format/2210.11518">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"> Magnetar spin-down glitch clearing the way for FRB-like bursts and a pulsed radio episode </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Younes%2C+G">G. Younes</a>, <a href="/search/astro-ph?searchtype=author&query=Baring%2C+M+G">M. G. Baring</a>, <a href="/search/astro-ph?searchtype=author&query=Harding%2C+A+K">A. K. Harding</a>, <a href="/search/astro-ph?searchtype=author&query=Enoto%2C+T">T. Enoto</a>, <a href="/search/astro-ph?searchtype=author&query=Wadiasingh%2C+Z">Z. Wadiasingh</a>, <a href="/search/astro-ph?searchtype=author&query=Pearlman%2C+A+B">A. B. Pearlman</a>, <a href="/search/astro-ph?searchtype=author&query=Ho%2C+W+C+G">W. C. G. Ho</a>, <a href="/search/astro-ph?searchtype=author&query=Guillot%2C+S">S. Guillot</a>, <a href="/search/astro-ph?searchtype=author&query=Arzoumanian%2C+Z">Z. Arzoumanian</a>, <a href="/search/astro-ph?searchtype=author&query=Borghese%2C+A">A. Borghese</a>, <a href="/search/astro-ph?searchtype=author&query=Gendreau%2C+K">K. Gendreau</a>, <a href="/search/astro-ph?searchtype=author&query=Gogus%2C+E">E. Gogus</a>, <a href="/search/astro-ph?searchtype=author&query=Guver%2C+T">T. Guver</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Hu%2C+C+-">C. -P. Hu</a>, <a href="/search/astro-ph?searchtype=author&query=Jaisawal%2C+G+K">G. K. Jaisawal</a>, <a href="/search/astro-ph?searchtype=author&query=Kouveliotou%2C+C">C. Kouveliotou</a>, <a href="/search/astro-ph?searchtype=author&query=Lin%2C+L">L. Lin</a>, <a href="/search/astro-ph?searchtype=author&query=Majid%2C+W+A">W. A. Majid</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="2210.11518v1-abstract-short" style="display: inline;"> Magnetars are a special subset of the isolated neutron star family, with X-ray and radio emission mainly powered by the decay of their immense magnetic fields. Many attributes of magnetars remain poorly understood: spin-down glitches or the sudden reductions in the star's angular momentum, radio bursts reminiscent of extra-galactic Fast Radio Bursts (FRBs), and transient pulsed radio emission last… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.11518v1-abstract-full').style.display = 'inline'; document.getElementById('2210.11518v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.11518v1-abstract-full" style="display: none;"> Magnetars are a special subset of the isolated neutron star family, with X-ray and radio emission mainly powered by the decay of their immense magnetic fields. Many attributes of magnetars remain poorly understood: spin-down glitches or the sudden reductions in the star's angular momentum, radio bursts reminiscent of extra-galactic Fast Radio Bursts (FRBs), and transient pulsed radio emission lasting months to years. Here we unveil the detection of a large spin-down glitch event ($|螖谓/谓| = 5.8_{-1.6}^{+2.6}\times10^{-6}$) from the magnetar SGR~1935+2154 on 2020 October 5 (+/- 1 day). We find no change to the source persistent surface thermal or magnetospheric X-ray behavior, nor is there evidence of strong X-ray bursting activity. Yet, in the subsequent days, the magnetar emitted three FRB-like radio bursts followed by a month long episode of pulsed radio emission. Given the rarity of spin-down glitches and radio signals from magnetars, their approximate synchronicity suggests an association, providing pivotal clues to their origin and triggering mechanisms, with ramifications to the broader magnetar and FRB populations. We postulate that impulsive crustal plasma shedding close to the magnetic pole generates a wind that combs out magnetic field lines, rapidly reducing the star's angular momentum, while temporarily altering the magnetospheric field geometry to permit the pair creation needed to precipitate radio emission. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.11518v1-abstract-full').style.display = 'none'; document.getElementById('2210.11518v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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">51 pages, 3 tables, 8 figures. Accepted for publication in Nature Astronomy</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.09323">arXiv:2210.09323</a> <span> [<a href="https://arxiv.org/pdf/2210.09323">pdf</a>, <a href="https://arxiv.org/format/2210.09323">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stad208">10.1093/mnras/stad208 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Evidence for an abundant old population of Galactic ultra long period magnetars and implications for fast radio bursts </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Beniamini%2C+P">P. Beniamini</a>, <a href="/search/astro-ph?searchtype=author&query=Wadiasingh%2C+Z">Z. Wadiasingh</a>, <a href="/search/astro-ph?searchtype=author&query=Hare%2C+J">J. Hare</a>, <a href="/search/astro-ph?searchtype=author&query=Rajwade%2C+K">K. Rajwade</a>, <a href="/search/astro-ph?searchtype=author&query=Younes%2C+G">G. Younes</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</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="2210.09323v3-abstract-short" style="display: inline;"> Two recent discoveries, namely PSR J0901-4046 and GLEAM-X J162759.5-523504.3 (hereafter GLEAM-X J1627), have corroborated an extant population of radio-loud periodic sources with long periods (76 s and 1091 s respectively) whose emission can hardly be explained by rotation losses. We argue that GLEAM-X J1627 is a highly-magnetized object consistent with a magnetar (an ultra long period magnetar -… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.09323v3-abstract-full').style.display = 'inline'; document.getElementById('2210.09323v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.09323v3-abstract-full" style="display: none;"> Two recent discoveries, namely PSR J0901-4046 and GLEAM-X J162759.5-523504.3 (hereafter GLEAM-X J1627), have corroborated an extant population of radio-loud periodic sources with long periods (76 s and 1091 s respectively) whose emission can hardly be explained by rotation losses. We argue that GLEAM-X J1627 is a highly-magnetized object consistent with a magnetar (an ultra long period magnetar - ULPM), and demonstrate it is unlikely to be either a magnetically or a rotationally-powered white dwarf. By studying these sources together with previously detected objects, we find there are at least a handful of promising candidates for Galactic ULPMs. The detections of these objects imply a substantial number, $N \gtrsim 13000$ and $N \gtrsim 500$ for PSR J0901--4046 like and GLEAM-X J1627 like objects, respectively, within our Galaxy. These source densities, as well as cooling age limits from non-detection of thermal X-rays, Galactic offsets, timing stability and dipole spindown limits, all imply the ULPM candidates are substantially older than confirmed Galactic magnetars and that their formation channel is a common one. Their existence implies widespread survival of magnetar-like fields for several Myr, distinct from the inferred behaviour in confirmed Galactic magnetars. ULPMs may also constitute a second class of FRB progenitors which could naturally exhibit very long periodic activity windows. Finally, we show that existing radio campaigns are biased against detecting objects like these and discuss strategies for future radio and X-ray surveys to identify more such objects. We estimate that ${\cal O}(100)$ more such objects should be detected with SKA-MID and DSA-2000. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.09323v3-abstract-full').style.display = 'none'; document.getElementById('2210.09323v3-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 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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">22 pages, 10 figures. Published 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/2210.06547">arXiv:2210.06547</a> <span> [<a href="https://arxiv.org/pdf/2210.06547">pdf</a>, <a href="https://arxiv.org/format/2210.06547">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/stac2951">10.1093/mnras/stac2951 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Testing afterglow models of FRB 200428 with early post-burst observations of SGR 1935+2154 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Cooper%2C+A+J">A. J. Cooper</a>, <a href="/search/astro-ph?searchtype=author&query=Rowlinson%2C+A">A. Rowlinson</a>, <a href="/search/astro-ph?searchtype=author&query=Wijers%2C+R+A+M+J">R. A. M. J. Wijers</a>, <a href="/search/astro-ph?searchtype=author&query=Bassa%2C+C">C. Bassa</a>, <a href="/search/astro-ph?searchtype=author&query=Gourdji%2C+K">K. Gourdji</a>, <a href="/search/astro-ph?searchtype=author&query=Hessels%2C+J">J. Hessels</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Kondratiev%2C+V">V. Kondratiev</a>, <a href="/search/astro-ph?searchtype=author&query=Pleunis%2C+Z">Z. Pleunis</a>, <a href="/search/astro-ph?searchtype=author&query=Shimwell%2C+T">T. Shimwell</a>, <a href="/search/astro-ph?searchtype=author&query=ter+Veen%2C+S">S. ter Veen</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="2210.06547v1-abstract-short" style="display: inline;"> We present LOFAR imaging observations from the April/May 2020 active episode of magnetar SGR 1935+2154. We place the earliest radio limits on persistent emission following the low-luminosity fast radio burst FRB 200428 from the magnetar. We also perform an image-plane search for transient emission and find no radio flares during our observations. We examine post-FRB radio upper limits in the liter… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.06547v1-abstract-full').style.display = 'inline'; document.getElementById('2210.06547v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.06547v1-abstract-full" style="display: none;"> We present LOFAR imaging observations from the April/May 2020 active episode of magnetar SGR 1935+2154. We place the earliest radio limits on persistent emission following the low-luminosity fast radio burst FRB 200428 from the magnetar. We also perform an image-plane search for transient emission and find no radio flares during our observations. We examine post-FRB radio upper limits in the literature and find that all are consistent with the multi-wavelength afterglow predicted by the synchrotron maser shock model interpretation of FRB 200428. However, early optical observations appear to rule out the simple versions of the afterglow model with constant-density circumburst media. We show that these constraints may be mitigated by adapting the model for a wind-like environment, but only for a limited parameter range. In addition, we suggest that late-time non-thermal particle acceleration occurs within the afterglow model when the shock is no longer relativistic, which may prove vital for detecting afterglows from other Galactic FRBs. We also discuss future observing strategies for verifying either magnetospheric or maser shock FRB models via rapid radio observations of Galactic magnetars and nearby FRBs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.06547v1-abstract-full').style.display = 'none'; document.getElementById('2210.06547v1-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 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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 MNRAS</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Volume 517, Issue 4, pp.5483-5495, 2022 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2209.10228">arXiv:2209.10228</a> <span> [<a href="https://arxiv.org/pdf/2209.10228">pdf</a>, <a href="https://arxiv.org/format/2209.10228">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/stac2700">10.1093/mnras/stac2700 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Radio observations of the Black Hole X-ray Binary EXO 1846-031 re-awakening from a 34-year slumber </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Williams%2C+D+R+A">D. R. A. Williams</a>, <a href="/search/astro-ph?searchtype=author&query=Motta%2C+S+E">S. E. Motta</a>, <a href="/search/astro-ph?searchtype=author&query=Fender%2C+R">R. Fender</a>, <a href="/search/astro-ph?searchtype=author&query=Miller-Jones%2C+J+C+A">J. C. A. Miller-Jones</a>, <a href="/search/astro-ph?searchtype=author&query=Neilsen%2C+J">J. Neilsen</a>, <a href="/search/astro-ph?searchtype=author&query=Allison%2C+J+R">J. R. Allison</a>, <a href="/search/astro-ph?searchtype=author&query=Bright%2C+J">J. Bright</a>, <a href="/search/astro-ph?searchtype=author&query=Heywood%2C+I">I. Heywood</a>, <a href="/search/astro-ph?searchtype=author&query=Jacob%2C+P+F+L">P. F. L. Jacob</a>, <a href="/search/astro-ph?searchtype=author&query=Rhodes%2C+L">L. Rhodes</a>, <a href="/search/astro-ph?searchtype=author&query=Tremou%2C+E">E. Tremou</a>, <a href="/search/astro-ph?searchtype=author&query=Woudt%2C+P">P. Woudt</a>, <a href="/search/astro-ph?searchtype=author&query=Eijnden%2C+J+v+d">J. van den Eijnden</a>, <a href="/search/astro-ph?searchtype=author&query=Carotenuto%2C+F">F. Carotenuto</a>, <a href="/search/astro-ph?searchtype=author&query=Green%2C+D+A">D. A. Green</a>, <a href="/search/astro-ph?searchtype=author&query=Titterington%2C+D">D. Titterington</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Saikia%2C+P">P. Saikia</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="2209.10228v1-abstract-short" style="display: inline;"> We present radio [1.3 GHz MeerKAT, 4-8 GHz Karl G. Jansky Very Large Array (VLA) and 15.5 GHz Arcminute Microkelvin Imager Large Array (AMI-LA)] and X-ray (Swift and MAXI) data from the 2019 outburst of the candidate Black Hole X-ray Binary (BHXB) EXO 1846-031. We compute a Hardness-Intensity diagram, which shows the characteristic q-shaped hysteresis of BHXBs in outburst. EXO 1846-031 was monitor… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.10228v1-abstract-full').style.display = 'inline'; document.getElementById('2209.10228v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2209.10228v1-abstract-full" style="display: none;"> We present radio [1.3 GHz MeerKAT, 4-8 GHz Karl G. Jansky Very Large Array (VLA) and 15.5 GHz Arcminute Microkelvin Imager Large Array (AMI-LA)] and X-ray (Swift and MAXI) data from the 2019 outburst of the candidate Black Hole X-ray Binary (BHXB) EXO 1846-031. We compute a Hardness-Intensity diagram, which shows the characteristic q-shaped hysteresis of BHXBs in outburst. EXO 1846-031 was monitored weekly with MeerKAT and approximately daily with AMI-LA. The VLA observations provide sub-arcsecond-resolution images at key points in the outburst, showing moving radio components. The radio and X-ray light curves broadly follow each other, showing a peak on ~MJD 58702, followed by a short decline before a second peak between ~MJD 58731-58739. We estimate the minimum energy of these radio flares from equipartition, calculating values of $E_{\rm min} \sim$ 4$\times$10$^{41}$ and 5$\times$10$^{42}$ erg, respectively. The exact date of the return to `quiescence' is missed in the X-ray and radio observations, but we suggest that it likely occurred between MJD 58887 and 58905. From the Swift X-ray flux on MJD 58905 and assuming the soft-to-hard transition happened at 0.3-3 per cent Eddington, we calculate a distance range of 2.4-7.5\,kpc. We computed the radio:X-ray plane for EXO 1846-031 in the `hard' state, showing that it is most likely a `radio-quiet' BH, preferentially at 4.5 kpc. Using this distance and a jet inclination angle of $胃$=73$^{\circ}$, the VLA data place limits on the intrinsic jet speed of $尾_{\rm int} = 0.29c$, indicating sub-luminal jet motion. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.10228v1-abstract-full').style.display = 'none'; document.getElementById('2209.10228v1-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 September, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in MNRAS on 20 September 2022, 17 pages, 6 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2208.00965">arXiv:2208.00965</a> <span> [<a href="https://arxiv.org/pdf/2208.00965">pdf</a>, <a href="https://arxiv.org/format/2208.00965">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"> Transient Simulations for Radio Surveys </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Chastain%2C+S+I">Sarah I Chastain</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">Alexander J van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Carbone%2C+D">Dario Carbone</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="2208.00965v2-abstract-short" style="display: inline;"> Several new radio facilities have a field of view and sensitivity well suited for transient searches. This makes it more important than ever to accurately determine transient rates in radio surveys. The work presented here seeks to do this task by using Monte-Carlo simulations. In particular, the user inputs either a real or simulated observational setup, and the simulations code calculates transi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.00965v2-abstract-full').style.display = 'inline'; document.getElementById('2208.00965v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2208.00965v2-abstract-full" style="display: none;"> Several new radio facilities have a field of view and sensitivity well suited for transient searches. This makes it more important than ever to accurately determine transient rates in radio surveys. The work presented here seeks to do this task by using Monte-Carlo simulations. In particular, the user inputs either a real or simulated observational setup, and the simulations code calculates transient rate as a function of transient duration and peak flux. These simulations allow for simulating a wide variety of scenarios including observations with varying sensitivities and durations, multiple overlapping telescope pointings, and a wide variety of light curve shapes with the user having the ability to easily add more. While the current scientific focus is on the radio regime, with examples given here from the MeerKAT telescope in South Africa, the simulations code can be easily adapted to other wavelength regimes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.00965v2-abstract-full').style.display = 'none'; document.getElementById('2208.00965v2-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 August, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 1 August, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 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">Minor updates to plots</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2205.16006">arXiv:2205.16006</a> <span> [<a href="https://arxiv.org/pdf/2205.16006">pdf</a>, <a href="https://arxiv.org/format/2205.16006">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> </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/ac74be">10.3847/1538-4357/ac74be <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Wandering Black Hole Candidates in Dwarf Galaxies at VLBI Resolution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Sargent%2C+A+J">Andrew J. Sargent</a>, <a href="/search/astro-ph?searchtype=author&query=Johnson%2C+M+C">Megan C. Johnson</a>, <a href="/search/astro-ph?searchtype=author&query=Reines%2C+A+E">Amy E. Reines</a>, <a href="/search/astro-ph?searchtype=author&query=Secrest%2C+N+J">Nathan J. Secrest</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">Alexander J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Cigan%2C+P+J">Phil J. Cigan</a>, <a href="/search/astro-ph?searchtype=author&query=Darling%2C+J">Jeremy Darling</a>, <a href="/search/astro-ph?searchtype=author&query=Greene%2C+J+E">Jenny E. Greene</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="2205.16006v1-abstract-short" style="display: inline;"> Thirteen dwarf galaxies have recently been found to host radio-selected accreting massive black hole (MBH) candidates, some of which are ``wandering" in the outskirts of their hosts. We present 9 GHz Very Long Baseline Array (VLBA) observations of these sources at milliarcsecond resolution. Our observations have beam solid angles ${\sim}10^4$ times smaller than the previous Very Large Array (VLA)… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2205.16006v1-abstract-full').style.display = 'inline'; document.getElementById('2205.16006v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2205.16006v1-abstract-full" style="display: none;"> Thirteen dwarf galaxies have recently been found to host radio-selected accreting massive black hole (MBH) candidates, some of which are ``wandering" in the outskirts of their hosts. We present 9 GHz Very Long Baseline Array (VLBA) observations of these sources at milliarcsecond resolution. Our observations have beam solid angles ${\sim}10^4$ times smaller than the previous Very Large Array (VLA) observations at 9 GHz, with comparable point source sensitivities. We detect milliarcsecond-scale radio sources at the positions of the four VLA sources most distant from the photo-centers of their associated dwarf galaxies. These sources have brightness temperatures of ${>}10^6~\mathrm{K}$, consistent with active galactic nuclei (AGNs), but the significance of their preferential location at large distances ($p$-value~$=0.0014$) favors a background AGN interpretation. The VLBA non-detections toward the other 9 galaxies indicate that the VLA sources are resolved out on scales of tens of milliarcseconds, requiring extended radio emission and lower brightness temperatures consistent with either star formation or radio lobes associated with AGN activity. We explore the star formation explanation by calculating the expected radio emission for these nine VLBA non-detections, finding that about 5 have VLA luminosities that are inconsistent with this scenario. Of the remaining four, two are associated with spectroscopically confirmed AGNs that are consistent with being located at their galaxy photo-centers. There are therefore between 5 and 7 wandering MBH candidates out of the 13 galaxies we observed, although we cannot rule out background AGNs for five of them with the data in hand. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2205.16006v1-abstract-full').style.display = 'none'; document.getElementById('2205.16006v1-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 May, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 3 figures, Accepted in ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.05811">arXiv:2204.05811</a> <span> [<a href="https://arxiv.org/pdf/2204.05811">pdf</a>, <a href="https://arxiv.org/format/2204.05811">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/stac1057">10.1093/mnras/stac1057 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Jet-Cocoon Geometry in the Optically Dark, Very High Energy Gamma-ray Burst 201216C </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Rhodes%2C+L">L. Rhodes</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Fender%2C+R">R. Fender</a>, <a href="/search/astro-ph?searchtype=author&query=Aguilera-Dena%2C+D+R">D. R. Aguilera-Dena</a>, <a href="/search/astro-ph?searchtype=author&query=Bright%2C+J+S">J. S. Bright</a>, <a href="/search/astro-ph?searchtype=author&query=Vergani%2C+S">S. Vergani</a>, <a href="/search/astro-ph?searchtype=author&query=Williams%2C+D+R+A">D. R. A. Williams</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="2204.05811v1-abstract-short" style="display: inline;"> We present the results of a radio observing campaign on GRB 201216C, combined with publicly available optical and X-ray data. The detection of very high energy (VHE, >100GeV) emission by MAGIC makes this the fifth VHE GRB at time of publication. Comparison between the optical and X-ray light curves show that GRB 201216C is a dark GRB, i.e. the optical emission is significantly absorbed and is fain… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.05811v1-abstract-full').style.display = 'inline'; document.getElementById('2204.05811v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.05811v1-abstract-full" style="display: none;"> We present the results of a radio observing campaign on GRB 201216C, combined with publicly available optical and X-ray data. The detection of very high energy (VHE, >100GeV) emission by MAGIC makes this the fifth VHE GRB at time of publication. Comparison between the optical and X-ray light curves show that GRB 201216C is a dark GRB, i.e. the optical emission is significantly absorbed and is fainter than expected from the X-ray detections. Our e-MERLIN data also shows evidence of diffractive interstellar scintillation. We can study the column density along the line-of-sight to the GRB in both the host galaxy, from the damped optical light curve, and the Milky Way, via scintillation studies. We find that the afterglow is best modelled using a jet-cocoon geometry within a stellar wind environment. Fitting the data with a multi-component model we estimate that the optical, X-ray and higher-frequency radio data before ~25days originates from an ultra-relativistic jet with an isotropic equivalent kinetic energy of (0.6-10)x10^52erg and an opening angle of ~1-9deg. The lower-frequency radio emission detected by MeerKAT, from day 28 onwards, is produced by the cocoon with a kinetic energy that is between two and seven orders of magnitude lower (0.02-50)x10^48erg. The energies of the two components are comparable to those derived in simulations of such scenarios. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.05811v1-abstract-full').style.display = 'none'; document.getElementById('2204.05811v1-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 April, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 8 figures. Accepted to 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/2203.16918">arXiv:2203.16918</a> <span> [<a href="https://arxiv.org/pdf/2203.16918">pdf</a>, <a href="https://arxiv.org/format/2203.16918">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/stac2460">10.1093/mnras/stac2460 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Search and identification of transient and variable radio sources using MeerKAT observations: a case study on the MAXI J1820+070 field </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Rowlinson%2C+A">A. Rowlinson</a>, <a href="/search/astro-ph?searchtype=author&query=Meijn%2C+J">J. Meijn</a>, <a href="/search/astro-ph?searchtype=author&query=Bright%2C+J">J. Bright</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Chastain%2C+S">S. Chastain</a>, <a href="/search/astro-ph?searchtype=author&query=Fijma%2C+S">S. Fijma</a>, <a href="/search/astro-ph?searchtype=author&query=Fender%2C+R">R. Fender</a>, <a href="/search/astro-ph?searchtype=author&query=Heywood%2C+I">I. Heywood</a>, <a href="/search/astro-ph?searchtype=author&query=Wijers%2C+R+A+M+J">R. A. M. J. Wijers</a>, <a href="/search/astro-ph?searchtype=author&query=Woudt%2C+P+A">P. A. Woudt</a>, <a href="/search/astro-ph?searchtype=author&query=Andersson%2C+A">A. Andersson</a>, <a href="/search/astro-ph?searchtype=author&query=Sivakoff%2C+G+R">G. R. Sivakoff</a>, <a href="/search/astro-ph?searchtype=author&query=Tremou%2C+E">E. Tremou</a>, <a href="/search/astro-ph?searchtype=author&query=Driessen%2C+L+N">L. N. Driessen</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="2203.16918v2-abstract-short" style="display: inline;"> Many transient and variable sources detected at multiple wavelengths are also observed to vary at radio frequencies. However, these samples are typically biased towards sources that are initially detected in wide-field optical, X-ray or gamma-ray surveys. Many sources that are insufficiently bright at higher frequencies are therefore missed, leading to potential gaps in our knowledge of these sour… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.16918v2-abstract-full').style.display = 'inline'; document.getElementById('2203.16918v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2203.16918v2-abstract-full" style="display: none;"> Many transient and variable sources detected at multiple wavelengths are also observed to vary at radio frequencies. However, these samples are typically biased towards sources that are initially detected in wide-field optical, X-ray or gamma-ray surveys. Many sources that are insufficiently bright at higher frequencies are therefore missed, leading to potential gaps in our knowledge of these sources and missing populations that are not detectable in optical, X-rays or gamma-rays. Taking advantage of new state-of-the-art radio facilities that provide high quality wide-field images with fast survey speeds, we can now conduct unbiased surveys for transient and variable sources at radio frequencies. In this paper, we present an unbiased survey using observations obtained by MeerKAT, a mid-frequency ($\sim$1.4 GHz) radio array in South Africa's Karoo Desert. The observations used were obtained as part of a weekly monitoring campaign for X-ray binaries (XRBs) and we focus on the field of MAXI J1820+070. We develop methods to optimally filter transient and variable candidates that can be directly applied to other datasets. In addition to MAXI J1820+070, we identify four likely active galactic nuclei, one source that could be a Galactic source (pulsar or quiescent X-ray binary) or an AGN, and one variable pulsar. No transient sources, defined as being undetected in deep images, were identified leading to a transient surface density of $<3.7\times10^{-2}$ deg$^{-2}$ at a sensitivity of 1 mJy on timescales of one week at 1.4 GHz. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.16918v2-abstract-full').style.display = 'none'; document.getElementById('2203.16918v2-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 August, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 31 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">MNRAS Accepted, 18 pages, 17 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/2203.09806">arXiv:2203.09806</a> <span> [<a href="https://arxiv.org/pdf/2203.09806">pdf</a>, <a href="https://arxiv.org/format/2203.09806">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/10.1093/mnras/stac756">10.1093/mnras/stac756 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> 21 new long-term variables in the GX 339-4 field: two years of MeerKAT monitoring </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Driessen%2C+L+N">L. N. Driessen</a>, <a href="/search/astro-ph?searchtype=author&query=Stappers%2C+B+W">B. W. Stappers</a>, <a href="/search/astro-ph?searchtype=author&query=Tremou%2C+E">E. Tremou</a>, <a href="/search/astro-ph?searchtype=author&query=Fender%2C+R+P">R. P. Fender</a>, <a href="/search/astro-ph?searchtype=author&query=Woudt%2C+P+A">P. A. Woudt</a>, <a href="/search/astro-ph?searchtype=author&query=Armstrong%2C+R">R. Armstrong</a>, <a href="/search/astro-ph?searchtype=author&query=Bloemen%2C+S">S. Bloemen</a>, <a href="/search/astro-ph?searchtype=author&query=Groot%2C+P">P. Groot</a>, <a href="/search/astro-ph?searchtype=author&query=Heywood%2C+I">I. Heywood</a>, <a href="/search/astro-ph?searchtype=author&query=Horesh%2C+A">A. Horesh</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Koerding%2C+E">E. Koerding</a>, <a href="/search/astro-ph?searchtype=author&query=McBride%2C+V+A">V. A. McBride</a>, <a href="/search/astro-ph?searchtype=author&query=Miller-Jones%2C+J+C+A">J. C. A. Miller-Jones</a>, <a href="/search/astro-ph?searchtype=author&query=Mooley%2C+K+P">K. P. Mooley</a>, <a href="/search/astro-ph?searchtype=author&query=Rowlinson%2C+A">A. Rowlinson</a>, <a href="/search/astro-ph?searchtype=author&query=Wijers%2C+R+A+M+J">R. A. M. J. Wijers</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="2203.09806v1-abstract-short" style="display: inline;"> We present 21 new long-term variable radio sources found commensally in two years of weekly MeerKAT monitoring of the low-mass X-ray binary GX 339-4. The new sources vary on time scales of weeks to months and have a variety of light curve shapes and spectral index properties. Three of the new variable sources are coincident with multi-wavelength counterparts; and one of these is coincident with an… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.09806v1-abstract-full').style.display = 'inline'; document.getElementById('2203.09806v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2203.09806v1-abstract-full" style="display: none;"> We present 21 new long-term variable radio sources found commensally in two years of weekly MeerKAT monitoring of the low-mass X-ray binary GX 339-4. The new sources vary on time scales of weeks to months and have a variety of light curve shapes and spectral index properties. Three of the new variable sources are coincident with multi-wavelength counterparts; and one of these is coincident with an optical source in deep MeerLICHT images. For most sources, we cannot eliminate refractive scintillation of active galactic nuclei as the cause of the variability. These new variable sources represent $2.2\pm0.5$ per cent of the unresolved sources in the field, which is consistent with the 1-2 per cent variability found in past radio variability surveys. However, we expect to find short-term variable sources in the field as well as these 21 new long-term variable sources. We present the radio light curves and spectral index variability of the new variable sources, as well as the absolute astrometry and matches to coincident sources at other wavelengths. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.09806v1-abstract-full').style.display = 'none'; document.getElementById('2203.09806v1-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, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">26 pages, 17 figures, 7 tables. Accepted for publication in MNRAS 2022 March 14. Received 2022 February 17; in original form 2021 July 11</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2202.04544">arXiv:2202.04544</a> <span> [<a href="https://arxiv.org/pdf/2202.04544">pdf</a>, <a href="https://arxiv.org/format/2202.04544">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/10.1051/0004-6361/202243225">10.1051/0004-6361/202243225 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A blast from the infant Universe: the very high-z GRB 210905A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Rossi%2C+A">A. Rossi</a>, <a href="/search/astro-ph?searchtype=author&query=Frederiks%2C+D+D">D. D. Frederiks</a>, <a href="/search/astro-ph?searchtype=author&query=Kann%2C+D+A">D. A. Kann</a>, <a href="/search/astro-ph?searchtype=author&query=De+Pasquale%2C+M">M. De Pasquale</a>, <a href="/search/astro-ph?searchtype=author&query=Pian%2C+E">E. Pian</a>, <a href="/search/astro-ph?searchtype=author&query=Lamb%2C+G">G. Lamb</a>, <a href="/search/astro-ph?searchtype=author&query=D%27Avanzo%2C+P">P. D'Avanzo</a>, <a href="/search/astro-ph?searchtype=author&query=Izzo%2C+L">L. Izzo</a>, <a href="/search/astro-ph?searchtype=author&query=Levan%2C+A+J">A. J. Levan</a>, <a href="/search/astro-ph?searchtype=author&query=Malesani%2C+D+B">D. B. Malesani</a>, <a href="/search/astro-ph?searchtype=author&query=Melandri%2C+A">A. Melandri</a>, <a href="/search/astro-ph?searchtype=author&query=Guelbenzu%2C+A+N">A. Nicuesa Guelbenzu</a>, <a href="/search/astro-ph?searchtype=author&query=Schulze%2C+S">S. Schulze</a>, <a href="/search/astro-ph?searchtype=author&query=Strausbaugh%2C+R">R. Strausbaugh</a>, <a href="/search/astro-ph?searchtype=author&query=Tanvir%2C+N+R">N. R. Tanvir</a>, <a href="/search/astro-ph?searchtype=author&query=Amati%2C+L">L. Amati</a>, <a href="/search/astro-ph?searchtype=author&query=Campana%2C+S">S. Campana</a>, <a href="/search/astro-ph?searchtype=author&query=Cucchiara%2C+A">A. Cucchiara</a>, <a href="/search/astro-ph?searchtype=author&query=Ghirlanda%2C+G">G. Ghirlanda</a>, <a href="/search/astro-ph?searchtype=author&query=Della+Valle%2C+M">M. Della Valle</a>, <a href="/search/astro-ph?searchtype=author&query=Klose%2C+S">S. Klose</a>, <a href="/search/astro-ph?searchtype=author&query=Salvaterra%2C+R">R. Salvaterra</a>, <a href="/search/astro-ph?searchtype=author&query=Starling%2C+R">R. Starling</a>, <a href="/search/astro-ph?searchtype=author&query=Stratta%2C+G">G. Stratta</a>, <a href="/search/astro-ph?searchtype=author&query=Tsvetkova%2C+A+E">A. E. Tsvetkova</a> , et al. (30 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="2202.04544v2-abstract-short" style="display: inline;"> We present a detailed follow-up of the very energetic GRB 210905A at a high redshift of z = 6.312 and its luminous X-ray and optical afterglow. We obtained a photometric and spectroscopic follow-up in the optical and near-infrared (NIR), covering both the prompt and afterglow emission from a few minutes up to 20 Ms after burst. With an isotropic gamma-ray energy release of Eiso = 1.27E54 erg, GRB… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.04544v2-abstract-full').style.display = 'inline'; document.getElementById('2202.04544v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2202.04544v2-abstract-full" style="display: none;"> We present a detailed follow-up of the very energetic GRB 210905A at a high redshift of z = 6.312 and its luminous X-ray and optical afterglow. We obtained a photometric and spectroscopic follow-up in the optical and near-infrared (NIR), covering both the prompt and afterglow emission from a few minutes up to 20 Ms after burst. With an isotropic gamma-ray energy release of Eiso = 1.27E54 erg, GRB 210905A lies in the top ~7% of gamma-ray bursts (GRBs) in terms of energy released. Its afterglow is among the most luminous ever observed. It starts with a shallow evolution that can be explained by energy injection, and it is followed by a steeper decay, while the spectral energy distribution is in agreement with slow cooling in a constant-density environment within the standard fireball theory. A jet break at ~ 46.2+-16.3 d (~6.3 d rest-frame) has been observed in the X-ray light curve; however, it is hidden in the H band due to the contribution from the likely host galaxy, the fourth GRB host at z > 6 known to date. We derived a half-opening angle of 8.4+-1.0 degrees, which is the highest ever measured for a z>6 burst, but within the range covered by closer events. The resulting collimation-corrected gamma-ray energy release of 1E52 erg is also among the highest ever measured. The moderately large half-opening angle argues against recent claims of an inverse dependence of the half-opening angle on the redshift. The total jet energy is likely too large to be sustained by a standard magnetar, and it suggests that the central engine of this burst was a newly formed black hole. Despite the outstanding energetics and luminosity of both GRB 210905A and its afterglow, we demonstrate that they are consistent with those of less distant bursts, indicating that the powering mechanisms and progenitors do not evolve significantly with redshift. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.04544v2-abstract-full').style.display = 'none'; document.getElementById('2202.04544v2-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 August, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 February, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 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, 12 figures, 5 tables, accepted 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 665, A125 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2111.12592">arXiv:2111.12592</a> <span> [<a href="https://arxiv.org/pdf/2111.12592">pdf</a>, <a href="https://arxiv.org/format/2111.12592">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/ac5032">10.3847/1538-4357/ac5032 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Identification of an X-ray Pulsar in the BeXRB system IGR J18219$-$1347 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=O%27Connor%2C+B">B. O'Connor</a>, <a href="/search/astro-ph?searchtype=author&query=Gogus%2C+E">E. Gogus</a>, <a href="/search/astro-ph?searchtype=author&query=Huppenkothen%2C+D">D. Huppenkothen</a>, <a href="/search/astro-ph?searchtype=author&query=Kouveliotou%2C+C">C. Kouveliotou</a>, <a href="/search/astro-ph?searchtype=author&query=Gorgone%2C+N">N. Gorgone</a>, <a href="/search/astro-ph?searchtype=author&query=Townsend%2C+L+J">L. J. Townsend</a>, <a href="/search/astro-ph?searchtype=author&query=Calamida%2C+A">A. Calamida</a>, <a href="/search/astro-ph?searchtype=author&query=Fruchter%2C+A">A. Fruchter</a>, <a href="/search/astro-ph?searchtype=author&query=Buckley%2C+D+A+H">D. A. H. Buckley</a>, <a href="/search/astro-ph?searchtype=author&query=Baring%2C+M+G">M. G. Baring</a>, <a href="/search/astro-ph?searchtype=author&query=Kennea%2C+J+A">J. A. Kennea</a>, <a href="/search/astro-ph?searchtype=author&query=Younes%2C+G">G. Younes</a>, <a href="/search/astro-ph?searchtype=author&query=Arzoumanian%2C+Z">Z. Arzoumanian</a>, <a href="/search/astro-ph?searchtype=author&query=Bellm%2C+E">E. Bellm</a>, <a href="/search/astro-ph?searchtype=author&query=Cenko%2C+S+B">S. B. Cenko</a>, <a href="/search/astro-ph?searchtype=author&query=Gendreau%2C+K">K. Gendreau</a>, <a href="/search/astro-ph?searchtype=author&query=Granot%2C+J">J. Granot</a>, <a href="/search/astro-ph?searchtype=author&query=Hailey%2C+C">C. Hailey</a>, <a href="/search/astro-ph?searchtype=author&query=Harrison%2C+F">F. Harrison</a>, <a href="/search/astro-ph?searchtype=author&query=Hartmann%2C+D">D. Hartmann</a>, <a href="/search/astro-ph?searchtype=author&query=Kaper%2C+L">L. Kaper</a>, <a href="/search/astro-ph?searchtype=author&query=Kutyrev%2C+A">A. Kutyrev</a>, <a href="/search/astro-ph?searchtype=author&query=Slane%2C+P+O">P. O. Slane</a>, <a href="/search/astro-ph?searchtype=author&query=Stern%2C+D">D. Stern</a>, <a href="/search/astro-ph?searchtype=author&query=Troja%2C+E">E. Troja</a> , et al. (3 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="2111.12592v2-abstract-short" style="display: inline;"> We report on observations of the candidate Be/X-ray binary IGR J18219$-$1347 with \textit{Swift}/XRT, \textit{NuSTAR}, and \textit{NICER} during Type-I outbursts in March and June 2020. Our timing analysis revealed the spin period of a neutron star with $P_\textrm{spin}=52.46$ s. This periodicity, combined with the known orbital period of $72.4$ d, indicates that the system is a BeXRB. Furthermore… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.12592v2-abstract-full').style.display = 'inline'; document.getElementById('2111.12592v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2111.12592v2-abstract-full" style="display: none;"> We report on observations of the candidate Be/X-ray binary IGR J18219$-$1347 with \textit{Swift}/XRT, \textit{NuSTAR}, and \textit{NICER} during Type-I outbursts in March and June 2020. Our timing analysis revealed the spin period of a neutron star with $P_\textrm{spin}=52.46$ s. This periodicity, combined with the known orbital period of $72.4$ d, indicates that the system is a BeXRB. Furthermore, by comparing the infrared counterpart's spectral energy distribution to known BeXRBs, we confirm this classification and set a distance of approximately $10-15$ kpc for the source. The source's broadband X-ray spectrum ($1.5-50$ keV) is described by an absorbed power-law with photon index $螕$\,$\sim$\,$0.5$ and cutoff energy at $\sim$\,$13$ keV. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.12592v2-abstract-full').style.display = 'none'; document.getElementById('2111.12592v2-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 February, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 November, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Revised manuscript. 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/2111.09350">arXiv:2111.09350</a> <span> [<a href="https://arxiv.org/pdf/2111.09350">pdf</a>, <a href="https://arxiv.org/format/2111.09350">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1117/12.2599088">10.1117/12.2599088 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Photo-z Infrared Telescope (PIRT) -- a space instrument for rapid follow up of high-redshift gamma-ray bursts and electromagnetic counterparts to gravitational wave events </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Seiffert%2C+M">M. Seiffert</a>, <a href="/search/astro-ph?searchtype=author&query=Balady%2C+A">A. Balady</a>, <a href="/search/astro-ph?searchtype=author&query=Chang%2C+T+-">T. -C. Chang</a>, <a href="/search/astro-ph?searchtype=author&query=Dyer%2C+R">R. Dyer</a>, <a href="/search/astro-ph?searchtype=author&query=Fausey%2C+H">H. Fausey</a>, <a href="/search/astro-ph?searchtype=author&query=Guiriec%2C+S">S. Guiriec</a>, <a href="/search/astro-ph?searchtype=author&query=Hart%2C+M">M. Hart</a>, <a href="/search/astro-ph?searchtype=author&query=Morris%2C+R+O">R. O. Morris</a>, <a href="/search/astro-ph?searchtype=author&query=Rodriguez%2C+J+I">J. I. Rodriguez</a>, <a href="/search/astro-ph?searchtype=author&query=Roming%2C+P">P. Roming</a>, <a href="/search/astro-ph?searchtype=author&query=Rud%2C+M">M. Rud</a>, <a href="/search/astro-ph?searchtype=author&query=Russell%2C+D">D. Russell</a>, <a href="/search/astro-ph?searchtype=author&query=Sambruna%2C+R">R. Sambruna</a>, <a href="/search/astro-ph?searchtype=author&query=Terrile%2C+R">R. Terrile</a>, <a href="/search/astro-ph?searchtype=author&query=Torossian%2C+V">V. Torossian</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=White%2C+N+E">N. E. White</a>, <a href="/search/astro-ph?searchtype=author&query=Willems%2C+P">P. Willems</a>, <a href="/search/astro-ph?searchtype=author&query=Woodmansee%2C+A">A. Woodmansee</a>, <a href="/search/astro-ph?searchtype=author&query=Young%2C+E+T">E. T. Young</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="2111.09350v1-abstract-short" style="display: inline;"> The Photo-z InfraRed Telescope (PIRT) is an instrument on the Gamow Explorer, currently proposed for a NASA Astrophysics Medium Explorer. PIRT works in tandem with a companion wide-field instrument, the Lobster Eye X-ray Telescope (LEXT), that will identify x-ray transients likely to be associated with high redshift gamma-ray bursts (GRBs) or electromagnetic counterparts to gravitational wave (GW)… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.09350v1-abstract-full').style.display = 'inline'; document.getElementById('2111.09350v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2111.09350v1-abstract-full" style="display: none;"> The Photo-z InfraRed Telescope (PIRT) is an instrument on the Gamow Explorer, currently proposed for a NASA Astrophysics Medium Explorer. PIRT works in tandem with a companion wide-field instrument, the Lobster Eye X-ray Telescope (LEXT), that will identify x-ray transients likely to be associated with high redshift gamma-ray bursts (GRBs) or electromagnetic counterparts to gravitational wave (GW) events. After receiving an alert trigger from LEXT, the spacecraft will slew to center the PIRT field of view on the transient source. PIRT will then begin accumulating data simultaneously in five bands spanning 0.5 - 2.5 microns over a 10 arc-minute field of view. Each PIRT field will contain many hundreds of sources, only one of which is associated with the LEXT transient. PIRT will gather the necessary data in order to identify GRB sources with redshift $z > 6$, with an expected source localization better than 1 arcsec. A near real-time link to the ground will allow timely follow-up as a target of opportunity for large ground-based telescopes or the James Webb Space Telescope (JWST). PIRT will also allow localization and characterization of GW event counterparts. We discuss the instrument design, the on-board data processing approach, and the expected performance of the system. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.09350v1-abstract-full').style.display = 'none'; document.getElementById('2111.09350v1-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 November, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 5 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Proc. SPIE 11819, UV/Optical/IR Space Telescopes and Instruments: Innovative Technologies and Concepts X, 1181906 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2108.07284">arXiv:2108.07284</a> <span> [<a href="https://arxiv.org/pdf/2108.07284">pdf</a>, <a href="https://arxiv.org/format/2108.07284">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="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/10.1051/0004-6361/202140756">10.1051/0004-6361/202140756 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Sub-arcsecond imaging with the International LOFAR Telescope: II. Completion of the LOFAR Long-Baseline Calibrator Survey </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Jackson%2C+N">Neal Jackson</a>, <a href="/search/astro-ph?searchtype=author&query=Badole%2C+S">Shruti Badole</a>, <a href="/search/astro-ph?searchtype=author&query=Morgan%2C+J">John Morgan</a>, <a href="/search/astro-ph?searchtype=author&query=Chhetri%2C+R">Rajan Chhetri</a>, <a href="/search/astro-ph?searchtype=author&query=Prusis%2C+K">Kaspars Prusis</a>, <a href="/search/astro-ph?searchtype=author&query=Nikolajevs%2C+A">Atvars Nikolajevs</a>, <a href="/search/astro-ph?searchtype=author&query=Morabito%2C+L">Leah Morabito</a>, <a href="/search/astro-ph?searchtype=author&query=Brentjens%2C+M">Michiel Brentjens</a>, <a href="/search/astro-ph?searchtype=author&query=Sweijen%2C+F">Frits Sweijen</a>, <a href="/search/astro-ph?searchtype=author&query=Iacobelli%2C+M">Marco Iacobelli</a>, <a href="/search/astro-ph?searchtype=author&query=Orr%C3%B9%2C+E">Emanuela Orr霉</a>, <a href="/search/astro-ph?searchtype=author&query=Sluman%2C+J">J. Sluman</a>, <a href="/search/astro-ph?searchtype=author&query=Blaauw%2C+R">R. Blaauw</a>, <a href="/search/astro-ph?searchtype=author&query=Mulder%2C+H">H. Mulder</a>, <a href="/search/astro-ph?searchtype=author&query=van+Dijk%2C+P">P. van Dijk</a>, <a href="/search/astro-ph?searchtype=author&query=Mooney%2C+S">Sean Mooney</a>, <a href="/search/astro-ph?searchtype=author&query=Deller%2C+A">Adam Deller</a>, <a href="/search/astro-ph?searchtype=author&query=Moldon%2C+J">Javier Moldon</a>, <a href="/search/astro-ph?searchtype=author&query=Callingham%2C+J+R">J. R. Callingham</a>, <a href="/search/astro-ph?searchtype=author&query=Harwood%2C+J">Jeremy Harwood</a>, <a href="/search/astro-ph?searchtype=author&query=Hardcastle%2C+M">Martin Hardcastle</a>, <a href="/search/astro-ph?searchtype=author&query=Heald%2C+G">George Heald</a>, <a href="/search/astro-ph?searchtype=author&query=Drabent%2C+A">Alexander Drabent</a>, <a href="/search/astro-ph?searchtype=author&query=McKean%2C+J+P">J. P. McKean</a>, <a href="/search/astro-ph?searchtype=author&query=Asgekar%2C+A">A. Asgekar</a> , et al. (47 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2108.07284v1-abstract-short" style="display: inline;"> The Low-Frequency Array (LOFAR) Long-Baseline Calibrator Survey (LBCS) was conducted between 2014 and 2019 in order to obtain a set of suitable calibrators for the LOFAR array. In this paper we present the complete survey, building on the preliminary analysis published in 2016 which covered approximately half the survey area. The final catalogue consists of 30006 observations of 24713 sources in t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.07284v1-abstract-full').style.display = 'inline'; document.getElementById('2108.07284v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2108.07284v1-abstract-full" style="display: none;"> The Low-Frequency Array (LOFAR) Long-Baseline Calibrator Survey (LBCS) was conducted between 2014 and 2019 in order to obtain a set of suitable calibrators for the LOFAR array. In this paper we present the complete survey, building on the preliminary analysis published in 2016 which covered approximately half the survey area. The final catalogue consists of 30006 observations of 24713 sources in the northern sky, selected for a combination of high low-frequency radio flux density and flat spectral index using existing surveys (WENSS, NVSS, VLSS, and MSSS). Approximately one calibrator per square degree, suitable for calibration of $\geq$ 200 km baselines is identified by the detection of compact flux density, for declinations north of 30 degrees and away from the Galactic plane, with a considerably lower density south of this point due to relative difficulty in selecting flat-spectrum candidate sources in this area of the sky. Use of the VLBA calibrator list, together with statistical arguments by comparison with flux densities from lower-resolution catalogues, allow us to establish a rough flux density scale for the LBCS observations, so that LBCS statistics can be used to estimate compact flux densities on scales between 300 mas and 2 arcsec, for sources observed in the survey. The LBCS can be used to assess the structures of point sources in lower-resolution surveys, with significant reductions in the degree of coherence in these sources on scales between 2 arcsec and 300 mas. The LBCS survey sources show a greater incidence of compact flux density in quasars than in radio galaxies, consistent with unified schemes of radio sources. Comparison with samples of sources from interplanetary scintillation (IPS) studies with the Murchison Widefield Array (MWA) shows consistent patterns of detection of compact structure in sources observed both interferometrically with LOFAR and using IPS. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.07284v1-abstract-full').style.display = 'none'; document.getElementById('2108.07284v1-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 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted to a special issue of A&A on sub-arcsecond imaging with LOFAR</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 658, A2 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2108.07283">arXiv:2108.07283</a> <span> [<a href="https://arxiv.org/pdf/2108.07283">pdf</a>, <a href="https://arxiv.org/format/2108.07283">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="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/10.1051/0004-6361/202140649">10.1051/0004-6361/202140649 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Sub-arcsecond imaging with the International LOFAR Telescope I. Foundational calibration strategy and pipeline </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Morabito%2C+L+K">L. K. Morabito</a>, <a href="/search/astro-ph?searchtype=author&query=Jackson%2C+N+J">N. J. Jackson</a>, <a href="/search/astro-ph?searchtype=author&query=Mooney%2C+S">S. Mooney</a>, <a href="/search/astro-ph?searchtype=author&query=Sweijen%2C+F">F. Sweijen</a>, <a href="/search/astro-ph?searchtype=author&query=Badole%2C+S">S. Badole</a>, <a href="/search/astro-ph?searchtype=author&query=Kukreti%2C+P">P. Kukreti</a>, <a href="/search/astro-ph?searchtype=author&query=Venkattu%2C+D">D. Venkattu</a>, <a href="/search/astro-ph?searchtype=author&query=Groeneveld%2C+C">C. Groeneveld</a>, <a href="/search/astro-ph?searchtype=author&query=Kappes%2C+A">A. Kappes</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnassieux%2C+E">E. Bonnassieux</a>, <a href="/search/astro-ph?searchtype=author&query=Drabent%2C+A">A. Drabent</a>, <a href="/search/astro-ph?searchtype=author&query=Iacobelli%2C+M">M. Iacobelli</a>, <a href="/search/astro-ph?searchtype=author&query=Croston%2C+J+H">J. H. Croston</a>, <a href="/search/astro-ph?searchtype=author&query=Best%2C+P+N">P. N. Best</a>, <a href="/search/astro-ph?searchtype=author&query=Bondi%2C+M">M. Bondi</a>, <a href="/search/astro-ph?searchtype=author&query=Callingham%2C+J+R">J. R. Callingham</a>, <a href="/search/astro-ph?searchtype=author&query=Conway%2C+J+E">J. E. Conway</a>, <a href="/search/astro-ph?searchtype=author&query=Deller%2C+A+T">A. T. Deller</a>, <a href="/search/astro-ph?searchtype=author&query=Hardcastle%2C+M+J">M. J. Hardcastle</a>, <a href="/search/astro-ph?searchtype=author&query=McKean%2C+J+P">J. P. McKean</a>, <a href="/search/astro-ph?searchtype=author&query=Miley%2C+G+K">G. K. Miley</a>, <a href="/search/astro-ph?searchtype=author&query=Moldon%2C+J">J. Moldon</a>, <a href="/search/astro-ph?searchtype=author&query=R%C3%B6ttgering%2C+H+J+A">H. J. A. R枚ttgering</a>, <a href="/search/astro-ph?searchtype=author&query=Tasse%2C+C">C. Tasse</a>, <a href="/search/astro-ph?searchtype=author&query=Shimwell%2C+T+W">T. W. Shimwell</a> , et al. (49 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2108.07283v1-abstract-short" style="display: inline;"> [abridged] The International LOFAR Telescope is an interferometer with stations spread across Europe. With baselines of up to ~2,000 km, LOFAR has the unique capability of achieving sub-arcsecond resolution at frequencies below 200 MHz, although this is technically and logistically challenging. Here we present a calibration strategy that builds on previous high-resolution work with LOFAR. We give… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.07283v1-abstract-full').style.display = 'inline'; document.getElementById('2108.07283v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2108.07283v1-abstract-full" style="display: none;"> [abridged] The International LOFAR Telescope is an interferometer with stations spread across Europe. With baselines of up to ~2,000 km, LOFAR has the unique capability of achieving sub-arcsecond resolution at frequencies below 200 MHz, although this is technically and logistically challenging. Here we present a calibration strategy that builds on previous high-resolution work with LOFAR. We give an overview of the calibration strategy and discuss the special challenges inherent to enacting high-resolution imaging with LOFAR, and describe the pipeline, which is publicly available, in detail. We demonstrate the calibration strategy by using the pipeline on P205+55, a typical LOFAR Two-metre Sky Survey (LoTSS) pointing. We perform in-field delay calibration, solution referencing to other calibrators, self-calibration, and imaging of example directions of interest in the field. For this specific field and these ionospheric conditions, dispersive delay solutions can be transferred between calibrators up to ~1.5 degrees away, while phase solution transferral works well over 1 degree. We demonstrate a check of the astrometry and flux density scale. Imaging in 17 directions, the restoring beam is typically 0.3" x 0.2" although this varies slightly over the entire 5 square degree field of view. We achieve ~80 to 300 $渭$Jy/bm image rms noise, which is dependent on the distance from the phase centre; typical values are ~90 $渭$Jy/bm for the 8 hour observation with 48 MHz of bandwidth. Seventy percent of processed sources are detected, and from this we estimate that we should be able to image ~900 sources per LoTSS pointing. This equates to ~3 million sources in the northern sky, which LoTSS will entirely cover in the next several years. Future optimisation of the calibration strategy for efficient post-processing of LoTSS at high resolution (LoTSS-HR) makes this estimate a lower limit. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.07283v1-abstract-full').style.display = 'none'; document.getElementById('2108.07283v1-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 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted to a special issue of A&A on sub-arcsecond imaging with LOFAR. 24 pages, 16 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 658, A1 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2106.14921">arXiv:2106.14921</a> <span> [<a href="https://arxiv.org/pdf/2106.14921">pdf</a>, <a href="https://arxiv.org/format/2106.14921">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/stac246">10.1093/mnras/stac246 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Exploring the GRB population: Robust afterglow modelling </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Aksulu%2C+M+D">M. D. Aksulu</a>, <a href="/search/astro-ph?searchtype=author&query=Wijers%2C+R+A+M+J">R. A. M. J. Wijers</a>, <a href="/search/astro-ph?searchtype=author&query=van+Eerten%2C+H+J">H. J. van Eerten</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">A. J. van der Horst</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="2106.14921v2-abstract-short" style="display: inline;"> Gamma-ray bursts (GRBs) are ultra-relativistic collimated outflows, which emit synchrotron radiation throughout the entire electromagnetic spectrum when they interact with their environment. This afterglow emission enables us to probe the dynamics of relativistic blast waves, the microphysics of shock acceleration, and environments of GRBs. We perform Bayesian inference on a sample of GRB afterglo… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.14921v2-abstract-full').style.display = 'inline'; document.getElementById('2106.14921v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2106.14921v2-abstract-full" style="display: none;"> Gamma-ray bursts (GRBs) are ultra-relativistic collimated outflows, which emit synchrotron radiation throughout the entire electromagnetic spectrum when they interact with their environment. This afterglow emission enables us to probe the dynamics of relativistic blast waves, the microphysics of shock acceleration, and environments of GRBs. We perform Bayesian inference on a sample of GRB afterglow data sets consisting of 22 long GRBs and 4 short GRBs, using the afterglow model "scalefit", which is based on 2D relativistic hydrodynamic simulations. We make use of Gaussian processes to account for systematic deviations in the data sets, which allows us to obtain robust estimates for the model parameters. We present the inferred parameters for the sample of GRBs, and make comparisons between short GRBs and long GRBs in constant-density and stellar-wind-like environments. We find that in almost all respects such as energy and opening angle, short and long GRBs are statistically the same. Short GRBs however have a markedly lower prompt $纬$-ray emission efficiency than long GRBs. We also find that for long GRBs in ISM-like ambient media there is a significant anti-correlation between the fraction of thermal energy in the magnetic fields, $蔚_B$, and the beaming corrected kinetic energy. Furthermore, we find no evidence that the mass-loss rates of the progenitor stars are lower than those of typical Wolf-Rayet stars. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.14921v2-abstract-full').style.display = 'none'; document.getElementById('2106.14921v2-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 January, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 28 June, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Submitted to MNRAS. Accepted 2022 January 17. Received 2021 December 29; in original form 2021 June 28</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2106.14172">arXiv:2106.14172</a> <span> [<a href="https://arxiv.org/pdf/2106.14172">pdf</a>, <a href="https://arxiv.org/format/2106.14172">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/ac0fe7">10.3847/2041-8213/ac0fe7 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Fermi-GBM Observations of the SGR J1935+2154 Burst Forest </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kaneko%2C+Y">Yuki Kaneko</a>, <a href="/search/astro-ph?searchtype=author&query=Gogus%2C+E">Ersin Gogus</a>, <a href="/search/astro-ph?searchtype=author&query=Baring%2C+M+G">Matthew G. Baring</a>, <a href="/search/astro-ph?searchtype=author&query=Kouveliotou%2C+C">Chryssa Kouveliotou</a>, <a href="/search/astro-ph?searchtype=author&query=Lin%2C+L">Lin Lin</a>, <a href="/search/astro-ph?searchtype=author&query=Roberts%2C+O+J">Oliver J. Roberts</a>, <a href="/search/astro-ph?searchtype=author&query=van+der+Horst%2C+A+J">Alexander J. van der Horst</a>, <a href="/search/astro-ph?searchtype=author&query=Younes%2C+G">George Younes</a>, <a href="/search/astro-ph?searchtype=author&query=Keskin%2C+O">Ozge Keskin</a>, <a href="/search/astro-ph?searchtype=author&query=Coban%2C+O+F">Omer Faruk Coban</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="2106.14172v2-abstract-short" style="display: inline;"> During 2020 April and May, SGR J1935+2154 emitted hundreds of short bursts and became one of the most prolific transient magnetars. At the onset of the active bursting period, a 130 s burst "forest," which included some bursts with peculiar time profiles, were observed with the Fermi/Gamma-ray Burst Monitor (GBM). In this Letter, we present the results of time-resolved spectral analysis of this bu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.14172v2-abstract-full').style.display = 'inline'; document.getElementById('2106.14172v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2106.14172v2-abstract-full" style="display: none;"> During 2020 April and May, SGR J1935+2154 emitted hundreds of short bursts and became one of the most prolific transient magnetars. At the onset of the active bursting period, a 130 s burst "forest," which included some bursts with peculiar time profiles, were observed with the Fermi/Gamma-ray Burst Monitor (GBM). In this Letter, we present the results of time-resolved spectral analysis of this burst "forest" episode, which occurred on 2020 April 27. We identify thermal spectral components prevalent during the entire 130 s episode; high-energy maxima appear during the photon flux peaks, which are modulated by the spin period of the source. Moreover, the evolution of the $谓F_谓$ spectral hardness (represented by $E_{\rm peak}$ or blackbody temperature) within the lightcurve peaks is anti-correlated with the pulse phases extrapolated from the pulsation observed within the persistent soft X-ray emission of the source six hours later. Throughout the episode, the emitting area of the high-energy (hotter) component is 1-2 orders of magnitude smaller than that for the low-energy component. We interpret this with a geometrical viewing angle scenario, inferring that the high-energy component likely originates from a low-altitude hotspot located within closed toroidal magnetic field lines. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.14172v2-abstract-full').style.display = 'none'; document.getElementById('2106.14172v2-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, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 27 June, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">23 pages, 8 figures, 1 table (machine-readable table provided separately), Matches the published version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJL 916 (2021) L7 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2103.16961">arXiv:2103.16961</a> <span> [<a href="https://arxiv.org/pdf/2103.16961">pdf</a>, <a href="https://arxiv.org/format/2103.16961">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> </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/stw2105">10.1093/mnras/stw2105 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> LOFAR imaging of Cygnus A -- Direct detection of a turnover in the hotspot radio spectra </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=McKean%2C+J+P">J. P. McKean</a>, <a href="/search/astro-ph?searchtype=author&query=Godfrey%2C+L+E+H">L. E. H. Godfrey</a>, <a href="/search/astro-ph?searchtype=author&query=Vegetti%2C+S">S. Vegetti</a>, <a href="/search/astro-ph?searchtype=author&query=Wise%2C+M+W">M. W. Wise</a>, <a href="/search/astro-ph?searchtype=author&query=Morganti%2C+R">R. Morganti</a>, <a href="/search/astro-ph?searchtype=author&query=Hardcastle%2C+M+J">M. J. Hardcastle</a>, <a href="/search/astro-ph?searchtype=author&query=Rafferty%2C+D">D. Rafferty</a>, <a href="/search/astro-ph?searchtype=author&query=Anderson%2C+J">J. Anderson</a>, <a href="/search/astro-ph?searchtype=author&query=Avruch%2C+I+M">I. M. Avruch</a>, <a href="/search/astro-ph?searchtype=author&query=Beck%2C+R">R. Beck</a>, <a href="/search/astro-ph?searchtype=author&query=Bell%2C+M+E">M. E. Bell</a>, <a href="/search/astro-ph?searchtype=author&query=van+Bemmel%2C+I">I. van Bemmel</a>, <a href="/search/astro-ph?searchtype=author&query=Bentum%2C+M+J">M. J. Bentum</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardi%2C+G">G. Bernardi</a>, <a href="/search/astro-ph?searchtype=author&query=Best%2C+P">P. Best</a>, <a href="/search/astro-ph?searchtype=author&query=Blaauw%2C+R">R. Blaauw</a>, <a href="/search/astro-ph?searchtype=author&query=Bonafede%2C+A">A. Bonafede</a>, <a href="/search/astro-ph?searchtype=author&query=Breitling%2C+F">F. Breitling</a>, <a href="/search/astro-ph?searchtype=author&query=Broderick%2C+J+W">J. W. Broderick</a>, <a href="/search/astro-ph?searchtype=author&query=Bruggen%2C+M">M. Bruggen</a>, <a href="/search/astro-ph?searchtype=author&query=Cerrigone%2C+L">L. Cerrigone</a>, <a href="/search/astro-ph?searchtype=author&query=Ciardi%2C+B">B. Ciardi</a>, <a href="/search/astro-ph?searchtype=author&query=de+Gasperin%2C+F">F. de Gasperin</a>, <a href="/search/astro-ph?searchtype=author&query=Deller%2C+A">A. Deller</a>, <a href="/search/astro-ph?searchtype=author&query=Duscha%2C+S">S. Duscha</a> , et al. (53 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="2103.16961v1-abstract-short" style="display: inline;"> The low-frequency radio spectra of the hotspots within powerful radio galaxies can provide valuable information about the physical processes operating at the site of the jet termination. These processes are responsible for the dissipation of jet kinetic energy, particle acceleration, and magnetic-field generation. Here we report new observations of the powerful radio galaxy Cygnus A using the Low… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2103.16961v1-abstract-full').style.display = 'inline'; document.getElementById('2103.16961v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2103.16961v1-abstract-full" style="display: none;"> The low-frequency radio spectra of the hotspots within powerful radio galaxies can provide valuable information about the physical processes operating at the site of the jet termination. These processes are responsible for the dissipation of jet kinetic energy, particle acceleration, and magnetic-field generation. Here we report new observations of the powerful radio galaxy Cygnus A using the Low Frequency Array (LOFAR) between 109 and 183 MHz, at an angular resolution of ~3.5 arcsec. The radio emission of the lobes is found to have a complex spectral index distribution, with a spectral steepening found towards the centre of the source. For the first time, a turnover in the radio spectrum of the two main hotspots of Cygnus A has been directly observed. By combining our LOFAR imaging with data from the Very Large Array at higher frequencies, we show that the very rapid turnover in the hotspot spectra cannot be explained by a low-energy cut-off in the electron energy distribution, as has been previously suggested. Thermal (free-free) absorption or synchrotron self absorption models are able to describe the low-frequency spectral shape of the hotspots, however, as with previous studies, we find that the implied model parameters are unlikely, and interpreting the spectra of the hotspots remains problematic. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2103.16961v1-abstract-full').style.display = 'none'; document.getElementById('2103.16961v1-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 March, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 3 figures, accepted for publication in MNRAS</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> MNRAS, 463, 3143 (2016) </p> </li> </ol> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=van+der+Horst%2C+A+J&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=van+der+Horst%2C+A+J&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=van+der+Horst%2C+A+J&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> <li> <a href="/search/?searchtype=author&query=van+der+Horst%2C+A+J&start=100" class="pagination-link " aria-label="Page 3" aria-current="page">3 </a> </li> <li> <a href="/search/?searchtype=author&query=van+der+Horst%2C+A+J&start=150" class="pagination-link " 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