VLBI observations of GRB 201015A, a relatively faint GRB with a hint of very high-energy gamma-ray emission

Context. A total of four long-duration gamma-ray bursts (GRBs) have been confirmed at very high-energy (≥100GeV) with high significance, and any possible peculiarities of these bursts will become clearer as the number of detected events increases. Multi-wavelength follow-up campaigns are required to...

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Autores: Giarratana, S., Rhodes, L., Marcote, B., Fender, R., Ghirlanda, G., Giroletti, M., Nava, L., Paredes i Poy, Josep Maria, Ravasio, M. E., Ribó Gomis, Marc, Patel, M., Rastinejad, J., Schroeder, G., Fong, W., Gompertz, B. P., Levan, A. J., O'Brien, P.
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2022
País:España
Institución:Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya)
Repositorio:Recercat. Dipósit de la Recerca de Catalunya
OAI Identifier:oai:recercat.cat:2445/219731
Acceso en línea:https://hdl.handle.net/2445/219731
Access Level:acceso abierto
Palabra clave:Astrofísica
Esclat de raigs gamma
Astrophysics
Gamma ray bursts
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spelling VLBI observations of GRB 201015A, a relatively faint GRB with a hint of very high-energy gamma-ray emissionGiarratana, S.Rhodes, L.Marcote, B.Fender, R.Ghirlanda, G.Giroletti, M.Nava, L.Paredes i Poy, Josep MariaRavasio, M. E.Ribó Gomis, MarcPatel, M.Rastinejad, J.Schroeder, G.Fong, W.Gompertz, B. P.Levan, A. J.O'Brien, P.AstrofísicaEsclat de raigs gammaAstrophysicsGamma ray burstsContext. A total of four long-duration gamma-ray bursts (GRBs) have been confirmed at very high-energy (≥100GeV) with high significance, and any possible peculiarities of these bursts will become clearer as the number of detected events increases. Multi-wavelength follow-up campaigns are required to extract information on the physical conditions within the jets that lead to the very high-energy counterpart, hence they are crucial to reveal the properties of this class of bursts. Aims. GRB 201015A is a long-duration GRB detected using the MAGIC telescopes from ~40 s after the burst. If confirmed, this would be the fifth and least luminous GRB ever detected at these energies. The goal of this work is to constrain the global and microphysical parameters of its afterglow phase, and to discuss the main properties of this burst in a broader context. Methods. Since the radio band, together with frequent optical and X-ray observations, proved to be a fundamental tool for overcoming the degeneracy in the afterglow modelling, we performed a radio follow-up of GRB 201015A over 12 different epochs, from 1.4 days (2020 October 17) to 117 days (2021 February 9) post-burst, with the Karl G. Jansky Very Large Array, e-MERLIN, and the European VLBI Network. We include optical and X-ray observations, performed respectively with the Multiple Mirror Telescope and the Chandra X-ray Observatory, together with publicly available data, in order to build multi-wavelength light curves and to compare them with the standard fireball model. Results. We detected a point-like transient, consistent with the position of GRB 201015A until 23 and 47 days post-burst at 1.5 and 5 GHz, respectively. No emission was detected in subsequent radio observations. The source was also detected in optical (1.4 and 2.2 days post-burst) and in X-ray (8.4 and 13.6 days post-burst) observations. Conclusions. The multi-wavelength afterglow light curves can be explained with the standard model for a GRB seen on-axis, which expands and decelerates into a medium with a homogeneous density. A circumburst medium with a wind-like profile is disfavoured. Notwithstanding the high resolution provided by the VLBI, we could not pinpoint any expansion or centroid displacement of the outflow. If the GRB is seen at the viewing angle θ that maximises the apparent velocity βapp (i.e. θ ~ βapp-1), we estimate that the Lorentz factor for the possible proper motion is Гα ≤ 40 in right ascension and Гδ ≤ 61 in declination. On the other hand, if the GRB is seen on-axis, the size of the afterglow is ≤5pc and ≤16pc at 25 and 47 days. Finally, the early peak in the optical light curve suggests the presence of a reverse shock component before 0.01 days from the burst.EDP Sciences2025202520222025info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersion11 p.application/pdfhttps://hdl.handle.net/2445/219731Articles publicats en revistes (Física Quàntica i Astrofísica)reponame:Recercat. Dipósit de la Recerca de Catalunyainstname:Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya)InglésReproducció del document publicat a: https://doi.org/10.1051/0004-6361/202142919Astronomy & Astrophysics, 2022, vol. 664, p. 1-11https://doi.org/10.1051/0004-6361/202142919(c) The European Southern Observatory (ESO), 2022info:eu-repo/semantics/openAccessoai:recercat.cat:2445/2197312026-05-29T05:05:01Z
dc.title.none.fl_str_mv VLBI observations of GRB 201015A, a relatively faint GRB with a hint of very high-energy gamma-ray emission
title VLBI observations of GRB 201015A, a relatively faint GRB with a hint of very high-energy gamma-ray emission
spellingShingle VLBI observations of GRB 201015A, a relatively faint GRB with a hint of very high-energy gamma-ray emission
Giarratana, S.
Astrofísica
Esclat de raigs gamma
Astrophysics
Gamma ray bursts
title_short VLBI observations of GRB 201015A, a relatively faint GRB with a hint of very high-energy gamma-ray emission
title_full VLBI observations of GRB 201015A, a relatively faint GRB with a hint of very high-energy gamma-ray emission
title_fullStr VLBI observations of GRB 201015A, a relatively faint GRB with a hint of very high-energy gamma-ray emission
title_full_unstemmed VLBI observations of GRB 201015A, a relatively faint GRB with a hint of very high-energy gamma-ray emission
title_sort VLBI observations of GRB 201015A, a relatively faint GRB with a hint of very high-energy gamma-ray emission
dc.creator.none.fl_str_mv Giarratana, S.
Rhodes, L.
Marcote, B.
Fender, R.
Ghirlanda, G.
Giroletti, M.
Nava, L.
Paredes i Poy, Josep Maria
Ravasio, M. E.
Ribó Gomis, Marc
Patel, M.
Rastinejad, J.
Schroeder, G.
Fong, W.
Gompertz, B. P.
Levan, A. J.
O'Brien, P.
author Giarratana, S.
author_facet Giarratana, S.
Rhodes, L.
Marcote, B.
Fender, R.
Ghirlanda, G.
Giroletti, M.
Nava, L.
Paredes i Poy, Josep Maria
Ravasio, M. E.
Ribó Gomis, Marc
Patel, M.
Rastinejad, J.
Schroeder, G.
Fong, W.
Gompertz, B. P.
Levan, A. J.
O'Brien, P.
author_role author
author2 Rhodes, L.
Marcote, B.
Fender, R.
Ghirlanda, G.
Giroletti, M.
Nava, L.
Paredes i Poy, Josep Maria
Ravasio, M. E.
Ribó Gomis, Marc
Patel, M.
Rastinejad, J.
Schroeder, G.
Fong, W.
Gompertz, B. P.
Levan, A. J.
O'Brien, P.
author2_role author
author
author
author
author
author
author
author
author
author
author
author
author
author
author
author
dc.subject.none.fl_str_mv Astrofísica
Esclat de raigs gamma
Astrophysics
Gamma ray bursts
topic Astrofísica
Esclat de raigs gamma
Astrophysics
Gamma ray bursts
description Context. A total of four long-duration gamma-ray bursts (GRBs) have been confirmed at very high-energy (≥100GeV) with high significance, and any possible peculiarities of these bursts will become clearer as the number of detected events increases. Multi-wavelength follow-up campaigns are required to extract information on the physical conditions within the jets that lead to the very high-energy counterpart, hence they are crucial to reveal the properties of this class of bursts. Aims. GRB 201015A is a long-duration GRB detected using the MAGIC telescopes from ~40 s after the burst. If confirmed, this would be the fifth and least luminous GRB ever detected at these energies. The goal of this work is to constrain the global and microphysical parameters of its afterglow phase, and to discuss the main properties of this burst in a broader context. Methods. Since the radio band, together with frequent optical and X-ray observations, proved to be a fundamental tool for overcoming the degeneracy in the afterglow modelling, we performed a radio follow-up of GRB 201015A over 12 different epochs, from 1.4 days (2020 October 17) to 117 days (2021 February 9) post-burst, with the Karl G. Jansky Very Large Array, e-MERLIN, and the European VLBI Network. We include optical and X-ray observations, performed respectively with the Multiple Mirror Telescope and the Chandra X-ray Observatory, together with publicly available data, in order to build multi-wavelength light curves and to compare them with the standard fireball model. Results. We detected a point-like transient, consistent with the position of GRB 201015A until 23 and 47 days post-burst at 1.5 and 5 GHz, respectively. No emission was detected in subsequent radio observations. The source was also detected in optical (1.4 and 2.2 days post-burst) and in X-ray (8.4 and 13.6 days post-burst) observations. Conclusions. The multi-wavelength afterglow light curves can be explained with the standard model for a GRB seen on-axis, which expands and decelerates into a medium with a homogeneous density. A circumburst medium with a wind-like profile is disfavoured. Notwithstanding the high resolution provided by the VLBI, we could not pinpoint any expansion or centroid displacement of the outflow. If the GRB is seen at the viewing angle θ that maximises the apparent velocity βapp (i.e. θ ~ βapp-1), we estimate that the Lorentz factor for the possible proper motion is Гα ≤ 40 in right ascension and Гδ ≤ 61 in declination. On the other hand, if the GRB is seen on-axis, the size of the afterglow is ≤5pc and ≤16pc at 25 and 47 days. Finally, the early peak in the optical light curve suggests the presence of a reverse shock component before 0.01 days from the burst.
publishDate 2022
dc.date.none.fl_str_mv 2022
2025
2025
2025
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv https://hdl.handle.net/2445/219731
url https://hdl.handle.net/2445/219731
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv Reproducció del document publicat a: https://doi.org/10.1051/0004-6361/202142919
Astronomy & Astrophysics, 2022, vol. 664, p. 1-11
https://doi.org/10.1051/0004-6361/202142919
dc.rights.none.fl_str_mv (c) The European Southern Observatory (ESO), 2022
info:eu-repo/semantics/openAccess
rights_invalid_str_mv (c) The European Southern Observatory (ESO), 2022
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv 11 p.
application/pdf
dc.publisher.none.fl_str_mv EDP Sciences
publisher.none.fl_str_mv EDP Sciences
dc.source.none.fl_str_mv Articles publicats en revistes (Física Quàntica i Astrofísica)
reponame:Recercat. Dipósit de la Recerca de Catalunya
instname:Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya)
instname_str Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya)
reponame_str Recercat. Dipósit de la Recerca de Catalunya
collection Recercat. Dipósit de la Recerca de Catalunya
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15,811543

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