| Title: |
A Radio Flare in the Long-lived Afterglow of the Distant Short GRB 210726A: Energy Injection or a Reverse Shock from Shell Collisions? |
| Authors: |
Schroeder, G; Rhodes, L; Laskar, T; Nugent, A; Escorial, AR; Rastinejad, JC; Fong, W; van der Horst, AJ; Veres, P; Alexander, KD; Andersson, A; Berger, E; Blanchard, PK; Chastain, S; Christensen, L; Fender, R; Green, DA; Groot, P; Heywood, I; Horesh, A; Izzo, L; Kilpatrick, CD; Körding, E; Lien, A |
| Publisher Information: |
American Astronomical Society |
| Publication Year: |
2024 |
| Collection: |
Oxford University Research Archive (ORA) |
| Description: |
We present the discovery of the radio afterglow of the short gamma-ray burst (GRB) 210726A, localized to a galaxy at a photometric redshift of z ∼ 2.4. While radio observations commenced ≲1 day after the burst, no radio emission was detected until ∼11 days. The radio afterglow subsequently brightened by a factor of ∼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 multiwavelength X-ray and radio data, and underpredicts the flux of the radio flare by a factor of ≈5. We find that the addition of substantial energy injection, which increases the isotropic kinetic energy of the burst by a factor of ≈4, or a reverse shock from a shell collision are viable solutions to match the broadband behavior. At z ∼ 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 ≲10 days after the burst, potentially missing these late-rising, luminous radio afterglows. |
| Document Type: |
article in journal/newspaper |
| Language: |
English |
| DOI: |
10.3847/1538-4357/ad49ab |
| Availability: |
https://doi.org/10.3847/1538-4357/ad49ab; https://ora.ox.ac.uk/objects/uuid:0e3ee5a6-2704-48bd-b81d-1ad473dbc164 |
| Rights: |
info:eu-repo/semantics/openAccess ; CC Attribution (CC BY) |
| Accession Number: |
edsbas.3FF6F4A |
| Database: |
BASE |