TY - JOUR
T1 - A Millimeter Rebrightening in GRB 210702A
AU - de Wet, Simon
AU - Laskar, Tanmoy
AU - Groot, Paul J.
AU - Barniol Duran, Rodolfo
AU - Berger, Edo
AU - Bhandari, Shivani
AU - Eftekhari, Tarraneh
AU - Guidorzi, Cristiano
AU - Kobayashi, Shiho
AU - Perley, Daniel A.
AU - Sari, Re’em
AU - Schroeder, Genevieve
N1 - Publisher Copyright: © 2024. The Author(s). Published by the American Astronomical Society.
PY - 2024/10/1
Y1 - 2024/10/1
N2 - We present X-ray to radio frequency observations of the bright long gamma-ray burst GRB 210702A. Our Atacama Large Millimeter/submillimeter Array 97.5 GHz observations show a significant rebrightening by a factor of ≈2 beginning at 8.2 days post-burst and rising to peak brightness at 18.1 days before declining again. This is the first such rebrightening seen in a millimeter afterglow light curve. A standard forward shock model in a stellar wind circumburst medium can explain most of our X-ray, optical, and millimeter observations prior to the rebrightening, but significantly overpredicts the self-absorbed radio emission, and cannot explain the millimeter rebrightening. We investigate possible explanations for the millimeter rebrightening, and find that energy injection or a reverse shock from a late-time shell collision are plausible causes. Similar to other bursts, our radio data may require alternative scenarios such as a thermal electron population or a structured jet to explain the data. Our observations demonstrate that millimeter light curves can exhibit some of the rich features more commonly seen in optical and X-ray afterglow light curves, motivating further millimeter wavelength studies of GRB afterglows.
AB - We present X-ray to radio frequency observations of the bright long gamma-ray burst GRB 210702A. Our Atacama Large Millimeter/submillimeter Array 97.5 GHz observations show a significant rebrightening by a factor of ≈2 beginning at 8.2 days post-burst and rising to peak brightness at 18.1 days before declining again. This is the first such rebrightening seen in a millimeter afterglow light curve. A standard forward shock model in a stellar wind circumburst medium can explain most of our X-ray, optical, and millimeter observations prior to the rebrightening, but significantly overpredicts the self-absorbed radio emission, and cannot explain the millimeter rebrightening. We investigate possible explanations for the millimeter rebrightening, and find that energy injection or a reverse shock from a late-time shell collision are plausible causes. Similar to other bursts, our radio data may require alternative scenarios such as a thermal electron population or a structured jet to explain the data. Our observations demonstrate that millimeter light curves can exhibit some of the rich features more commonly seen in optical and X-ray afterglow light curves, motivating further millimeter wavelength studies of GRB afterglows.
UR - http://www.scopus.com/inward/record.url?scp=85207293403&partnerID=8YFLogxK
U2 - https://doi.org/10.3847/1538-4357/ad77bb
DO - https://doi.org/10.3847/1538-4357/ad77bb
M3 - مقالة
SN - 0004-637X
VL - 974
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 279
ER -