TY - JOUR
T1 - Jet-cocoon geometry in the optically dark, very high energy gamma-ray burst 201216C
AU - Rhodes, L.
AU - van der Horst, A. J.
AU - Fender, R.
AU - Aguilera-Dena, D. R.
AU - Bright, J. S.
AU - Vergani, S.
AU - Williams, D. R. A.
N1 - Funding Information:
The authors thank the referee for their helpful comments. LR acknowledges the support given by the Science and Technology Facilities Council through an STFC studentship. DRA-D is sup- ported by the Stavros Niarchos Foundation (SNF) and the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the 2 nd Call of 'Science and Society' Action Al w ays strive for excellence - 'Theodoros Papazoglou' (Project Number: 01431). This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. The MeerKAT telescope is operated by the South African Radio Astronomy Observatory, which is a facility of the National Research F oundation, an agenc y of the Department of Science and Innovation. e -MERLIN is a National Facility operated by the University of Manchester at Jodrell Bank Observatory on behalf of STFC, part of UK Research and Innovation.
Publisher Copyright:
© 2022 2022. The Author(s).
PY - 2022/6/1
Y1 - 2022/6/1
N2 - 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, >100 GeV) emission by MAGIC makes this the fifth VHE GRB at the 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 multicomponent model, we estimate that the optical, X-ray, and higher frequency radio data before ~25 d originates from an ultrarelativistic jet with an isotropic equivalent kinetic energy of (0.6-10) × 1052 erg and an opening angle of ~1-9°. 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) × 1048 erg. The energies of the two components are comparable to those derived in simulations of such scenarios....
AB - 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, >100 GeV) emission by MAGIC makes this the fifth VHE GRB at the 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 multicomponent model, we estimate that the optical, X-ray, and higher frequency radio data before ~25 d originates from an ultrarelativistic jet with an isotropic equivalent kinetic energy of (0.6-10) × 1052 erg and an opening angle of ~1-9°. 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) × 1048 erg. The energies of the two components are comparable to those derived in simulations of such scenarios....
KW - ISM: dust, extinction
KW - gamma-ray burst: individual: GRB 201216C
KW - radio continuum: transients
U2 - 10.1093/mnras/stac1057
DO - 10.1093/mnras/stac1057
M3 - Article
SN - 1365-2966
VL - 513
SP - 1895
EP - 1909
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 2
ER -