A reverse shock in GRB 181201A. (2019)
Keywords :
Gamma-ray bursts; Astronomy data modeling; High energy astrophysics; Transient sources; Gamma-ray transient sources; Radio transient sources; X-ray transient sources; Markov chain Monte Carlo; Interstellar synchrotron emission; Shocks; Relativistic jets; Relativistic fluid dynamics
Abstract:We present comprehensive multiwavelength radio to X-ray observations of GRB 181201A spanning from ~150s to ~163days after the burst, comprising the first joint ALMA-VLA-GMRT observations of a gamma-ray burst (GRB) afterglow. The radio and millimeter-band data reveal a distinct signature at ~3.9days, which we interpret as reverse-shock (RS) emission. Our observations present the first time that a single radio- frequency spectral energy distribution can be decomposed directly into RS and forward shock (FS) components. We perform detailed modeling of the full multiwavelength data set, using Markov Chain Monte Carlo sampling to construct the joint posterior density function of the underlying physical parameters describing the RS and
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GRB181201A was discovered by the IBIS and ISGRI instruments on board
the INTEGRAL satellite on 2018 December 1 at 02:38 UT
(Mereghetti+ 2018GCN.23469....1M).
The optical afterglow was discovered in MASTER
(Lipunov+ 2010AdAst2010E..30L) Global Robotic Net observations
(Podesta+ 2018GCN.23470....1P) 10s after the INTEGRAL alert and later
by the Swift UV/optical telescope.
We derived aperture photometry from pipeline-processed UVOT images
downloaded from the Swift data center.
Four MASTER-net observatories (MASTER-Kislovodsk, MASTER-IAC,
MASTER-SAAO, and MASTER-OAFA) participated in rapid-response and
follow-up observations of GRB 181201A, beginning on 2019 December 1 in
the BVRI and Clear bands.
We observed the afterglow of GRB 181201A with the Gamma-Ray Burst
Optical/Near-Infrared Detector (GROND) on the MPI/ESO 2.2m telescope
in La Silla in Chile beginning 0.91 days after the burst in
g'r'i'z'JHK filters.
We also observed the afterglow with the Ohio State Multi-Object
Spectrograph (OSMOS) on the 2.4m Hiltner telescope at MDM Observatory
on 2018 December 4, with 120s exposures each in the BVRI bands.
We obtained two later epochs of imaging using the Templeton detector
on the 1.3m McGraw-Hill telescope on the nights of 2018 December 9 and
10, obtaining 4x300s each in r' and i' bands.
And we obtained Liverpool Telescope (LT) imaging with the
infrared/optical camera (IO:O) at ~2.7days, comprising 3x120s
exposures in g'r'i' bands.
We obtained five epochs of ALMA Band 3 (3mm) observations of
GRB181201A spanning 0.88 days to 29.8d after the burst through
program 2018.1.01454.T (PI: Laskar).
We observed the afterglow using the VLA starting 2.9days after the
burst through programs 18A-088 and 18B-407 (PI: Laskar). We detected
and tracked the flux density of the afterglow from 1.2GHz to 37GHz
over multiple epochs until ~164 days after the burst.
Finally, we observed the afterglow using the upgraded Giant Meterwave
Radio Telescope (uGMRT) through program 35_065 (PI: Laskar) starting
12.5d and 13.5d after the burst in Bands 4 (center frequency 550MHz)
and 5 (center frequency 1450MHz), respectively.
- J/ApJ/781/37 : Multi-band photometry of GRB 130427A (Perley+, 2014)
- J/ApJ/814/1 : GRB 120326A, 100418A & 100901A multi-wave. obs. (Laskar+, 2015)
- J/ApJ/833/88 : GRB 160509A VLA monitoring campain results (Laskar+, 2016)
- J/ApJ/862/94 : Multiwavelength obs. of GRB 161219B (Laskar+, 2018)
- J/ApJ/858/65 : VLA study of high-redshift GRBs. I. GRB140311A (Laskar+, 2018)
- J/ApJ/859/134 : VLA study of high-redshift GRBs. II. GRB140304A (Laskar+, 2018)
