J/ApJ/884/121 Radio to UV observations of GRB 181201A (Laskar+, 2019)
A reverse shock in GRB 181201A.
Laskar T., van Eerten H., Schady P., Mundell C.G., Alexander K.D.,
Barniol Duran R., Berger E., Bolmer J., Chornock R., Coppejans D.L.,
Fong W.-F., Gomboc A., Jordana-Mitjans N., Kobayashi S., Margutti R.,
Menten K.M., Sari R., Yamazaki R., Lipunov V.M., Gorbovskoy E.,
Kornilov V.G., Tyurina N., Zimnukhov D., Podesta R., Levato H.,
Buckley D.A.H., Tlatov A., Rebolo R., Serra-Ricart M.
<Astrophys. J., 884, 121 (2019)>
=2019ApJ...884..121L 2019ApJ...884..121L
ADC_Keywords: GRB; Photometry, ultraviolet; Photometry, ugriz; Radio sources
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
FS synchrotron emission. We uncover and account for all discovered
degeneracies in the model parameters. The joint RS-FS modeling reveals
a weakly magnetized (σ∼3x10-3), mildly relativistic RS, from
which we derive an initial bulk Lorentz factor of Γ0∼103 for
the GRB jet. Our results support the hypothesis that low-density
environments are conducive to the observability of RS emission. We
compare our observations to other events with strong RS detections and
find a likely observational bias selecting for longer lasting,
nonrelativistic RSs. We present and begin to address new challenges in
modeling posed by the present generation of comprehensive,
multifrequency data sets.
Description:
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 2018GCN.23469....1M).
The optical afterglow was discovered in MASTER
(Lipunov+ 2010AdAst2010E..30L 2010AdAst2010E..30L) Global Robotic Net observations
(Podesta+ 2018GCN.23470....1P 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.
Objects:
-------------------------------------------------------
RA (ICRS) DE Designation(s)
-------------------------------------------------------
21 17 11.20 -12 37 50.9 GRB 181201A = GRB 181201A
-------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 32 41 Swift UVOT observations of GRB 181201A
table2.dat 113 121 Optical and Near-IR observations of GRB 181201A
table3.dat 34 95 Radio and millimeter observations of GRB 181201A
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See also:
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)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 F6.4 d Delt [0.17/8.76] Mid-time of the observation
since burst (2018 December 1 at 02:38 UT)
8- 10 A3 --- Band Swift/UVOT band used
12- 20 E9.3 mJy Flux [0.0044/0.62] Flux density in Band
22- 30 E9.3 mJy e_Flux [0.001/0.06] Uncertainty in Flux
32 I1 --- Det [0/1] Dectection; 1 = yes
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 E10.4 d Delt [0.0018/23.11] Mid-time of the observation
since burst (2018 December 1 at 02:38 UT)
12- 28 A17 --- Obs Observatory identifier
30- 39 A10 --- Inst Instrument identifier
41- 42 A2 --- Filt Filter used
44- 51 E8.2 Hz Freq [137000000000000/688000000000000] Frequency
of Filt
53- 61 E9.3 mJy Flux [0.0067/28.55] Flux density in Filt
63- 71 E9.3 mJy e_Flux [0.00018/0.16] Uncertainty in Flux
73 I1 --- Det [0/1] Dectection; 1 = yes
75-113 A39 --- Ref Reference
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- Obs Observatory identifier (ALMA, GMRT or VLA)
6- 10 F5.2 GHz Freq [0.6/97.5] Frequency
12- 20 E9.3 d Time [0.88/163.5] Time since burst
(2018 December 1 at 02:38 UT)
22- 26 F5.3 mJy Flux [0.16/3.42] Flux density from Obs
28- 32 F5.3 mJy e_Flux [0.014/0.6] Uncertainty in Flux
34 I1 --- Det [0/1] Dectection; 1 = yes
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 24-Mar-2021