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J/ApJ/833/88     GRB 160509A VLA monitoring campain results     (Laskar+, 2016)

A reverse shock in GRB 160509A. Laskar T., Alexander K.D., Berger E., Fong W.-F., Margutti R., Shivvers I., Williams P.K.G., Kopac D., Kobayashi S., Mundell C., Gomboc A., Zheng W., Menten K.M., Graham M.L., Filippenko A.V. <Astrophys. J., 833, 88-88 (2016)> =2016ApJ...833...88L (SIMBAD/NED BibCode)
ADC_Keywords: Gamma rays ; Radio continuum Keywords: gamma-ray burst: general; gamma-ray burst: individual: GRB 160509A Abstract: We present the second multi-frequency radio detection of a reverse shock in a γ-ray burst. By combining our extensive radio observations of the Fermi-Large Area Telescope γ-ray burst 160509A at z=1.17 up to 20 days after the burst with Swift X-ray observations and ground-based optical and near-infrared data, we show that the afterglow emission comprises distinct reverse shock and forward shock contributions: the reverse shock emission dominates in the radio band at ≲10 days, while the forward shock emission dominates in the X-ray, optical, and near-infrared bands. Through multi-wavelength modeling, we determine a circumburst density of n0∼10-3cm-3, supporting our previous suggestion that a low-density circumburst environment is conducive to the production of long-lasting reverse shock radiation in the radio band. We infer the presence of a large excess X-ray absorption column, NH∼1.5x1022cm-2, and a high rest-frame optical extinction, AV∼3.4mag. We identify a jet break in the X-ray light curve at tjet∼6days, and thus derive a jet opening angle of θjet∼4°, yielding a beaming-corrected kinetic energy and radiated γ-ray energy of EK∼4x1050erg and Eγ∼1.3x1051erg (1-104keV, rest frame), respectively. Consistency arguments connecting the forward shocks and reverse shocks suggest a deceleration time of tdec∼460s∼T90, a Lorentz factor of Γ(tdec)∼330, and a reverse-shock-to-forward-shock fractional magnetic energy density ratio of RBB,RSB,FS∼8. Our study highlights the power of rapid-response radio observations in the study of the properties and dynamics of γ-ray burst ejecta. Description: GRB 160509A was discovered by the Fermi LAT on 2016 May 09 at 08:59:04.36 UTC (Longo+ 2016GCN..19403...1L). We observed the afterglow with the VLA starting at 0.36 days. We tracked the flux density of the afterglow over multiple epochs spanning 1.2-33.5GHz, using 3C48, 3C286, and 3C147 as flux and bandpass calibrators, and J2005+7752 as the gain calibrator. Our VLA observations spanning 0.36-20 days after the burst clearly reveal the presence of multiple spectral components in the radio afterglow. Objects: ------------------------------------------------------- RA (ICRS) DE Designation(s) ------------------------------------------------------- 20 47 00.9 +76 06 30 GRB 160509A = GRB 160509A ------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 37 81 GRB 160509A: Log of VLA observations
See also: J/MNRAS/397/1177 : Swift-XRT observations of GRBs (Evans+, 2009) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 7 F7.4 d Delt [0.3/20] Time since discovery Δt (1) 9- 14 F6.3 GHz Freq [1.2/37] Frequency of the observation 16- 21 F6.1 uJy Flux [43/2411] Flux density at Freq 23- 27 F5.1 uJy e_Flux [11/315] Uncertainty in Flux 29 I1 --- Det [0/1]? Detection code for Flux (2) 31- 37 A7 --- Setup VLA receiver band used
Note (1): 2016 May 09 at 08:59:04.36 UTC. Note (2): Code as follows: 1 = Detection; 0 = 3σ upper limit.
History: From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 19-Apr-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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