A Reverse Shock in GRB 160509A

Tanmoy Laskar, Kate D. Alexander, Edo Berger, Wen-fai Fong, Raffaella Margutti, Isaac Shivvers, Peter K. G. Williams, Drejc Kopac, Shiho Kobayashi, Carole Mundell, Andreja Gomboc, WeiKang Zheng, Karl M. Menten, Melissa L. Graham, Alexei V. Filippenko

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

We present the second multi-frequency radio detection of a reverse shock in a $\gamma$-ray burst. By combining our extensive radio observations of the Fermi-LAT GRB 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 $\lesssim10~$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 $n_0\approx10^{-3}~$cm$^{-3}$, 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, $N_{\rm H} \approx 1.5\times10^{22}~$cm$^{-2}$, and a high rest-frame optical extinction, $A_{\rm V}\approx3.4~$mag. We identify a jet break in the X-ray light curve at $t_{\rm jet}\approx6~$d, and thus derive a jet opening angle of $\theta_{\rm jet}\approx4~$deg, yielding a beaming-corrected kinetic energy and radiated $\gamma$-ray energy of $E_{\rm K}\approx4\times10^{50}~$erg and $E_{\gamma}\approx1.3\times10^{51}~$erg ($1$-$10^4~$keV, rest frame), respectively. Consistency arguments connecting the forward and reverse shocks suggest a deceleration time of $t_{\rm dec} \approx 460~$s$~\approx T_{90}$, a Lorentz factor of $\Gamma(t_{\rm dec})\approx330$, and a reverse shock to forward shock fractional magnetic energy density ratio of $R_{\rm B}\equiv\epsilon_{\rm B,RS}/\epsilon_{\rm B,FS}\approx8$.
Original languageEnglish
Article number88
Number of pages8
JournalAstrophysical Journal
Volume833
Issue number1
DOIs
Publication statusPublished - 8 Dec 2016

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shock
radio
erg
near infrared
kinetic energy
energy
extinction
x rays
wavelength
radio observation
deceleration
modeling
afterglows
gamma ray bursts
light curve
suggestion
bursts
radio frequencies
flux density
gamma rays

Keywords

  • astro-ph.HE

Cite this

Laskar, T., Alexander, K. D., Berger, E., Fong, W., Margutti, R., Shivvers, I., ... Filippenko, A. V. (2016). A Reverse Shock in GRB 160509A. Astrophysical Journal, 833(1), [88]. https://doi.org/10.3847/1538-4357/833/1/88

A Reverse Shock in GRB 160509A. / Laskar, Tanmoy; Alexander, Kate D.; Berger, Edo; Fong, Wen-fai; Margutti, Raffaella; Shivvers, Isaac; Williams, Peter K. G.; Kopac, Drejc; Kobayashi, Shiho; Mundell, Carole; Gomboc, Andreja; Zheng, WeiKang; Menten, Karl M.; Graham, Melissa L.; Filippenko, Alexei V.

In: Astrophysical Journal, Vol. 833, No. 1, 88, 08.12.2016.

Research output: Contribution to journalArticle

Laskar, T, Alexander, KD, Berger, E, Fong, W, Margutti, R, Shivvers, I, Williams, PKG, Kopac, D, Kobayashi, S, Mundell, C, Gomboc, A, Zheng, W, Menten, KM, Graham, ML & Filippenko, AV 2016, 'A Reverse Shock in GRB 160509A', Astrophysical Journal, vol. 833, no. 1, 88. https://doi.org/10.3847/1538-4357/833/1/88
Laskar T, Alexander KD, Berger E, Fong W, Margutti R, Shivvers I et al. A Reverse Shock in GRB 160509A. Astrophysical Journal. 2016 Dec 8;833(1). 88. https://doi.org/10.3847/1538-4357/833/1/88
Laskar, Tanmoy ; Alexander, Kate D. ; Berger, Edo ; Fong, Wen-fai ; Margutti, Raffaella ; Shivvers, Isaac ; Williams, Peter K. G. ; Kopac, Drejc ; Kobayashi, Shiho ; Mundell, Carole ; Gomboc, Andreja ; Zheng, WeiKang ; Menten, Karl M. ; Graham, Melissa L. ; Filippenko, Alexei V. / A Reverse Shock in GRB 160509A. In: Astrophysical Journal. 2016 ; Vol. 833, No. 1.
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AU - Shivvers, Isaac

AU - Williams, Peter K. G.

AU - Kopac, Drejc

AU - Kobayashi, Shiho

AU - Mundell, Carole

AU - Gomboc, Andreja

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