Authors

W. Zheng, University of Michigan, Ann Arbor
R. F. Shen, University of Toronto
T. Sakamoto, NASA Goddard Space Flight Center
A. P. Beardmore, University of Leicester
M. De Pasquale, UCL Mullard Space Science Laboratory
X. F. Wu, University of Nevada, Las Vegas
J. Gorosabel, Instituto de Astrofísica de Andalucía - CSIC
Y. Urata, National Central University
S. Sugita, Nagoya University
B. Zhang, University of Nevada, Las Vegas
A. Pozanenko, Space Research Institute of the Russian Academy of Sciences
M. Nissinen, Taurus Hill Observatory
D. K. Sahu, Indian Institute of Astrophysics
M. Im, Seoul National University
T. N. Ukwatta, Michigan State University
M. Andreev, Institute of Astronomy of the Russian Academy of Sciences
E. Klunko, Institute of Solar-Terrestrial Physics SB RAS
A. Volnova, Lomonosov Moscow State University
C. W. Akerlof, University of Michigan, Ann Arbor
P. Anto, Indian Institute of Astrophysics
S. D. Barthelmy, NASA Goddard Space Flight Center
A. Breeveld, UCL Mullard Space Science Laboratory
U. Carsenty, Deutsches Zentrum fur Luft- Und Raumfahrt
S. Castillo-Carrión, Universidad de Málaga
A. J. Castro-Tirado, Instituto de Astrofísica de Andalucía - CSIC
M. M. Chester, Pennsylvania State University
C. J. Chuang, National Central University
R. Cunniffe, Instituto de Astrofísica de Andalucía - CSIC
A. De Ugarte Postigo, Niels Bohr Institutet
R. Duffard, Instituto de Astrofísica de Andalucía - CSIC
H. Flewelling, University Hawaii Institute for Astronomy
N. Gehrels, NASA Goddard Space Flight Center
T. Güver, The University of Arizona

Document Type

Article

Publication Date

6-1-2012

Abstract

We present a comprehensive analysis of a bright, long-duration (T 90 257 s) GRB 110205A at redshift z = 2.22. The optical prompt emission was detected by Swift/UVOT, ROTSE-IIIb, and BOOTES telescopes when the gamma-ray burst (GRB) was still radiating in the γ-ray band, with optical light curve showing correlation with γ-ray data. Nearly 200 s of observations were obtained simultaneously from optical, X-ray, to γ-ray (1 eV to 5MeV), which makes it one of the exceptional cases to study the broadband spectral energy distribution during the prompt emission phase. In particular, we clearly identify, for the first time, an interesting two-break energy spectrum, roughly consistent with the standard synchrotron emission model in the fast cooling regime. Shortly after prompt emission (1100s), a bright (R = 14.0) optical emission hump with very steep rise (α 5.5) was observed, which we interpret as the reverse shock (RS) emission. It is the first time that the rising phase of an RS component has been closely observed. The full optical and X-ray afterglow light curves can be interpreted within the standard reverse shock (RS) + forward shock (FS) model. In general, the high-quality prompt and afterglow data allow us to apply the standard fireball model to extract valuable information, including the radiation mechanism (synchrotron), radius of prompt emission (R GRB 3 × 1013cm), initial Lorentz factor of the outflow (Γ0 250), the composition of the ejecta (mildly magnetized), the collimation angle, and the total energy budget. © 2012. The American Astronomical Society. All rights reserved..

Publication Source (Journal or Book title)

Astrophysical Journal

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