PANCHROMATIC OBSERVATIONS OF THE TEXTBOOK GRB 110205A: CONSTRAINING PHYSICAL MECHANISMS OF PROMPT EMISSION AND AFTERGLOW

Journal Article · Fri Jun 01 04:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/751/2/90· OSTI ID:22037198

Zheng, W ^[1]; Shen, R F ^[2]; Sakamoto, T ^[3]; Beardmore, A P ^[4]; De Pasquale, M ^[5]; Wu, X F; Zhang, B ^[6]; Gorosabel, J ^[7]; Urata, Y ^[8]; Sugita, S ^[9]; Pozanenko, A ^[10]; Nissinen, M ^[11]; Sahu, D K ^[12]; Im, M ^[13]; Ukwatta, T N ^[14]; Andreev, M ^[15]; Klunko, E ^[16]; others, and

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1. Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, MI 48109 (United States)
2. Department of Astronomy and Astrophysics, University of Toronto, Toronto, Ontario M5S 3H4 (Canada)
3. Center for Research and Exploration in Space Science and Technology (CRESST), NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
4. Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH (United Kingdom)
5. Mullard Space Science Laboratory, University College London, Holmbury Road, Holmbury St. Mary, Dorking RH5 6NT (United Kingdom)
6. Department of Physics and Astronomy, University of Nevada Las Vegas, Las Vegas, NV 89154 (United States)
7. Instituto de Astrofisica de Andalucia (IAA-CSIC), 18008 Granada (Spain)
8. Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan (China)
9. EcoTopia Science Institute, Nagoya University, Furo-cho, chikusa, Nagoya 464-8603 (Japan)
10. Space Research Institute (IKI), 84/32 Profsoyuznaya St., Moscow 117997 (Russian Federation)
11. Taurus Hill Observatory, Haerkaemaeentie 88, 79480 Kangaslampi (Finland)
12. CREST, Indian Institute of Astrophysics, Koramangala, Bangalore 560034 (India)
13. Center for the Exploration of the Origin of the Universe, Department of Physics and Astronomy, FPRD, Seoul National University, Shillim-dong, San 56-1, Kwanak-gu, Seoul (Korea, Republic of)
14. Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)
15. Terskol Branch of Institute of Astronomy of RAS, Kabardino-Balkaria Republic 361605 (Russian Federation)
16. Institute of Solar-Terrestrial Physics, Lermontov St., 126a, Irkutsk 664033 (Russian Federation)

We present a comprehensive analysis of a bright, long-duration (T{sub 90} {approx} 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 {gamma}-ray band, with optical light curve showing correlation with {gamma}-ray data. Nearly 200 s of observations were obtained simultaneously from optical, X-ray, to {gamma}-ray (1 eV to 5 MeV), 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 ({approx}1100 s), a bright (R = 14.0) optical emission hump with very steep rise ({alpha} {approx} 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{sub GRB} {approx} 3 Multiplication-Sign 10{sup 13} cm), initial Lorentz factor of the outflow ({Gamma}{sub 0} {approx} 250), the composition of the ejecta (mildly magnetized), the collimation angle, and the total energy budget.

• OSTI ID: 22037198
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 751; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
AFTERGLOW
ASTROPHYSICS
CORRELATIONS
COSMIC GAMMA BURSTS
ENERGY SPECTRA
EV RANGE
FIREBALL MODEL
GAMMA ASTRONOMY
MEV RANGE
PHOTON EMISSION
RED SHIFT
VISIBLE RADIATION
X RADIATION