GRB 090902B: AFTERGLOW OBSERVATIONS AND IMPLICATIONS

Journal Article · Sat May 01 00:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/714/1/799· OSTI ID:21448890

Pandey, S B; Akerlof, C; McKay, T A ^[1]; Swenson, C A ^[2]; Perley, D A; Kleiser, I K. W. ^[3]; Guidorzi, C ^[4]; Wiersema, K ^[5]; Malesani, D ^[6]; Ashley, M C. B. ^[7]; Bersier, D; Cano, Z; Kobayashi, S; Melandri, A; Mottram, C J ^[8]; Gomboc, A ^[9]; Ilyin, I ^[10]; Jakobsson, P ^[11]; Kouveliotou, C ^[12]; Levan, A J ^[13]

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1. Randall Laboratory of Physics, University of Michigan, 450 Church St., Ann Arbor, MI 48109-1040 (United States)
2. Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States)
3. Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)
4. Dipartimento di Fisica, Universita di Ferrara, via Saragat 1, I-44100 Ferrara (Italy)
5. Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom)
6. Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries vej 30, DK-2100 Copenhagen Oe (Denmark)
7. School of Physics, University of New South Wales, Sydney NSW 2052 (Australia)
8. Astrophysics Research Institute, Liverpool JMU, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD (United Kingdom)
9. Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana (Slovenia)
10. Astrophysikalisches Institut Potsdam, An der Sternwarte 16, D-14482 Potsdam (Germany)
11. Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, IS-107 ReykjavIk (Iceland)
12. NASA, Marshall Space Flight Center, NSSTC, 320 Sparkman Drive, Huntsville, Alabama 35805 (United States)
13. Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)

The optical-infrared afterglow of the Large Area Telescope (LAT)-detected long-duration burst, GRB 090902B, has been observed by several instruments. The earliest detection by ROTSE-IIIa occurred 80 minutes after detection by the Gamma-ray Burst Monitor instrument on board the Fermi Gamma-Ray Space Telescope, revealing a bright afterglow and a decay slope suggestive of a reverse shock origin. Subsequent optical-IR observations followed the light curve for 6.5 days. The temporal and spectral behavior at optical-infrared frequencies is consistent with synchrotron fireball model predictions; the cooling break lies between optical and XRT frequencies {approx}1.9 days after the burst. The inferred electron energy index is p = 1.8 {+-} 0.2, which would however imply an X-ray decay slope flatter than observed. The XRT and LAT data have similar spectral indices and the observed steeper value of the LAT temporal index is marginally consistent with the predicted temporal decay in the radiative regime of the forward shock model. Absence of a jet break during the first 6 days implies a collimation-corrected {gamma}-ray energy E{sub {gamma}} > 2.2 x 10{sup 52} erg, one of the highest ever seen in a long-duration gamma-ray bursts. More events combining GeV photon emission with multiwavelength observations will be required to constrain the nature of the central engine powering these energetic explosions and to explore the correlations between energetic quanta and afterglow emission.

• OSTI ID: 21448890
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 714; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
AFTERGLOW
COSMIC GAMMA BURSTS
COSMIC RADIATION
EMISSION
EXPLOSIONS
FIREBALL MODEL
IONIZING RADIATIONS
MATHEMATICAL MODELS
PARTICLE MODELS
PHOTON EMISSION
PRIMARY COSMIC RADIATION
RADIATIONS
TELESCOPES