KLEIN-NISHINA EFFECTS ON THE HIGH-ENERGY AFTERGLOW EMISSION OF GAMMA-RAY BURSTS

Journal Article · Thu Apr 01 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/712/2/1232· OSTI ID:21394203

Xiangyu, Wang; Haoning, He; Zigao, Dai ^[1]; Li, Zhuo ^[2]; Xuefeng, Wu ^[3]

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1. Department of Astronomy, Nanjing University, Nanjing 210093 (China)
2. Department of Astronomy, Peking University, Beijing 100871 (China)
3. Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States)

Extended high-energy ({approx}>100 MeV) gamma-ray emission that lasts much longer than the prompt sub-MeV emission has been detected from quite a few gamma-ray bursts (GRBs) by Fermi-Large Area Telescope (LAT) recently. A plausible scenario is that this emission is the afterglow synchrotron emission produced by electrons accelerated in the forward shocks. In this scenario, the electrons that produce synchrotron high-energy emission also undergo inverse Compton (IC) loss and the IC scattering with the synchrotron photons should be in the Klein-Nishina (KN) regime. Here we study effects of the KN scattering on the high-energy synchrotron afterglow emission. We find that at early times the KN suppression effect on those electrons that produce the high-energy emission is usually strong and therefore their IC loss is small with a Compton parameter Y {approx}< a few for a wide range of parameter space. This leads to a relatively bright synchrotron afterglow at high energies that can be detected by Fermi-LAT. As the KN suppression effect weakens with time, the IC loss increases and could dominate over the synchrotron loss in some parameter spaces. This will lead to a faster temporal decay of the high-energy synchrotron emission than is predicted by the standard synchrotron model, which may explain the observed rapid decay of the early high-energy gamma-ray emission in GRB090510 and GRB090902B.

• OSTI ID: 21394203
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 712; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BOSONS
COSMIC GAMMA BURSTS
COSMIC RADIATION
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
EMISSION
ENERGY RANGE
FERMIONS
GAMMA RADIATION
IONIZING RADIATIONS
LEPTONS
MASSLESS PARTICLES
MEV RANGE
MEV RANGE 100-1000
PHOTONS
PRIMARY COSMIC RADIATION
RADIATIONS
SCATTERING
TELESCOPES