主要内容:
KN会抑制高能辐射,让高能的下降更快,从而对高能的余辉外籍波模型不利。
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Title: |
| Klein-Nishina Effects on the High-energy Afterglow Emission of Gamma-ray Bursts |
Authors: |
| Wang, Xiang-Yu; He, Hao-Ning; Li, Zhuo; Wu, Xue-Feng; Dai, Zi-Gao |
Affiliation: |
| AA(Department of Astronomy, Nanjing University, Nanjing 210093, China ), AB(Department of Astronomy, Nanjing University, Nanjing 210093, China ), AC(Department of Astronomy, Peking University, Beijing 100871, China ; Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, China ), AD(Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802, USA ; Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, China), AE(Department of Astronomy, Nanjing University, Nanjing 210093, China ) |
Publication: |
| The Astrophysical Journal, Volume 712, Issue 2, pp. 1232-1240 (2010). (ApJ Homepage) |
Publication Date: |
| 04/2010 |
Origin: |
| IOP |
ApJ Keywords: |
| gamma-ray burst: general, radiation mechanisms: non-thermal |
DOI: |
| 10.1088/0004-637X/712/2/1232 |
Bibliographic Code: |
| 2010ApJ...712.1232W |
Abstract
Extended high-energy (gsim100 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 <~ 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.
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