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GeV Emission from Prompt and Afterglow Phases of Gamma-Ray Bursts

Ando, Shin'ichiro and Nakar, Ehud and Sari, Re'em (2008) GeV Emission from Prompt and Afterglow Phases of Gamma-Ray Bursts. Astrophysical Journal, 689 (2). pp. 1150-1160. ISSN 0004-637X. doi:10.1086/592486.

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We investigate the GeV emission from gamma-ray bursts (GRBs) using the results from the Energetic Gamma Ray Experimental Telescope (EGRET) and in view of the Gamma-Ray Large Area Space Telescope (GLAST). Assuming that the conventional prompt and afterglow photons originate from synchrotron radiation, we compare an accompanying inverse-Compton component with EGRET measurements and upper limits on GeV fluence, taking Klein-Nishina feedback into account. We find that the EGRET constraints are consistent with the theoretical framework of the synchrotron self-Compton model for both prompt and afterglow phases, and discuss constraints on microphysical parameters in both phases. Based on the inverse-Compton model and using EGRET results, we predict that GLAST would detect GRBs with GeV photons at a rate of ≳ 20 yr^-1 from both the prompt and afterglow phases. This rate applies to the high-energy tail of the prompt synchrotron emission and to the inverse-Compton component of the afterglow. Theory predicts that in a large fraction of the cases where synchrotron GeV prompt emission would be detected by GLAST, inverse-Compton photons should also be detected at high energies (≳ 10 GeV). Therefore, GLAST will enable a more precise test of the high-energy emission mechanism. Finally, we show that the contribution of GRBs to the flux of the extragalactic gamma-ray background measured with EGRET is at least 0.01%, and likely around 0.1%.

Item Type:Article
Related URLs:
URLURL TypeDescription
Nakar, Ehud0000-0002-4534-7089
Sari, Re'em0000-0002-1084-3656
Additional Information:© 2008 The American Astronomical Society. Received 2007 August 6; accepted 2008 August 11. We are grateful to B. L. Dingus and M. M. Gonzalez Sanchez for very helpful comments and discussions. We thank the referee for useful comments. This work was supported by the Sherman Fairchild Foundation (S. A. and E. N.), a NASA Swift Grant (E. N.), the Alfred P. Sloan Foundation, the Packard Foundation, and a NASA ATP Grant (R. S.).
Funding AgencyGrant Number
Sherman Fairchild FoundationUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
Subject Keywords:gamma rays: bursts; radiation mechanisms: nonthermal
Issue or Number:2
Record Number:CaltechAUTHORS:ANDapj08
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:13345
Deposited By: Tony Diaz
Deposited On:22 Apr 2009 22:03
Last Modified:08 Nov 2021 22:37

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