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Title: DISCOVERY OF AN EXTRA HARD SPECTRAL COMPONENT IN THE HIGH-ENERGY AFTERGLOW EMISSION OF GRB 130427A

Abstract

The extended high-energy gamma-ray (>100 MeV) emission which occurs after prompt gamma-ray bursts (GRBs) is usually characterized by a single power-law spectrum, which has been explained as the afterglow synchrotron radiation. The afterglow inverse Compton emission has long been predicted to be able to produce a high-energy component as well, but previous observations have not clearly revealed such a signature, probably due to the small number of >10 GeV photons even for the brightest GRBs known so far. In this Letter, we report on the Fermi Large Area Telescope observations of the >100 MeV emission from the very bright and nearby GRB 130427A. We characterize the time-resolved spectra of the GeV emission from the GRB onset to the afterglow phase. By performing time-resolved spectral fits of GRB 130427A, we found strong evidence of an extra hard spectral component that exists in the extended high-energy emission of this GRB. We argue that this hard component may arise from the afterglow inverse Compton emission.

Authors:
 [1]; ; ;  [2]
  1. Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China)
  2. School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)
Publication Date:
OSTI Identifier:
22118711
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 771; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2041-8205
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AFTERGLOW; ASTROPHYSICS; COMPTON EFFECT; COSMIC GAMMA BURSTS; COSMIC PHOTONS; EMISSION SPECTRA; GAMMA ASTRONOMY; GAMMA RADIATION; GAMMA SPECTRA; GEV RANGE; HARD COMPONENT; MEV RANGE; PHOTON EMISSION; SYNCHROTRON RADIATION; TELESCOPE COUNTERS; TIME RESOLUTION

Citation Formats

Tam, Pak-Hin Thomas, Qingwen, Tang, Ruoyu, Liu, Xiangyu, Wang, and Hou Shujin, E-mail: phtam@phys.nthu.edu.tw, E-mail: xywang@nju.edu.cn. DISCOVERY OF AN EXTRA HARD SPECTRAL COMPONENT IN THE HIGH-ENERGY AFTERGLOW EMISSION OF GRB 130427A. United States: N. p., 2013. Web. doi:10.1088/2041-8205/771/1/L13.
Tam, Pak-Hin Thomas, Qingwen, Tang, Ruoyu, Liu, Xiangyu, Wang, & Hou Shujin, E-mail: phtam@phys.nthu.edu.tw, E-mail: xywang@nju.edu.cn. DISCOVERY OF AN EXTRA HARD SPECTRAL COMPONENT IN THE HIGH-ENERGY AFTERGLOW EMISSION OF GRB 130427A. United States. https://doi.org/10.1088/2041-8205/771/1/L13
Tam, Pak-Hin Thomas, Qingwen, Tang, Ruoyu, Liu, Xiangyu, Wang, and Hou Shujin, E-mail: phtam@phys.nthu.edu.tw, E-mail: xywang@nju.edu.cn. 2013. "DISCOVERY OF AN EXTRA HARD SPECTRAL COMPONENT IN THE HIGH-ENERGY AFTERGLOW EMISSION OF GRB 130427A". United States. https://doi.org/10.1088/2041-8205/771/1/L13.
@article{osti_22118711,
title = {DISCOVERY OF AN EXTRA HARD SPECTRAL COMPONENT IN THE HIGH-ENERGY AFTERGLOW EMISSION OF GRB 130427A},
author = {Tam, Pak-Hin Thomas and Qingwen, Tang and Ruoyu, Liu and Xiangyu, Wang and Hou Shujin, E-mail: phtam@phys.nthu.edu.tw, E-mail: xywang@nju.edu.cn},
abstractNote = {The extended high-energy gamma-ray (>100 MeV) emission which occurs after prompt gamma-ray bursts (GRBs) is usually characterized by a single power-law spectrum, which has been explained as the afterglow synchrotron radiation. The afterglow inverse Compton emission has long been predicted to be able to produce a high-energy component as well, but previous observations have not clearly revealed such a signature, probably due to the small number of >10 GeV photons even for the brightest GRBs known so far. In this Letter, we report on the Fermi Large Area Telescope observations of the >100 MeV emission from the very bright and nearby GRB 130427A. We characterize the time-resolved spectra of the GeV emission from the GRB onset to the afterglow phase. By performing time-resolved spectral fits of GRB 130427A, we found strong evidence of an extra hard spectral component that exists in the extended high-energy emission of this GRB. We argue that this hard component may arise from the afterglow inverse Compton emission.},
doi = {10.1088/2041-8205/771/1/L13},
url = {https://www.osti.gov/biblio/22118711}, journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 1,
volume = 771,
place = {United States},
year = {Mon Jul 01 00:00:00 EDT 2013},
month = {Mon Jul 01 00:00:00 EDT 2013}
}