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Title: INVERSE COMPTON EMISSION FROM THE PROMPT OPTICAL EMISSION REGION IN GAMMA-RAY BURSTS

Abstract

Prompt optical emission accompanying gamma-ray emission has been detected in several gamma-ray bursts (GRBs), and its origin is still under debate. A plausible interpretation is that the prompt optical emission is generated by internal shocks but from regions different from the prompt gamma-ray one. Based on this model, we investigate in detail the inverse Compton (IC) emission including the synchrotron self-Compton (SSC) and second inverse Compton (2IC) ones from the optical emission region. We expect that this study could provide a clue to the origin of prompt optical emission. We first explore the dependence of IC Y factor on some uncertain parameters such as the magnetic field equipartition factor and the Lorentz factor of GRB ejecta. The results indicate that the 2IC emission associated with strong optical flashes (such as GRB 080319b) may be easily detected by Fermi for general parameters. If the SSC peak energy is in the range of tens-to-hundreds keV but generally much weaker than the prompt gamma-ray emission, the component may be detectable by Swift (BAT). For moderately bright optical flashes, the 2IC emission is marginally detectable while the SSC is not. For weak optical flashes, both the 2IC and SSC components are undetectable. We thenmore » carry out a numerical calculation of the expected spectrum including synchrotron, SSC, and the 2IC emission for various parameters, which verifies the analytical results. Finally, taking GRB 080319b as an example, we make a simple case study. We find that the detection of the 2IC emission optical region by Fermi is promising. The future simultaneous detection of optical and high energy (MeV-GeV) from the emissions will possibly reveal the nature of the prompt optical emission and allow us to measure the quantities presently unknown such as the bulk Lorentz factor, radiative electrons energy, and magnetic field.« less

Authors:
; ;  [1];  [2]
  1. Department of Astronomy, Nanjing University, Nanjing 210093 (China)
  2. National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, P.O. Box 110, 650011 Kunming (China)
Publication Date:
OSTI Identifier:
21392372
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 708; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/708/2/1357; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COSMIC GAMMA BURSTS; ELECTRONS; GEV RANGE; KEV RANGE; MAGNETIC FIELDS; MEV RANGE; PHOTON EMISSION; COSMIC RADIATION; ELEMENTARY PARTICLES; EMISSION; ENERGY RANGE; FERMIONS; IONIZING RADIATIONS; LEPTONS; PRIMARY COSMIC RADIATION; RADIATIONS

Citation Formats

Zhao, X H, Dai, Z G, Liu, T, Bai, J M, and Peng, Z. Y., E-mail: xhzhao@nju.edu.c, E-mail: pzy@ynao.ac.c. INVERSE COMPTON EMISSION FROM THE PROMPT OPTICAL EMISSION REGION IN GAMMA-RAY BURSTS. United States: N. p., 2010. Web. doi:10.1088/0004-637X/708/2/1357.
Zhao, X H, Dai, Z G, Liu, T, Bai, J M, & Peng, Z. Y., E-mail: xhzhao@nju.edu.c, E-mail: pzy@ynao.ac.c. INVERSE COMPTON EMISSION FROM THE PROMPT OPTICAL EMISSION REGION IN GAMMA-RAY BURSTS. United States. https://doi.org/10.1088/0004-637X/708/2/1357
Zhao, X H, Dai, Z G, Liu, T, Bai, J M, and Peng, Z. Y., E-mail: xhzhao@nju.edu.c, E-mail: pzy@ynao.ac.c. 2010. "INVERSE COMPTON EMISSION FROM THE PROMPT OPTICAL EMISSION REGION IN GAMMA-RAY BURSTS". United States. https://doi.org/10.1088/0004-637X/708/2/1357.
@article{osti_21392372,
title = {INVERSE COMPTON EMISSION FROM THE PROMPT OPTICAL EMISSION REGION IN GAMMA-RAY BURSTS},
author = {Zhao, X H and Dai, Z G and Liu, T and Bai, J M and Peng, Z. Y., E-mail: xhzhao@nju.edu.c, E-mail: pzy@ynao.ac.c},
abstractNote = {Prompt optical emission accompanying gamma-ray emission has been detected in several gamma-ray bursts (GRBs), and its origin is still under debate. A plausible interpretation is that the prompt optical emission is generated by internal shocks but from regions different from the prompt gamma-ray one. Based on this model, we investigate in detail the inverse Compton (IC) emission including the synchrotron self-Compton (SSC) and second inverse Compton (2IC) ones from the optical emission region. We expect that this study could provide a clue to the origin of prompt optical emission. We first explore the dependence of IC Y factor on some uncertain parameters such as the magnetic field equipartition factor and the Lorentz factor of GRB ejecta. The results indicate that the 2IC emission associated with strong optical flashes (such as GRB 080319b) may be easily detected by Fermi for general parameters. If the SSC peak energy is in the range of tens-to-hundreds keV but generally much weaker than the prompt gamma-ray emission, the component may be detectable by Swift (BAT). For moderately bright optical flashes, the 2IC emission is marginally detectable while the SSC is not. For weak optical flashes, both the 2IC and SSC components are undetectable. We then carry out a numerical calculation of the expected spectrum including synchrotron, SSC, and the 2IC emission for various parameters, which verifies the analytical results. Finally, taking GRB 080319b as an example, we make a simple case study. We find that the detection of the 2IC emission optical region by Fermi is promising. The future simultaneous detection of optical and high energy (MeV-GeV) from the emissions will possibly reveal the nature of the prompt optical emission and allow us to measure the quantities presently unknown such as the bulk Lorentz factor, radiative electrons energy, and magnetic field.},
doi = {10.1088/0004-637X/708/2/1357},
url = {https://www.osti.gov/biblio/21392372}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 708,
place = {United States},
year = {Sun Jan 10 00:00:00 EST 2010},
month = {Sun Jan 10 00:00:00 EST 2010}
}