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The properties of GRB 120923A at a spectroscopic redshift of z ≈ 7.8
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(2018) The properties of GRB 120923A at a spectroscopic redshift of z ≈ 7.8. The Astrophysical Journal, 865 (2). 107. doi:10.3847/1538-4357/aadba9 ISSN 0004-637X.
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Official URL: http://dx.doi.org/10.3847/1538-4357/aadba9
Abstract
Gamma-ray bursts (GRBs) are powerful probes of early stars and galaxies, during and potentially even before the era of reionization. Although the number of GRBs identified at z 6 remains small, they provide a unique window on typical star-forming galaxies at that time, and thus are complementary to deep field observations. We report the identification of the optical drop-out afterglow of Swift GRB 120923A in near-infrared Gemini-North imaging, and derive a redshift of from Very Large Telescope/X-shooter spectroscopy. At this redshift the peak 15–150 keV luminosity of the burst was 3.2 × 1052 erg s−1, and in this sense it was a rather typical long-duration GRB in terms of rest frame luminosity. This burst was close to the Swift/Burst Alert Telescope detection threshold, and the X-ray and near-infrared afterglow were also faint. We present ground- and space-based follow-up observations spanning from X-ray to radio, and find that a standard external shock model with a constant-density circumburst environment of density n ≈ 4 × 10−2 cm−3 gives a good fit to the data. The near-infrared light curve exhibits a sharp break at t ≈ 3.4 days in the observer frame which, if interpreted as being due to a jet, corresponds to an opening angle of . The beaming-corrected γ-ray energy is then erg, while the beaming-corrected kinetic energy is lower, erg, suggesting that GRB 120923A was a comparatively low kinetic energy event. We discuss the implications of this event for our understanding of the high-redshift population of GRBs and their identification.
Item Type: | Journal Article | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Subjects: | Q Science > QB Astronomy | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Library of Congress Subject Headings (LCSH): | Gamma ray bursts, Red shift | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Journal or Publication Title: | The Astrophysical Journal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Publisher: | Institute of Physics Publishing, Inc. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
ISSN: | 0004-637X | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Official Date: | 1 October 2018 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Volume: | 865 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Number: | 2 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Article Number: | 107 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
DOI: | 10.3847/1538-4357/aadba9 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Status: | Peer Reviewed | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Publication Status: | Published | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Access rights to Published version: | Restricted or Subscription Access | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Date of first compliant deposit: | 23 October 2018 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Date of first compliant Open Access: | 23 October 2018 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
RIOXX Funder/Project Grant: |
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