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Article: On the α-intensity correlation in gamma-ray bursts: subphotospheric heating with varying entropy

TitleOn the α-intensity correlation in gamma-ray bursts: subphotospheric heating with varying entropy
Authors
Keywordsgamma-ray burst
general
gamma-ray burst
individual
radiation mechanism
Issue Date2019
PublisherOxford University press, co-published with Royal Astronomical Society. The Journal's web site is located at http://www.oxfordjournals.org/our_journals/mnras/
Citation
Monthly Notices of the Royal Astronomical Society, 2019, v. 484 n. 2, p. 1912-1925 How to Cite?
AbstractThe emission mechanism during the prompt phase in gamma-ray bursts (GRBs) can be investigated through correlations between spectral properties. Here, we revisit the correlation relating the instantaneous flux, F, and the photon index below the spectral break, α, in individual emission pulses, by studying the 38 most prominent pulses in the Fermi/Gamma-ray Burst Monitor GRB catalogue. First, we search for signatures of the bias in the determination of α due to the limited spectral coverage (window effect) expected in the synchrotron case. The absence of such a characteristic signature argues against the simplest synchrotron models. We instead find that the observed correlation between F and α can, in general, be described by the relation F(t) ∝ e^{k α (t)}, for which the median k = 3. We suggest that this correlation is a manifestation of subphotospheric heating in a flow with a varying entropy. Around the peak of the light curve, a large entropy causes the photosphere to approach the saturation radius, leading to an intense emission with a narrow spectrum. As the entropy decreases the photosphere secedes from the saturation radius, and weaker emission with a broader spectrum is expected. This simple scenario naturally leads to a correlated variation of the intensity and spectral shape, covering the observed range.
Persistent Identifierhttp://hdl.handle.net/10722/271898
ISSN
2017 Impact Factor: 5.194
2015 SCImago Journal Rankings: 2.806

 

DC FieldValueLanguage
dc.contributor.authorRyde, F-
dc.contributor.authorYu, HF-
dc.contributor.authorDereli-Bégué, H-
dc.contributor.authorLundman, C-
dc.contributor.authorPe'er, A-
dc.contributor.authorLi, L-
dc.date.accessioned2019-07-20T10:31:38Z-
dc.date.available2019-07-20T10:31:38Z-
dc.date.issued2019-
dc.identifier.citationMonthly Notices of the Royal Astronomical Society, 2019, v. 484 n. 2, p. 1912-1925-
dc.identifier.issn0035-8711-
dc.identifier.urihttp://hdl.handle.net/10722/271898-
dc.description.abstractThe emission mechanism during the prompt phase in gamma-ray bursts (GRBs) can be investigated through correlations between spectral properties. Here, we revisit the correlation relating the instantaneous flux, F, and the photon index below the spectral break, α, in individual emission pulses, by studying the 38 most prominent pulses in the Fermi/Gamma-ray Burst Monitor GRB catalogue. First, we search for signatures of the bias in the determination of α due to the limited spectral coverage (window effect) expected in the synchrotron case. The absence of such a characteristic signature argues against the simplest synchrotron models. We instead find that the observed correlation between F and α can, in general, be described by the relation F(t) ∝ e^{k α (t)}, for which the median k = 3. We suggest that this correlation is a manifestation of subphotospheric heating in a flow with a varying entropy. Around the peak of the light curve, a large entropy causes the photosphere to approach the saturation radius, leading to an intense emission with a narrow spectrum. As the entropy decreases the photosphere secedes from the saturation radius, and weaker emission with a broader spectrum is expected. This simple scenario naturally leads to a correlated variation of the intensity and spectral shape, covering the observed range.-
dc.languageeng-
dc.publisherOxford University press, co-published with Royal Astronomical Society. The Journal's web site is located at http://www.oxfordjournals.org/our_journals/mnras/-
dc.relation.ispartofMonthly Notices of the Royal Astronomical Society-
dc.rightsMonthly Notices of the Royal Astronomical Society. Copyright © Oxford University press, co-published with Royal Astronomical Society.-
dc.rightsThis article has been accepted for publication in [Monthly Notices of the Royal Astronomical Society] ©: [2019] [owner as specified on the article] Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.-
dc.subjectgamma-ray burst-
dc.subjectgeneral-
dc.subjectgamma-ray burst-
dc.subjectindividual-
dc.subjectradiation mechanism-
dc.titleOn the α-intensity correlation in gamma-ray bursts: subphotospheric heating with varying entropy-
dc.typeArticle-
dc.identifier.emailYu, HF: davidyu@hku.hk-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.1093/mnras/stz083-
dc.identifier.scopuseid_2-s2.0-85063384317-
dc.identifier.hkuros298849-
dc.identifier.volume484-
dc.identifier.issue2-
dc.identifier.spage1912-
dc.identifier.epage1925-
dc.publisher.placeUnited Kingdom-

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