File Download
  Links for fulltext
     (May Require Subscription)
Supplementary

Article: Non-Dissipative Photospheres in GRBs: Spectral Appearance in the Fermi/GBM Catalogue

TitleNon-Dissipative Photospheres in GRBs: Spectral Appearance in the Fermi/GBM Catalogue
Authors
Keywordsradiation mechanisms
thermal
methods: data analysis
methods: numerical
gamma-ray burst: general
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. 487 n. 4, p. 5508-5519 How to Cite?
AbstractA large fraction of gamma-ray burst (GRB) spectra are very hard below the peak. Indeed, the observed distribution of sub-peak power-law indices, α, has been used as an argument for a photospheric origin of GRB spectra. Here, we investigate what fraction of GRBs have spectra that are consistent with emission from a photopshere in a non-dissipative outflow. This is the simplest possible photospheric emission scenario. We create synthetic spectra, with a range of peak energies, by folding the theoretical predictions through the detector response of the FERMI/GBM detector. These simulated spectral data are fitted with typically employed empirical models. We find that the low-energy photon indices obtain values ranging −0.4 < α < 0.0, peaking at around −0.1, thus covering a non-negligible fraction of observed values. These values are significantly softer than the asymptotic value of the theoretical spectrum of α ∼ 0.4. The reason for the α values to be much softer than expected, is the limitation of the empirical functions to capture the true curvature of the theoretical spectrum. We conclude that more than a quarter of the bursts in the GBM catalogue have at least one time-resolved spectrum, whose α values are consistent with spectra from a non-dissipative outflow, releasing its thermal energy at the photosphere. The fraction of spectra consistent with emission from the photosphere will increase even more if dissipation of kinetic energy in the flow occurs below the photosphere.
Persistent Identifierhttp://hdl.handle.net/10722/285024
ISSN
2019 Impact Factor: 5.356
2015 SCImago Journal Rankings: 2.806

 

DC FieldValueLanguage
dc.contributor.authorAcuner, Z-
dc.contributor.authorRyde, F-
dc.contributor.authorYu, HF-
dc.date.accessioned2020-08-07T09:05:44Z-
dc.date.available2020-08-07T09:05:44Z-
dc.date.issued2019-
dc.identifier.citationMonthly Notices of the Royal Astronomical Society, 2019, v. 487 n. 4, p. 5508-5519-
dc.identifier.issn0035-8711-
dc.identifier.urihttp://hdl.handle.net/10722/285024-
dc.description.abstractA large fraction of gamma-ray burst (GRB) spectra are very hard below the peak. Indeed, the observed distribution of sub-peak power-law indices, α, has been used as an argument for a photospheric origin of GRB spectra. Here, we investigate what fraction of GRBs have spectra that are consistent with emission from a photopshere in a non-dissipative outflow. This is the simplest possible photospheric emission scenario. We create synthetic spectra, with a range of peak energies, by folding the theoretical predictions through the detector response of the FERMI/GBM detector. These simulated spectral data are fitted with typically employed empirical models. We find that the low-energy photon indices obtain values ranging −0.4 < α < 0.0, peaking at around −0.1, thus covering a non-negligible fraction of observed values. These values are significantly softer than the asymptotic value of the theoretical spectrum of α ∼ 0.4. The reason for the α values to be much softer than expected, is the limitation of the empirical functions to capture the true curvature of the theoretical spectrum. We conclude that more than a quarter of the bursts in the GBM catalogue have at least one time-resolved spectrum, whose α values are consistent with spectra from a non-dissipative outflow, releasing its thermal energy at the photosphere. The fraction of spectra consistent with emission from the photosphere will increase even more if dissipation of kinetic energy in the flow occurs below the photosphere.-
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.rightsThis work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.-
dc.subjectradiation mechanisms-
dc.subjectthermal-
dc.subjectmethods: data analysis-
dc.subjectmethods: numerical-
dc.subjectgamma-ray burst: general-
dc.titleNon-Dissipative Photospheres in GRBs: Spectral Appearance in the Fermi/GBM Catalogue-
dc.typeArticle-
dc.identifier.emailYu, HF: davidyu@hku.hk-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.1093/mnras/stz1356-
dc.identifier.scopuseid_2-s2.0-85070069004-
dc.identifier.hkuros312633-
dc.identifier.volume487-
dc.identifier.issue4-
dc.identifier.spage5508-
dc.identifier.epage5519-
dc.publisher.placeUnited Kingdom-

Export via OAI-PMH Interface in XML Formats


OR


Export to Other Non-XML Formats