J/MNRAS/485/474ivo://CDS.VizieR/J/MNRAS/485/474doi:10.26093/cds/vizier.74850474CDSAhlgren B.Larsson J.Ahlberg E.Lundman C.Ryde F.Pe'er A.2024-08-19T20:17:46Z2022-10-18T13:49:26ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frgamma-ray-astronomygamma-ray-burstsastronomical-modelsIt has been suggested that the prompt emission in gamma-ray bursts (GRBs) could be described by radiation from the photosphere in a hot fireball. Such models must be tested by directly fitting them to data. In this work we use data from the Fermi Gamma-ray Space Telescope and consider a specific photospheric model, in which the kinetic energy of a low-magnetization outflow is dissipated locally by internal shocks below the photosphere. We construct a table model with a physically motivated parameter space and fit it to time-resolved spectra of the 36 brightest Fermi GRBs with a known redshift. We find that about two-thirds of the examined spectra cannot be described by the model, as it typically underpredicts the observed flux. However, since the sample is strongly biased towards bright GRBs, we argue that this fraction will be significantly lowered when considering the full population. From the successful fits we find that the model can reproduce the full range of spectral slopes present in the sample. For these cases we also find that the dissipation consistently occurs at a radius of ~10^12^cm and that only a few per cent efficiency is required. Furthermore, we find a positive correlation between the fireball luminosity and the Lorentz factor. Such a correlation has been previously reported by independent methods. We conclude that if GRB spectra are due to photospheric emission, the dissipation cannot only be the specific scenario we consider here.2019MNRAS.485..474Ahttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/485/474CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJS/223/28 : The third Fermi/GBM GRB catalog (6yr) (Bhat+, 2016)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/485/474https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/485/474http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/485/474https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/485/474https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/485/474http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/485/474GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/485/474/table2 (Best-fitting parameter values for accepted fits with DREAM1.2)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/485/474/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/485/474/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/485/474/table2?GETtext/xml+votable180.050000true189.530833316.82941670.0055555555555555566/228 3586 4449 9431 11220 13779 15340 16187 16282 17411 19097 21284 21595 26365 27962 29731 32646 33146 36066 36460 37391 37505 45401 45835 46212https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/485/474?format=asciiGamma-raydefaultJ/MNRAS/485/474/table2Best-fitting parameter values for accepted fits with DREAM1.2GammaBulk Lorentz factorstat.fit.paramfloatb_L052Minimal value of L052 (1)stat.value;stat.minfloatSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBurstBurst identifier (Fermi bnYYMMDDddd in Simbad)meta.id;meta.mainchartstartStart time of time binstime.startfloattstopStop time of time binstime.endfloatedFraction of the kinetic energy of the protonsphys.energy;arith.ratiofloatb_ed? Minimal value of ed (1)stat.value;stat.minfloatnullableB_ed? Maxmal value of ed (1)stat.valuefloatnullableL052Fireball luminosity (2)phys.luminosityfloatB_L052? Maximal value of L052stat.valuefloatnullableb_Gamma? Minimal value of Gamma (1)stat.value;stat.minfloatnullableB_Gamma? Maximal value of Gamma (1)stat.valuefloatnullablerdDissipation radius (3)1e+12cmphys.size.radiusfloate_rdError on rd1e+12cmstat.errordouble_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.main