J/ApJ/880/76ivo://CDS.VizieR/J/ApJ/880/76doi:10.26093/cds/vizier.18800076CDSAhlgren B.Larsson J.Valan V.Mortlock D.Ryde F.Pe'er A.2021-07-05T06:56:56Z2021-02-01T06:29:06ZCDS support team

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

cds-question@unistra.frgamma-ray-astronomygamma-ray-burstsastronomical-modelsx-ray-sourcesThe jet photosphere has been proposed as the origin for the gamma-ray burst (GRB) prompt emission. In many such models, characteristic features in the spectra appear below the energy range of the Fermi Gamma-ray Burst Monitor (GBM) detectors, so joint fits with X-ray data are important in order to assess the photospheric scenario. Here we consider a particular photospheric model which assumes localized subphotospheric dissipation by internal shocks in a non-magnetized outflow. We investigate it using Bayesian inference and a sample of eight GRBs with known redshifts which are observed simultaneously with Fermi GBM and the Swift X-ray Telescope (XRT). This provides us with an energy range of 0.3keV-40MeV and much tighter parameter constraints. We analyze 32 spectra and find that 16 are well described by the model. We also find that the estimates of the bulk Lorentz factor, {Gamma}, and the fireball luminosity, L_0,52_, decrease while the fraction of dissipated energy, {epsilon}_d_, increases in the joint fits compared to GBM-only fits. These changes are caused by a small excess of counts in the XRT data, relative to the model predictions from fits to GBM-only data. The fact that our limited implementation of the physical scenario yields 50% accepted spectra is promising, and we discuss possible model revisions in the light of the new data. Specifically, we argue that the inclusion of significant magnetization, as well as removing the assumption of internal shocks, will provide better fits at low energies.2019ApJ...880...76Ahttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/880/76CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/609/935 : Gamma-ray burst formation rate (Yonetoku+, 2004)J/A+A/564/A125 : AGN Torus model comparison of AGN in CDFS (Buchner+, 2014)J/MNRAS/454/L31 : GRB prompt emission fitted with DREAM model (Ahlgren+, 2015)J/A+A/609/A112 : Bulk Lorentz factors of gamma-ray bursts (Ghirlanda+, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/880/76https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/880/76http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/880/76https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/880/76https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/880/76http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/880/76GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/880/76/table3 (Point estimates of model parameters and r_d_ for all 21 fits which passed the posterior predictive checks (PPC) for 6 GRBs in our sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/880/76/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/880/76/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/880/76/table3?GETtext/xml+votable180.050000true88.7582917-15.25558330.0055555555555555566/3586 15340 17411 21284 29731 48219https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/880/76?format=asciiGamma-rayX-raydefaultJ/ApJ/880/76/table3Point estimates of model parameters and r_d_ for all 21 fits which passed the posterior predictive checks (PPC) for 6 GRBs in our samplerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGRBGRB namemeta.id;meta.maincharTstart[72.5/147] Time bin, startstime.startfloatTstop[90.2/156] Time bin, stopstime.epochfloated[0.02/0.4] Mean dissipated energy {epsilon}_d_phys.energyfloate_ed[0.02/0.4] 1{sigma} lower uncertainty in edstat.errorfloatE_ed[0.03/0.4] 1{sigma} upper uncertainty in edstat.error;stat.maxfloatL[1.2/89.3] Mean fireball luminosity, L_0,52_1e+45Wphys.luminosityfloate_L[1.1/79.3] 1{sigma} lower uncertainty in L1e+45Wstat.errorfloatE_L[1.3/99.5] 1{sigma} upper uncertainty in L1e+45Wstat.error;stat.maxfloatGamma[77.5/162] Mean coasting bulk Lorentz factorstat.fit.paramfloate_Gamma[71.3/149] 1{sigma} lower uncertainty in Gammastat.errorfloatE_Gamma[82.5/175] 1{sigma} upper uncertainty in Gammastat.error;stat.maxfloatrd[0.9/31.5] Mean dissipation radius1e+12cmphys.size.radiusfloate_rd[0.9/27] 1{sigma} lower uncertainty in rd1e+12cmstat.errorfloatE_rd[1/36.2] 1{sigma} upper uncertainty in rd1e+12cmstat.error;stat.maxfloatNr[0.9/1.4] Mean free relative normalization parameter, cross calibration constantstat.paramfloate_Nr[0.8/1.25] 1{sigma} lower uncertainty in Nrstat.errorfloatE_Nr[1/1.4] 1{sigma} upper uncertainty in Nrstat.error;stat.maxfloatFigFigure part number; column added by CDS from authormeta.idintSimbadSimbad column added by the CDSmeta.ref.urlcharNEDNED column added by the CDSmeta.ref.urlchar_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