J/A+A/609/A112ivo://CDS.VizieR/J/A+A/609/A112doi:10.26093/cds/vizier.36090112CDSGhirlanda G.Nappo F.Ghisellini G.Melandri A.Marcarini G.Nava L.,Salafia O.S.Campana S.Salvaterra R.2018-09-25T12:08:02Z2018-06-12T12:05:41ZCDS support team

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

cds-question@unistra.frgamma-ray-astronomygamma-ray-burstsKnowledge of the bulk Lorentz factor {Gamma}_0_ of gamma-ray bursts (GRBs) allows us to compute their comoving frame properties shedding light on their physics. Upon collisions with the circumburst matter, the fireball of a GRB starts to decelerate, producing a peak or a break (depending on the circumburst density profile) in the light curve of the afterglow. Considering all bursts with known redshift and with an early coverage of their emission, we find 67 GRBs (including one short event) with a peak in their optical or GeV light curves at a time t_p_. For another 106 GRBs we set an upper limit t_p_^UL^. The measure of t_p_ provides the bulk Lorentz factor {Gamma}_0_ of the fireball before deceleration. We show that t_p_ is due to the dynamics of the fireball deceleration and not to the passage of a characteristic frequency of the synchrotron spectrum across the optical band. Considering the t_p_ of 66 long GRBs and the 85 most constraining upper limits, we estimate {Gamma}_0_ or a lower limit {Gamma}_0_^LL^. Using censored data analysis methods, we reconstruct the most likely distribution of t_p_. All t_p_ are larger than the time T_p,{gamma}_ when the prompt {gamma}-ray emission peaks, and are much larger than the time T_ph_ when the fireball becomes transparent, that is, t_p_>T_p,{gamma}_>T_ph_. The reconstructed distribution of {Gamma}_0_ has median value ~300 (150) for a uniform (wind) circumburst density profile. In the comoving frame, long GRBs have typical isotropic energy, luminosity, and peak energy <E_iso_>=3(8)x10^50^erg, <L_iso_>=3(15)x10^47^erg/s, and <E_peak_>=1(2)keV in the homogeneous (wind) case. We confirm that the significant correlations between {Gamma}_0_ and the rest frame isotropic energy (E_iso_), luminosity (L_iso_), and peak energy (E_p_) are not due to selection effects. When combined, they lead to the observed E_p_-E_iso_ and E_p_-L_iso_ correlations. Finally, assuming a typical opening angle of 5 degrees, we derive the distribution of the jet baryon loading which is centered around a few 10^-6^M_{\sun}_.2018A&A...609A.112Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/609/A112CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/609/A112https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/609/A112http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/609/A112https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/609/A112https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/609/A112http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/609/A112GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/609/A112/tablea1 (*GRBs with measured tp (69 events) from the peak of the light curve)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/609/A112/tablea1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/609/A112/tablea1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/609/A112/tablea1?GETtext/xml+votable180.050000true179.1165.20027780.0055555555555555566/228 500 557 646 699 908 962 2044 2336 3089 3111 3536 3586 3839 4341 4449-4450 5051 5073 5376 5625 5840 6141 6258 6261 6521 6523 7227 7518 7532 7589 7750 8074 8425 9022 9321 9431 9643 9662 9897 9910 9989 10080 10094 10407 10424 10447 10519 10589 10704 10912 11008 11058 11220 11308 11657 11695 11822 12230 13312 13694 13924 15233 15530 15915 16057 16187 16282 17316 17411 17453 17749 17814 17982 18030 18728 18777 18978 19097 19164 19519 19731 19865 20372 20401 20460 21284 21595 22008 22129 22619 24072 25148 25452 25901 25946 26365 26503 27284 27541 27933 27961-27962 28063 28344 28555 28930 29731 30557 31185 31281 31385 31494 32239 32310 32646 32713 33278 33525 33735 33813 33832 33860 34440 34465 34590 34788 34832 34949 35330 35633 36074 36460 37391 37459 37505 37628 39076 39594 39993 40249 40433 40560 40778 40784 41095 42545 43853 44436 44857 45008 45347 45401 46022 46212 46218 46250 46510 46594 46899 46989 47031 47148 47162 47245 47620 48007 48447 48458 48804 49004https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/609/A112?format=asciiGamma-raydefaultJ/A+A/609/A112/tablea1*GRBs with measured tp (69 events) from the peak of the light curvezRedshiftsrc.redshiftfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGRBGRB designation (NNNNNNA)meta.id;meta.maincharn_GRB[gsb *] Note on GRB (1)meta.notecharf_GRB[SL ] L for LAT light curve, SL for for the short GRB 090510meta.codecharlogEpPeak energylog(keV)phys.energy;stat.maxfloate_logEprms uncertainty on logEplog(keV)stat.errorfloatlogEisoIsotropic energylog(1e-07J)em.energyfloate_logEisorms uncertainty on logEisolog(1e-07J)stat.errorfloatlogLisoIsotropic luminositylog(1e-07W)phys.luminosityfloate_logLisorms uncertainty on logLisolog(1e-07W)stat.errorfloatl_logtp[<= ] Limit flag on logtpmeta.code.errorcharlogtpAfterglow peak timelog(s)time.epoch;stat.maxfloatRefReference, in refs.dat filemeta.ref;pos.frame;meta.filecharSimbadSimbad 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.mainJ/A+A/609/A112/refsReferencesBibCodeBibCodemeta.bib.bibcodecharComCommentsmeta.notecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRefReference codemeta.note;meta.maincharprimary