J/A+A/589/A98ivo://CDS.VizieR/J/A+A/589/A98doi:10.26093/cds/vizier.35890098CDSGuidorzi C.Dichiara S.Amati L.2017-09-19T14:21:04Z2016-04-19T08:35:33ZCDS support team

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

cds-question@unistra.frgamma-ray-astronomyspectroscopyTiming analysis can be a powerful tool for shading light on the still obscure emission physics and geometry of the prompt emission of gamma-ray bursts (GRBs). Fourier power density spectra (PDS) characterise time series as stochastic processes and can be used to search for coherent pulsations and, more in general, to investigate the dominant variability timescales in astrophysical sources. Because of the limited duration and of the statistical properties involved, modelling the PDS of individual GRBs is challenging, and only average PDS of large samples have been discussed in the literature thus far. We aim at characterising the individual PDS of GRBs to describe their variability in terms of a stochastic process, to explore their variety, and to carry out for the first time a systematic search for periodic signals and for a link between PDS properties and other GRB observables. We present a Bayesian procedure which uses a Markov chain Monte Carlo technique and apply it to study the individual power density spectra of 215 bright long GRBs detected with the Swift Burst Alert Telescope in the 15-150keV band from January 2005 to May 2015. The PDS are modelled with a power-law either with or without a break. Two classes of GRBs emerge: with or without a unique dominant time scale. A comparison with active galactic nuclei (AGNs) reveals similar distributions of PDS slopes. Unexpectedly, GRBs with subsecond dominant timescales and duration longer than a few ten seconds in the source frame appear to be either very rare or altogether absent. Three GRBs are found with possible evidence for periodic signal at 3.0-3.2{sigma} (Gaussian) significance, corresponding to a multi-trial chance probability of ~1%. Thus, we found no compelling evidence for periodic signal in GRBs. The analogy between the PDS of GRBs and of AGNs could tentatively hint at similar stochastic processes that rule BH accretion across different BH mass scales and objects. In addition, we find evidence that short dominant timescales and duration are not completely independent of each other, in contrast with commonly accepted paradigms.2016A&A...589A..98Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/589/A98CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/777/132 : A search for progenitors of short GRBs (Dichiara+, 2013)J/A+A/589/A97 : GRBs Ep and Fourier PDS slope correlation (Dichiara+, 2016)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/589/A98https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/589/A98http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/589/A98https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/589/A98https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/589/A98http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/589/A98GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/589/A98/table1 (Time intervals for calculating the PDS referred to trigger times, T90, redshifts)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/589/A98/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/589/A98/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/589/A98/table1?GETtext/xml+votable180.050000true358.446833365.93338890.0055555555555555566/205 462 500 1102 1507 2044 2238 2296 2925 2948 3089 3586 3589 3659 3700 4449 4868 5625 5840 5941 6261 6523 6758 7227 7518 7532 7558 7589 8074 8569 8798 9069 9370 9750 9827 9926 9989 10094 10178 10447 10519 10666 10704 11220 11372 11657 11822 12134 13363 13558 13694 14059 14259 14335 14781 14977 15485 15498 15530 15683 15702 15915 15972 16057 16064 16186 16232 16282 16292 16400 16661 17316 17411 17814 18445 18728 18777 18930 18945 19436 19510 19731 19890 20030 20372 20393 20401 20460 20668 21284 21360 21482 21595 21903 21962 23514 24097 24495 25174 25529 25733 26013 26910 27284 27566 27810 27911 27933 27962 28555 28729 28863 28930 29056 29179 29212 29446 29731 29816 29867 30040 30385 30471 30557 30595 30692 31028 31092 31185 31281 31494 31547 32234 32239 32467 32713 32880 33004 33278 33323 33525 33735 33845 33860 34461 34465 34605 34832 35256 35615 35633 35702 35844 36066 36074 36460 36610 37071 37324 37391 38301 39041 39224 39553 39829 40167 40249 40273 40433 40611 41020 41555 41755 42545 42840 42901 43045 43280 44160 44436 44773 44793 44822 44857 45137 45205 45399 45468 45483 45510 45548 45836 45938 46022 46218 46250 46953 47148 47162 47362 47459 47911 48054 48189 48319 48422 48447 48458 49004 49034https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/589/A98?format=asciiGamma-rayOpticaldefaultJ/A+A/589/A98/table4Best fit model and parameters (1 sigma) for hard energy channel (50-150keV)GRBGRB namemeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintModelBest-fit model of the PDSstat.param;meta.modelledcharlogNBest-fit log10(normalisation) of the PDSstat.fit.paramfloate_logNError (1 sigma) on logNstat.errorfloatlogfb? Best-fit log10(break frequency/Hz) (--- when not available)log(Hz)stat.fit.paramfloatnullablee_logfb? Error (1 sigma) on logfblog(Hz)stat.errorfloatnullablealphaBest-fit PDS slope (model parameter alpha)spect.indexfloate_alphaError (1 sigma) on Alphastat.error;pos.eq.rafloatBBest-fit white noise level (model param B)stat.fit.paramfloate_BError (1 sigma) on Bstat.errorfloatpTRP-value of TR statisticstat.fit.goodnessfloatpADP-value of Anderson-Darling statisticstat.fit.goodnessfloatpKSP-value of Kolmogorov-Smirnov statisticstat.fit.goodnessfloatJ/A+A/589/A98/table1Time intervals for calculating the PDS referred to trigger times, T90, redshiftsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGRBGRB namemeta.id;meta.maincharTstartStart since the trigger timestime.startdoubleTstopStop since the trigger timestime.epochdoubleT7sigmaDuration of T(7sigma) intervalstime.durationdoubleT90Duration of T90 intervalstime.durationdoubleCatCatalogue name used for T90 (1)meta.id;instr.setup;meta.tablecharz? GRB Redshift (NA when not available)src.redshiftfloatnullabler_z? Reference for redshift, in refs.dat filemeta.ref;pos.frameintnullableSimbadSimbad column added by the CDSmeta.ref.urlchar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.mainnullable_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainnullableJ/A+A/589/A98/refsReferencesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRefReference codemeta.noteintBibCodeBibCodemeta.bib.bibcodecharAutAuthor's namemeta.bib.authorcharJ/A+A/589/A98/table2Best fit model and parameters (1 sigma) for total energy passband (15-150keV)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGRBGRB namemeta.id;meta.maincharModelBest-fit model of the PDSstat.param;meta.modelledcharlogNBest-fit log10(normalisation) of the PDSstat.fit.paramfloate_logNError (1 sigma) on logNstat.errorfloatlogfb? Best-fit log10(break frequency/Hz) (--- when not available)log(Hz)stat.fit.paramfloatnullablee_logfb? Error (1 sigma) on logfblog(Hz)stat.errorfloatnullablealphaBest-fit PDS slope (model parameter alpha)spect.indexfloate_alphaError (1 sigma) on alphastat.error;pos.eq.rafloatBBest-fit white noise level (model param B)stat.fit.paramfloate_BError (1 sigma) on Bstat.errorfloatpTRP-value of TR statisticstat.fit.goodnessfloatpADP-value of Anderson-Darling statisticstat.fit.goodnessfloatpKSP-value of Kolmogorov-Smirnov statisticstat.fit.goodnessfloatNpNumber of pulses as determined with MEPSAmeta.numberintJ/A+A/589/A98/table3Best fit model and parameters (1 sigma) for soft energy channel (15-50keV)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGRBGRB namemeta.id;meta.maincharModelBest-fit model of the PDSstat.param;meta.modelledcharlogNBest-fit log10(normalisation) of the PDSstat.fit.paramfloate_logNError (1 sigma) on logNstat.errorfloatlogfb? Best-fit log10(break frequency/Hz) (--- when not available)log(Hz)stat.fit.paramfloatnullablee_logfb? Error (1 sigma) on logfblog(Hz)stat.errorfloatnullablealphaBest-fit PDS slope (model parameter alpha)spect.indexfloate_alphaError (1 sigma) on alphastat.error;pos.eq.rafloatBBest-fit white noise level (model param B)stat.fit.paramfloate_BError (1 sigma) on Bstat.errorfloatpTRP-value of TR statisticstat.fit.goodnessfloatpADP-value of Anderson-Darling statisticstat.fit.goodnessfloatpKSP-value of Kolmogorov-Smirnov statisticstat.fit.goodnessfloat