J/ApJ/787/66ivo://CDS.VizieR/J/ApJ/787/66doi:10.26093/cds/vizier.17870066CDSZhang B.-B.Zhang B.Murase K.Connaughton V.Briggs M.S.2017-07-21T10:53:05Z2017-07-04T12:01:45ZCDS support team

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

cds-question@unistra.frgamma-ray-astronomySeveral gamma-ray bursts (GRBs) last much longer (~hours) in {gamma}-rays than typical long GRBs (~minutes), and it has recently been proposed that these "ultra-long GRBs" may form a distinct population, probably with a different (e.g., blue supergiant) progenitor than typical GRBs. However, Swift observations suggest that many GRBs have extended central engine activities manifested as flares and internal plateaus in X-rays. We perform a comprehensive study on a large sample of Swift GRBs with X-Ray Telescope observations to investigate GRB central engine activity duration and to determine whether ultra-long GRBs are unusual events. We define burst duration t_burst_ based on both {gamma}-ray and X-ray light curves rather than using {gamma}-ray observations alone. We find that t_burst_can be reliably measured in 343 GRBs. Within this "good" sample, 21.9% GRBs have t_burst_>~10^3^ s and 11.5% GRBs have t_burst_>~10^4^ s. There is an apparent bimodal distribution of t_burst_ in this sample. However, when we consider an "undetermined" sample (304 GRBs) with t_burst_ possibly falling in the gap between GRB duration T_90_ and the first X-ray observational time, as well as a selection effect against t_burst_ falling into the first Swift orbital "dead zone" due to observation constraints, the intrinsic underlying t_burst_ distribution is consistent with being a single component distribution. We found that the existing evidence for a separate ultra-long GRB population is inconclusive, and further multi-wavelength observations are needed to draw a firmer conclusion. We also discuss the theoretical implications of our results. In particular, the central engine activity duration of GRBs is generally much longer than the {gamma}-ray T_90_ duration and it does not even correlate with T_90_. It would be premature to make a direct connection between T_90_ and the size of the progenitor star.2014ApJ...787...66Zhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/787/66CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/448/L9 : Position catalogue of Swift XRT afterglows (Moretti+, 2006)J/ApJ/701/824 : Afterglows of short and long-duration GRBsJ/MNRAS/397/1177 : Swift-XRT observations of GRBs (Evans+, 2009)J/ApJ/711/495 : Durations of Swift/BAT GRBs (Butler+, 2010)J/ApJ/800/16 : Swift-XRT long GRB durations (Boer+, 2015)J/ApJS/224/20 : 10yr of Swift/XRT obs. of GRBs (Yi+, 2016)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/787/66https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/787/66http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/787/66https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/787/66https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/787/66http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/787/66GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/787/66/table1 (t_burst_ of the Each GRB in Our Good Sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/787/66/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/787/66/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/787/66/table1?GETtext/xml+votable180.050000true188.5212527.95072220.0055555555555555566/186 314 393 453 462 500 550 699 877 908 923 1507 1882 2238 2296 2315 2357 2456 2473 2735 2793 2948 2949 3038 3111 3388 3506 3536 3586 3589 3611 3700 3935 4312 4323 4341 4371 4449 4450 4485 4788 4977 5080 5162 5253 5525 5606 5625 5726 5791 6004 6111 6862 6961 7043 7084 7156 7300 7518 7532 7685 8021 8182 8569 8761 8798 8932 8954 9024 9069 9321 9395 9682 9714 9750 9827 9989 10135 10407 10445 10602 10680 10704 10723 10852 10912 10914 11248 11372 11649 11657 11673 11822 11905 12020 12134 12155 12226 13475 13558 13574 13694 13787 13889 13898 14248 14555 14846 14852 14892 14977 15197 15214 15415 15485 15530 15595 15613 15615 15702 15820 15915 15972 15995 16057 16064 16072 16078 16172 16232 16282 16292 16400 16489 16546 16661 16769 17279 17316 17411 17561 17721 17733 17980 18097 18167 18221 18258 18494 18681 18728 18777 18910 18930 19049 19168 19331 19544 19731 20191 20263 20372 20655 20668 20710 20753 20883 21284 21360 21595 21766 21903 21962 22157 22559 22580 22624 22916 23138 23585 24036 24041 25120 25131 25174 25312 25394 25469 25529 25901 25926 25946 26013 26441 26452 26503 26671 26831 26910 27085 27289 27566 27933 27962 28033 28202 28224 28467 28496 28555 28863 28867 29446 29816 30040 30235 30692 31028 31092 31143 31281 31385 31521 31547 31583 31700 31847 31982 32110 32310 32467 32676 32713 32790 33034 33146 33195 33265 33278 33475 33482 33617 33841 34147 34364 34435 34461 34465 34699 34949 35045 35088 35330 35393 35566 35633 35844 36066 36292 36374 36460 36528 37007 37255 37324 37383 37459 37737 38046 38068 38413 38465 38504 38926 39008 39076 39224 39374 39432 39987 39993 40167 40272 40273 40389 40433 40559 40642 40778 41020 41135 41555 42319 42473 42611 42901 42952 43193 43201 43920 43947 44125 44419 44436 44720 44822 44857 44861 45008 45088 45399 45401 45402 45422 45483 45561 45729 45777 45828 45836 45938 46022 46218 46250 46395 46510 46953 46989 47162 47459 47911 47945 47991 48054 48189 48319 48371 48422 48458 49004 49034https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/787/66?format=asciiGamma-raydefaultJ/ApJ/787/66/table1t_burst_ of the Each GRB in Our Good SampleGRBGRB identifier (YYMMDDA)meta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintl_logtburst[>=~ ] Limit flag on logtburstmeta.code.errorcharlogtburstLog t_burst_log(s)time.intervalfloate_logtburst? Uncertainty in logtburstlog(s)stat.errorfloatnullablen_logtburst[T90 ] Note on logtburst (1)meta.notecharSimbadSimbad 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