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dc.contributor.authorFRONTERA, F
dc.contributor.authorFeroci, Marco
dc.contributor.authorGandolfi, Giangiacomo
dc.contributor.authorIN'T ZAND, J
dc.contributor.authorNICASTRO, L
dc.contributor.authorANTONELLI, LA
dc.contributor.authorDe Pasquale, Massımılıano
dc.contributor.authorSTRATTA, G
dc.contributor.authorFIORE, F
dc.contributor.authorPiro, Luigi
dc.contributor.authorPerna, Rosalba
dc.contributor.authorCosta, Enrico
dc.date.accessioned2021-03-03T13:17:18Z
dc.date.available2021-03-03T13:17:18Z
dc.date.issued2003
dc.identifier.citationDe Pasquale M., Piro L., Perna R., Costa E., Feroci M., Gandolfi G., IN'T ZAND J., NICASTRO L., FRONTERA F., ANTONELLI L., et al., "A comparative study of the X-ray afterglow properties of optically bright and dark gamma-ray bursts", ASTROPHYSICAL JOURNAL, cilt.592, sa.2, ss.1018-1024, 2003
dc.identifier.issn0004-637X
dc.identifier.othervv_1032021
dc.identifier.otherav_3320def2-6cdf-4ec0-ba50-286f21a975e6
dc.identifier.urihttp://hdl.handle.net/20.500.12627/38648
dc.identifier.urihttps://doi.org/10.1086/375854
dc.description.abstractWe have examined the complete set of X-ray afterglow observations of dark and optically bright gamma-ray bursts (GRBs) performed by BeppoSAX through 2001 February. X-ray afterglows are detected in similar to90% of the cases. We do not find significant differences in the X-ray spectral shape, in particular no increased X-ray absorption in GRBs without optical transient (dark GRBs) compared to GRBs with optical transient (OTGRBs). Rather, we find that the 1.6-10 keV flux of OTGRBs is on average about 5 times larger than that of the dark GRBs. A Kolmogorov-Smirnov test shows that this difference is significant at 99.8% probability. Under the assumption that dark and OTGRBs have similar spectra, this could suggest that the first are uncaught in the optical band because they are just faint sources. In order to test this hypothesis, we have determined the optical-to-X-ray flux ratios of the sample. OTGRBs show a remarkably narrow distribution of flux ratios, which corresponds to an average optical-to-X-ray spectral index (α) over bar (OT)(ox) = 0.794 +/- 0.054. We find that, while 75% of dark GRBs have flux ratio upper limits still consistent with those of OT GRBs, the remaining 25% are 4-10 times weaker in optical than in X-rays. The significance of this result is greater than or equal to2.6 sigma. If this subpopulation of dark GRBs were constituted by objects assimilable to OTGRBs, they should have shown optical fluxes higher than upper limits actually found. We discuss the possible causes of their behavior, including a possible occurrence in high-density clouds or origin at very high redshift and a connection with ancient, Population III stars.
dc.language.isoeng
dc.subjectAstronomi ve Astrofizik
dc.subjectTemel Bilimler
dc.subjectFizik
dc.subjectTemel Bilimler (SCI)
dc.subjectUzay bilimi
dc.subjectASTRONOMİ VE ASTROFİZİK
dc.titleA comparative study of the X-ray afterglow properties of optically bright and dark gamma-ray bursts
dc.typeMakale
dc.relation.journalASTROPHYSICAL JOURNAL
dc.contributor.department, ,
dc.identifier.volume592
dc.identifier.issue2
dc.identifier.startpage1018
dc.identifier.endpage1024
dc.contributor.firstauthorID103334


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