Optical light curve and cooling break of GRB 050502A

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dc.authoridAlatalo, Katherine/0000-0002-4261-2326
dc.authoridGuver, Tolga/0000-0002-3531-9842
dc.authoridAshley, Michael/0000-0003-1412-2028
dc.authoridFlewelling, Heather/0000-0002-1050-4056
dc.authoridRujopakarn, Wiphu/0000-0002-0303-499X
dc.authoridMirabal, Nestor/0000-0002-7021-5838
dc.authoridGogus, Ersin/0000-0002-5274-6790
dc.contributor.authorYost, SA
dc.contributor.authorAlatalo, K
dc.contributor.authorRykoff, ES
dc.contributor.authorAharonian, F
dc.contributor.authorAkerlof, CW
dc.contributor.authorAshley, MCB
dc.contributor.authorBlake, CH
dc.date.accessioned2025-01-27T20:31:43Z
dc.date.available2025-01-27T20:31:43Z
dc.date.issued2006
dc.departmentÇanakkale Onsekiz Mart Üniversitesi
dc.description.abstractWe present light curves of the afterglow of GRB 050502A, including very early data at t - t(GRB) < 60 s. The light curve is composed of unfiltered ROTSE-IIIb optical observations from 44 s to 6 hr postburst, R-band MDM observations from 1.6 to 8.4 hr postburst, and PAIRITEL JHKs observations from 0.6 to 2.6 hr postburst. The optical light curve is fit by a broken power law, where t(alpha) steepens from alpha = 1.13 +/- 0.02 to -1.44 +/- 0.02 at similar to 5700s. This steepening is consistent with the evolution expected for the passage of the cooling frequency v(c) through the optical band. Even in our earliest observation at 44 s postburst, there is no evidence that the optical flux is brighter than a backward extrapolation of the later power law would suggest. The observed decay indices and spectral index are consistent with either an ISM or a wind fireball model, but slightly favor the ISM interpretation. The expected spectral index in the ISM interpretation is consistent within 1 sigma with the observed spectral index beta = -0.8 +/- 0.1; the wind interpretation would imply a spectral index slightly (similar to 2 sigma) shallower than observed. A small amount of dust extinction at the source redshift could steepen an intrinsic spectrum sufficiently to account for the observed value of beta. In this picture, the early optical decay, with the peak at or below 4.7 x 10(14) Hz at 44 s, requires very small electron and magnetic energy partitions from the fireball.
dc.identifier.doi10.1086/498134
dc.identifier.endpage966
dc.identifier.issn0004-637X
dc.identifier.issn1538-4357
dc.identifier.issue2
dc.identifier.scopus2-s2.0-32044455838
dc.identifier.scopusqualityQ1
dc.identifier.startpage959
dc.identifier.urihttps://doi.org/10.1086/498134
dc.identifier.urihttps://hdl.handle.net/20.500.12428/23248
dc.identifier.volume636
dc.identifier.wosWOS:000234469400033
dc.identifier.wosqualityQ1
dc.indekslendigikaynakWeb of Science
dc.indekslendigikaynakScopus
dc.language.isoen
dc.publisherIop Publishing Ltd
dc.relation.ispartofAstrophysical Journal
dc.relation.publicationcategoryinfo:eu-repo/semantics/openAccess
dc.rightsinfo:eu-repo/semantics/openAccess
dc.snmzKA_WoS_20250125
dc.subjectgamma rays : bursts
dc.titleOptical light curve and cooling break of GRB 050502A
dc.typeArticle

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