Nonthermal gamma-ray and X-ray flashes from shock breakout in gamma-ray bursts/supernovae

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dc.creatorWang, Xiang-Yu
dc.creatorLi, Zhuo
dc.creatorWaxman, Eli
dc.creatorMeszaros, Peter
dc.date2006-08-02
dc.date2007-04-26
dc.date.accessioned2026-07-07T11:04:07Z
dc.date.available2026-07-07T11:04:07Z
dc.descriptionThermal X-ray emission which is simultaneous with the prompt gamma-rays has been detected for the first time from a supernova connected with a gamma-ray burst (GRB), namely GRB060218/SN2006aj. It has been interpreted as arising from the breakout of a mildly relativistic, radiation-dominated shock from a dense stellar wind surrounding the progenitor star. There is also evidence for the presence of a mildly relativistic ejecta in GRB980425/SN1998bw, based on its X-ray and radio afterglow. Here we study the process of repeated bulk Compton scatterings of shock breakout thermal photons by the mildly relativistic ejecta. During the shock breakout process, a fraction of the thermal photons would be repeatedly scattered between the pre-shock material and the shocked material as well as the mildly relativistic ejecta and, as a result, the thermal photons get boosted to increasingly higher energies. This bulk motion Comptonization mechanism will produce nonthermal gamma-ray and X-ray flashes, which could account for the prompt gamma-ray burst emission in low-luminosity supernova-connected GRBs, such as GRB060218. A Monte Carlo code has been developed to simulate this repeated scattering process, which confirms that a significant fraction of the thermal photons get "accelerated" to form a nonthermal component, with a dominant luminosity. This interpretation for the prompt nonthermal emission of GRB060218 may imply that either the usual internal shock emission from highly relativistic jets in these low-luminosity GRBs is weak, or alternatively, that there are no highly relativistic jets in this peculiar class of bursts.
dc.descriptionAccepted for publication in ApJ; Introduction expanded, references added, conclusions unchanged; total 7 pages including 2 color figures and 1 table
dc.identifierhttps://arxiv.org/abs/astro-ph/0608033
dc.identifierhttp://arxiv.org/abs/astro-ph/0608033
dc.identifierAstrophys.J.664:1026-1032,2007
dc.identifierdoi:10.1086/519228
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/188779
dc.subjectAstrophysics
dc.titleNonthermal gamma-ray and X-ray flashes from shock breakout in gamma-ray bursts/supernovae
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