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J. Kóbori

Publications and source records attributed to J. Kóbori.

2 recordsLinked to original sources
arXiv2013

Statistical analysis of the prompt and afterglow emission of the three groups of gamma-ray bursts

We investigated the main prompt and afterglow emission parameters of gamma-ray bursts detected by the Burst Alert Telescope (BAT) and X-Ray Telescope installed on the Swift satellite. Our aim was to look for differences or connections between the different types of gamma-ray bursts, so we compared the BAT fluences, 1-sec peak photon fluxes, photon indices, XRT early fluxes, initial temporal decay and spectral indices. We found that there might be a connection between the XRT initial decay index and XRT early flux/BAT photon index. Using statistical tools we also determined that beside the duration and hardness ratios, the means of the γ- and X-ray--fluences and the γ-ray photon index differ significantly between the three types of bursts.

astro-ph.HE↗
arXiv2013

Dependence of the optical brightness on the gamma and X-ray properties of GRBs

The Swift satellite made a real break through with measuring simultaneously the gamma X-ray and optical data of GRBs, effectively. Although, the satellite measures the gamma, X-ray and optical properties almost in the same time a significant fractions of GRBs remain undetected in the optical domain. In a large number of cases only an upper bound is obtained. Survival analysis is a tool for studying samples where a part of the cases has only an upper (lower) limit. The obtained survival function may depend on some other variables. The Cox regression is a way to study these dependencies. We studied the dependence of the optical brightness (obtained by the UVOT) on the gamma and X-ray properties, measured by the BAT and XRT on board of the Swift satellite. We showed that the gamma peak flux has the greatest impact on the afterglow's optical brightness while the gamma photon index and the X-ray flux do not. This effect probably originates in the energetics of the jet launched from the central engine of the GRB which triggers the afterglow.

astro-ph.HE↗