Open AccessRadiation diffusion in a ultra-relativistic expanding shell in relation to gamma-ray bursts
Author(s) -
І. А. Сіўцоў,
А. Э. Кургузава
Publication year - 2021
Publication title -
vescì nacyânalʹnaj akadèmìì navuk belarusì. seryâ fìzìka-matèmatyčnyh navuk
Language(s) - English
Resource type - Journals
eISSN - 2524-2415
pISSN - 1561-2430
DOI - 10.29235/1561-2430-2021-57-1-85-98
Subject(s) - physics , diffusion , radiation , photon , heavy traffic approximation , photon diffusion , computational physics , gamma ray , radiant energy , astrophysics , nuclear physics , optics , quantum mechanics , statistics , mathematics , light source
The present-day observational data obtained by satellite observatories cover seven decades of gamma-ray energy, and there is no universal general model describing the formation of the spectrum. Therefore, it is important to describe the initial stages of radiation propagation in an ultrarelativistically expanding shell. The aim of this study was to obtain equations describing the propagation of radiation in a relativistically expanding shell in the diffusion limit, solve them for natural initial data, and apply the results obtained to the initial radiation of gamma-ray bursts. The following results were obtained: the initial stage of the gamma-ray burst in a photon-thin case can be described by radiation diffusion in an ultrarelativistically expanding shell; the time interval at which it is still possible to use the diffusion approximation increases with increasing the depth inside the shell quadratically; the value of the depth beyond which the diffusion approximation can be used increases, and the value of the radiation intensity decreases in diffusion time approaches; during the main radiation of the photon-thin shell, the diffusion approximation is suitable for most of the jet. The parameters of emission are close to the ones of short gamma-ray bursts.