1997/09/28 by A. Panaitescu, P. Mészáros, P. Meszaros · 4 citations
Physics and Astronomy · #Afterglow #Astrophysics and Cosmic Phenomena #Bolometer #Brightness #Ellipsoid #Gamma-ray bursts and supernovae #Pulsars and Gravitational Waves Research #Radiation #Radiative transfer #Surface (topology) #Surface brightness #astro-ph
paper · pdf · doi:10.1086/311127
published as Astrophys.J. 493 (1998) L31 · Ap.J.(Letters), subm. 9/28/97, latex (aaspp4), 11 pages including two postscript figures
arxiv created 1997/09/28 · openalex publication_date 1998/01/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We derive the equation for the surface of equal arrival time of radiation from a thin relativistic shell interacting with an external medium, representing the afterglow of a gamma-ray burst produced by a fireball. Due to the deceleration, these surfaces become distorted ellipsoids and, at late times, most of the light comes from a ringlike region whose width depends only on age. We analyze the shape of these surfaces for different dynamic and radiative regimes and homogeneous or power-law external densities. We tabulate the most relevant parameters describing the surfaces and the source brightness distribution, both for bolometric and fixed frequency observations, which are useful for more accurate analytic estimates of the afterglow evolution.