1999/10/15 by J. Greiner, D. H. Hartmann, Greiner, J. +9
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics (astro-ph) #FOS: Physical sciences #Gamma-ray bursts and supernovae #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9910300
12 pages with aa.sty and 6 Figs; (to appear in AA); also available from http://www.aip.de/~jcg/publis.html
arxiv created 1999/10/15 · openalex publication_date 1999/10/15 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We describe a search for X-ray afterglows from gamma-ray bursts using the ROSAT all-sky survey (RASS) data. If the emission in the soft X-ray band is significantly less beamed than in the gamma-ray band, we expect to detect many afterglows in the RASS. We found 23 afterglow candidates, where about 4 detections are predicted. However, follow-up spectroscopy of several counterpart candidates strongly suggests a flare star origin of the RASS events in many cases. We conclude that the RASS data are consistent with comparable beaming angles in the X-ray (within a few hours of the burst) and gamma-ray bands. However, models predicting a large amount of energy emerging as a nearly isotropic X-ray component of the early afterglow are severely constrained by the ROSAT data. In particular, a so far undetected class of ``dirty fireballs'' and delayed ``rebursts'' are constrained.