1997/04/30 by Daniel E. Reichart · 2 citations
Engineering · Physics and Astronomy · #Astronomy and Astrophysical Research #CCD and CMOS Imaging Sensors #Gamma-ray bursts and supernovae #astro-ph
paper · pdf · doi:10.1086/310819
Accepted to the Astrophysical Journal Letters, 11 pages, LaTeX
arxiv created 1997/06/08 · openalex publication_date 1997/08/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
GRB 970228 is the first gamma-ray burst (GRB) for which prolonged postburst transient X-ray, optical, and infrared emission has been detected. Recent Hubble Space Telescope ( HST ) observations show that the transient consists of two components: a point source, which is known to be fading, and an extended source, which is possibly fading. I fit standard fireball remnant models to the first month of X-ray, optical, and infrared measurements, which may be done without assuming a GRB distance scale. I show that its emission is consistent with that of the remnant of a relativistically expanding impulsive fireball in which a forward shock dominates the emission of the GRB event: the piston model. However, two discrepant measurements may indicate that the postburst flux varies by a factor of ~3 on timescales of days or weeks. Furthermore, using the HST observations and the fitted model, I show that the extended object probably is fading, which may place GRB 970228 at Galactic halo distances.