A simple, stringent test on the nature of GRBs' progenitors

Abstract

I show here that the time-delay between the gamma ray burst proper and the onset of the afterglow is a sensitive function of the surrounding density, going from ~10s for typical disk densities to several hours for IGM densities. Since bulk Lorenz factor, explosion energy and environment density can be simultaneously determined from observations of the time-delay and of the afterglow, afterglow observations alone may establish which fraction, if any, of all bursts resides inside galaxies, in their outer haloes, or outright in the IGM medium, subjecting the NS/NS merger hypothesis to a definitive test. If bursts are due to collapse of massive stars, no matter how short the burst, the onset of the afterglow should be immediate.

Accepted for publication in Astroparticle Physics. Standard LateX + 1 EPS figure

References in corpus (4)

• A 450-day light curve of the radio afterglow of GRB 970508: Fireball calorimetry
• The discovery of polarization in the afterglow of GRB 990510 with the ESO Very Large Telescope
• SupraNova Events from Spun-up Neutron Stars: an Explosion in Search of an Observation
• On the anomalous X-ray afterglows of GRB 970508 and GRB 970828

Cited by in corpus (5)

• An unexpectedly rapid decline in the X-ray afterglow emission of long gamma-ray bursts
• A complete sample of bright Swift short Gamma-Ray Bursts
• Short GRBs and Mergers of Compact Objects: Observational Constraints
• The optical afterglows and host galaxies of three short/hard gamma-ray bursts
• Completely dark galaxies: their existence, properties, and strategies for finding them