The Swift Discovery of X-Ray Afterglows Accompanying Short Bursts from SGR 1900+14

Abstract

The discovery of X-ray afterglows accompanying two short bursts from SGR 1900+14 is presented. The afterglow luminosities at the end of each observation are lower by 30%-50% than their initial luminosities, and decay with power-law indices p~0.2-0.4. Their initial bolometric luminosities are L~1034-1035 erg s-1. We discuss analogies and differences between the X-ray afterglows of SGR short bursts and short gamma-ray bursts.