X-raying extended emission and rapid decay of short gamma-ray bursts

Understand

Extended emission is a mystery in short gamma-ray bursts (SGRBs).

• By making time resolved spectral analyses of brightest nine events observed by ${\it Swift}$ XRT, we obviously classify the early X-ray emission of SGRBs into two types.
• One is the extended emission with exponentially rapid decay, which shows significant spectral softening during hundreds seconds since the SGRB trigger and is also detected by ${\it Swift}$-BAT.
• The other is a dim afterglow only showing power-law decay over $10^4$ s.