Extended Emission from Short Gamma-Ray Bursts Detected with SPI-ACS/INTEGRAL

TL;DR

This study analyzes short gamma-ray bursts detected by INTEGRAL's SPI-ACS, revealing that a significant portion exhibit extended emission, challenging previous assumptions about their characteristics.

Contribution

It demonstrates that 30-45% of SPI-ACS short GRBs show extended emission, a higher fraction than previously believed.

Findings

Extended emission detected in averaged light curves

Fraction of short GRBs with extended emission is 30-45%

Extended emission presence challenges prior models

Abstract

The short duration (T90 < 2 s) gamma-ray bursts (GRBs) detected in the SPI-ACS experiment onboard the INTEGRAL observatory are investigated. Averaged light curves have been constructed for various groups of events, including short GRBs and unidentified short events. Extended emission has been found in the averaged light curves of both short GRBs and unidentified short events. It is shown that the fraction of the short GRBs in the total number of SPI-ACS GRBs can range from 30 to 45%, which is considerably larger than has been thought previously.