Probing the Nature of Short Swift Bursts via Deep INTEGRAL Monitoring of GRB 050925

TL;DR

This study investigates the nature of short GRB 050925 using multi-instrument observations, suggesting it may be a soft gamma-ray repeater with unique spectral and temporal properties, and explores its possible galactic origin.

Contribution

The paper provides the first detailed multi-wavelength analysis of GRB 050925, proposing it as a candidate SGR with distinct spectral and temporal features, and discusses its potential association with galactic regions.

Findings

GRB 050925 has a blackbody spectral shape with 97% significance.

Two X-ray counterparts show transient behavior with shallow decay.

No hard X-ray emission detected in 5 Ms of INTEGRAL data.

Abstract

We present results from Swift, XMM-Newton, and deep INTEGRAL monitoring in the region of GRB 050925. This short Swift burst is a candidate for a newly discovered soft gamma-ray repeater (SGR) with the following observational burst properties: 1) galactic plane (b=-0.1 deg) localization, 2) 150 msec duration, and 3) a blackbody rather than a simple power-law spectral shape (with a significance level of 97%). We found two possible X-ray counterparts of GRB 050925 by comparing the X-ray images from Swift XRT and XMM-Newton. Both X-ray sources show the transient behavior with a power-law decay index shallower than -1. We found no hard X-ray emission nor any additional burst from the location of GRB 050925 in ~5 Ms of INTEGRAL data. We discuss about the three BATSE short bursts which might be associated with GRB 050925, based on their location and the duration. Assuming GRB 050925 is associated with the H II regions (W 58) at the galactic longitude of l=70 deg, we also discuss the source frame properties of GRB 050925.