Strong bursts from the anomalous X-ray pulsar 1E 1547.0-5408 observed with the INTEGRAL/SPI Anti-Coincidence Shield

TL;DR

This paper reports on the detection of over 200 short gamma-ray bursts from the anomalous X-ray pulsar 1E 1547.0-5408 using INTEGRAL SPI-ACS, including two bright bursts with pulsating tails, revealing insights into burst energies and pulsar activity.

Contribution

First detailed analysis of gamma-ray bursts from 1E 1547.0-5408 during its active period with INTEGRAL SPI-ACS, highlighting pulsating tails and energy release levels.

Findings

Over 200 bursts detected above 80 keV during active period.

Two bright bursts showed pulsating tails modulated at 2.1 s.

Energy of brightest burst ~10^43 erg, intermediate between typical and giant flares.

Abstract

In January 2009, multiple short bursts of soft gamma-rays were detected from the direction of the anomalous X-ray pulsar 1E 1547.0-5408 by different satellites. Here we report on the observations obtained with the INTEGRAL SPI-ACS detector during the period with the strongest bursting activity. More than 200 bursts were detected at energies above 80 keV in a few hours on January 22. Among these, two remarkably bright events showed pulsating tails lasting several seconds and modulated at the 2.1 s spin period of 1E 1547.0-5408. The energy released in the brightest of these bursts was of a few 10^43 erg, for an assumed distance of 10 kpc. This is smaller than that of the three giant flares seen from soft gamma-ray repeaters, but higher than that of typical bursts from soft gamma-ray repeaters and anomalous X-ray pulsars.