The first GRB survey of the IBIS/PICsIT archive

TL;DR

This study utilizes the PICsIT detector on INTEGRAL to identify and analyze gamma-ray bursts in the 260-2600 keV range, creating a catalog and examining spectral variability with high time resolution.

Contribution

First comprehensive survey of GRBs using PICsIT data, providing a catalog and spectral analysis in the high-energy range from 2006 to 2009.

Findings

39 GRBs identified, mostly confirmed or simultaneous with other instruments

Produced detailed light curves in three energy bands with 0.25 s resolution

Calibrated instrumental counts with external fluence measurements

Abstract

The multi-purpose INTEGRAL mission is continuously contributing to Gamma Ray Burst (GRB) science, thanks to the performances of its two main instruments, IBIS and SPI, operating in the hard X-ray/soft gamma-ray domain. We investigate the possibilities offered to the study of GRBs by PICsIT, the high-energy detector of the IBIS instrument. We searched for transient episodes in the PICsIT light curves archive from May 2006 to August 2009, using stringent criteria optimized for the detection of long events. In the time interval under examination PICsIT provides an energy coverage from 208 to 2600 keV, resolved in eight energy channels, combined with a fine time resolution of 16 ms. PICsIT successfully observes GRBs in the 260-2600 keV energy range with an incoming direction spread over half the sky for the brightest events. We compiled a list of 39 bursts, most of which are confirmed GRBs or simultaneous to triggers from other satellites/instruments. We produced light curves with a time sampling down to 0.25 s in three energy intervals for all events. Because an adequate response matrix is not yet available for the PICsIT burst sample, we obtained a calibration coefficient in three selected energy bands by comparing instrumental counts with physical fluences inferred from observations with different satellites. The good time resolution provided by the PICsIT data allows a spectral variability study of our sample through the hardness ratio.