New Gamma-Ray Bursts Found in the Archival Data from the IBIS/ISGRI Telescope of the INTEGRAL Observatory

TL;DR

This study systematically analyzed 15 years of archival data from the INTEGRAL observatory's IBIS/ISGRI telescope, discovering seven new gamma-ray bursts and providing detailed catalogs and statistical analysis of these events.

Contribution

It presents the first systematic search for GRBs in IBIS/ISGRI archival data, identifying previously unknown bursts missed by automatic detection systems.

Findings

Seven new GRBs localized with < 2 arcmin accuracy.

Detection of 886 GRBs outside the field of view, mostly previously recorded.

Compilation of catalogs and statistical analysis of GRB parameters.

Abstract

A systematic search for cosmic gamma-ray bursts (GRBs) and other short hard X-ray events in the archival data from the IBIS/ISGRI telescope of the INTEGRAL observatory over 2003-2018 has been carried out. Seven previously unknown GRBs have been recorded in the telescope field of view; all of them have been localized with an accuracy < 2 arcmin. These events were not revealed by the INTEGRAL burst alert system (IBAS) designed for an automatic GRB search and alert. Four more such localized events missed by IBAS, but known previously, i.e., observed in other experiments, have been found. Eight hundred and eighty six GRBs outside the field of view that arrived at large angles to the IBIS/ISGRI axis have also been recorded. All of them were previously recorded in other experiments, primarily by the anticoincidence shield (ACS) of the SPI gamma-ray spectrometer onboard INTEGRAL, the PICsIT detector of the IBIS gamma-ray telescope, and the KONUS/WIND monitor. An order of magnitude more events without any confirmations in other experiments have been recorded. Both GRBs and solar flares or magnetospheric transient events can be among them. Catalogs with the basic parameters of confirmed and previously unknown GRBs recorded by IBIS/ISGRI have been compiled. The statistical distributions of bursts in various parameters have been constructed and investigated.