Scientific simulations and optimization of the XGIS instrument on board THESEUS

Abstract

The XGIS (X and Gamma Imaging Spectrometer) is one of the three instruments onboard the THESEUS mission (ESA M5, currently in Phase-A). Thanks to its wide field of view and good imaging capabilities, it will efficiently detect and localize gamma-ray bursts and other transients in the 2-150 keV sky, and also provide spectroscopy up to 10 MeV. Its current design has been optimized by means of scientific simulations based on a Monte Carlo model of the instrument coupled to a state-of-the-art description of the populations of long and short GRBs extending to high redshifts. We describe the optimization process that led to the current design of the XGIS, based on two identical units with partially overlapping fields of view, and discuss the expected performance of the instrument.

Gamma Ray Burst studies with THESEUS

“…We use the calibrated synthetic population (of long and short GRBs) together with the knowledge of the THE-SEUS instrumental properties to estimate the impact of the mission on GRB population studies (see [71] for further details). The power of THESEUS in detecting and localizing GRBs, and eventually providing a redshift measurement, is shown in Fig.…”