The Soft X-ray Imager on board EXIST

TL;DR

The Soft X-ray Imager (SXI) on board the EXIST observatory is designed to perform broadband X-ray observations, surveys, and transient monitoring, enhancing the study of high-energy astrophysical sources like AGNs and GRBs with unprecedented sensitivity.

Contribution

This paper introduces the SXI instrument on EXIST, detailing its capabilities for broadband X-ray observations and its role in high-energy astrophysics research.

Findings

SXI will provide broadband coverage from 0.1 to 600 keV.

It will enable detailed spectral and variability studies of AGNs and GRBs.

The instrument will conduct sky surveys with high sensitivity.

Abstract

The Soft X-ray Imager (SXI) is one of the three instruments on board EXIST, a multi-wavelength observatory in charge of performing a global survey of the sky in hard X-rays searching for Super-massive Black Holes (Grindlay & Natalucci, these Proceedings). One of the primary objectives of EXIST is also to study with unprecedented sensitivity the most unknown high energy sources in the Universe, like high redshift GRBs, which will be pointed promptly by the Spacecraft by autonomous trigger based on hard X-ray localization on board. The presence of a soft X-ray telescope with an effective area of about 950cm2 in the energy band 0.2-3 keV and extended response up to 10 keV will allow to make broadband studies from 0.1 to 600 keV. In particular, investigations of the spectra components and states of AGNs and monitoring of variability of sources, study of the prompt and afterglow emission of GRBs since the early phases, which will help to constrain the emission models and finally, help the identification of sources in the EXIST hard X-ray survey and the characterization of the transient events detected. SXI will also perform surveys: a scanning survey with sky coverage 2pi and a limiting flux of 5x10^(-14) cgs plus other serendipitous.