A study of background for IXPE

Focal plane X-ray polarimetry is intended for relatively bright sources with a negligible impact of background. However this might not be always possible for IXPE (Imaging X-ray Polarimetry Explorer) when observing faint extended sources like supernova remnants. We present for the first time the expected background of IXPE by Monte Carlo simulation and its impact on real observations of point and extended X-ray sources. The simulation of background has been performed by Monte Carlo based on GEANT4 framework. The spacecraft and the detector units have been modeled, and the expected background components in IXPE orbital environment have been evaluated. We studied different background rejection techniques based on the analysis of the tracks collected by the Gas Pixel Detectors on board IXPE. The estimated background is about 2.9 times larger than the requirement, yet it is still negligible when observing point like sources. Albeit small, the impact on supernova remnants indicates the need for a background subtraction for the observation of the extended sources. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study focuses on the expected background of IXPE and its impact on point and extended X-ray sources. Monte Carlo simulation was used to evaluate the background in the IXPE orbital environment, along with different background rejection techniques. The estimated background is about 2.9 times larger than the requirement, indicating the need for background subtraction when observing extended sources like supernova remnants.