Determination of the Solar System contribution to the soft X-ray sky

TL;DR

This study quantifies the solar wind charge exchange contribution to the soft X-ray sky using eROSITA data, enabling clearer observation of the diffuse X-ray background and mapping interstellar matter flow.

Contribution

It provides the first detailed measurement of SWCX effects in eROSITA X-ray data, improving the understanding of foreground contamination in soft X-ray observations.

Findings

SWCX contribution was quantified and subtracted from eROSITA data.

The cleaned data offers a clearer view of the diffuse soft X-ray sky.

X-ray observations can trace interstellar matter flow through the Solar System.

Abstract

Solar wind charged particles interact with diffuse gas within the heliosphere, producing soft X-rays. This solar wind charge exchange (SWCX) process produces foreground emission that complicates interpretation of X-ray observations. In this work, we analyze X-ray observations of the western Galactic hemisphere by the Extended Roentgen Survey with an Imaging Telescope Array (eROSITA) instrument on the Spectrum-Roentgen-Gamma (SRG) spacecraft. These data avoid contamination by Earth's geocorona and are derived from four surveys of the full sky, including during the minimum of the Sun's activity cycle. We determine the SWCX contribution and subtract it from the survey, providing a less contaminated view of the diffuse soft X-ray sky. We also demonstrate that X-rays can be used to map the flow of interstellar matter through the Solar System.