Identification of the ~3.55 keV emission line candidate objects across the sky

TL;DR

This study uses wavelet analysis on XMM-Newton data to identify 235 sky regions with potential ~3.55 keV emission line candidates, aiding future investigations into its origin.

Contribution

It introduces a wavelet-based method for detecting faint X-ray emission lines across the sky, validated through simulations, and compiles a comprehensive candidate list for further analysis.

Findings

Identified 235 candidate regions for the 3.55 keV line.

Validated wavelet method with simulations on Andromeda galaxy.

Provided a candidate list for future spectral studies.

Abstract

Emission line at the energy ~3.55 keV detected in different galaxies and galaxy clusters has caused a lot of discussion in high-energy astrophysics and particle physics communities. To reveal the origin of the line, we analyzed publicly available observations of MOS cameras from XMM-Newton cosmic observatory - the instrument with the largest sensitivity for narrow faint X-ray lines - previously combined in X-ray sky maps. Because of extremely large timescale needed for detailed analysis, we used the wavelet method instead. Extensive simulations of the central part of Andromeda galaxy are used to check the validity of this method. The resulting list of wavelet detections now contains 235 sky regions. This list will be used in future works for more detailed spectral analysis.