Where do the 3.5 keV photons come from? A morphological study of the Galactic Center and of Perseus

TL;DR

This study investigates the origin of 3.5 keV photons in the Galactic Center and Perseus cluster, finding their distribution inconsistent with dark matter decay and instead linked to astrophysical processes.

Contribution

The paper provides the first detailed morphological analysis of 3.5 keV emission, offering the most stringent constraints on dark matter decay lines in this energy range.

Findings

3.5 keV emission does not match dark matter distribution

Galactic Center 3.5 keV photons follow other line emissions

Perseus 3.5 keV photons correlate with the cool core

Abstract

We test the origin of the 3.5 keV line photons by analyzing the morphology of the emission at that energy from the Galactic Center and from the Perseus cluster of galaxies. We employ a variety of different templates to model the continuum emission and analyze the resulting radial and azimuthal distribution of the residual emission. We then perform a pixel-by-pixel binned likelihood analysis including line emission templates and dark matter templates and assess the correlation of the 3.5 keV emission with these templates. We conclude that the radial and azimuthal distribution of the residual emission is incompatible with a dark matter origin for both the Galactic center and Perseus; the Galactic center 3.5 keV line photons trace the morphology of lines at comparable energy, while the Perseus 3.5 keV photons are highly correlated with the cluster's cool core, and exhibit a morphology incompatible with dark matter decay. The template analysis additionally allows us to set the most stringent constraints to date on lines in the 3.5 keV range from dark matter decay.