Characterizing decaying dark matter: X-ray emission from sterile neutrinos

Abstract

Recently, an unknown emission line at E 3.5 keV from several astrophysical objects has been detected.The line is suggested to be originating from decaying dark matter particles. The results have drawn great attention fromthe astrophysics and particle physics community. Since the detected line is signi cantly weak there has also been a longdebate over the origin of this mysterious signal. The most accepted scenario is a radiatively decaying sterile neutrinoof 7.1 keV in mass producing a monochromatic 3.5 keV line, which is observable in X-ray energy ranges. The problemhas not been settled and further observations from more objects are needed to verify the detection in order to constrainthe physical properties and the nature of the signal. In this paper, we present the current situation and provide furtherinsights into the subject.