Constraints on decaying Dark Matter from XMM-Newton observations of M31

TL;DR

This paper uses XMM-Newton observations of M31 to set new constraints on decaying dark matter particles, particularly sterile neutrinos, challenging some existing production scenarios and supporting their viability as dark matter candidates.

Contribution

It provides improved constraints on sterile neutrino dark matter parameters using X-ray data and compares these with cosmological bounds, ruling out certain production mechanisms.

Findings

Lower mass limit for sterile neutrinos: m_s < 4 keV.

Disfavoring the Dodelson-Widrow production scenario for sterile neutrinos.

Sterile neutrinos remain viable dark matter candidates under alternative production mechanisms.

Abstract

We derive constraints on parameters of the radiatively decaying Dark Matter (DM) particles, using XMM-Newton EPIC spectra of the Andromeda galaxy (M31). Using the observations of the outer (5'-13') parts of M31 we improve the existing constraints. For the case of sterile neutrino DM, combining our constraints with the latest computation of abundances of sterile neutrino in the Dodelson-Widrow (DW) scenario, we obtain the lower mass limit m_s < 4 keV, which is stronger than the previous one m_s < 6 kev, obtained recently by Asaka et al. (2007) [hep-ph/0612182]. Comparing this limit with the most recent results on Lyman-alpha forest analysis of Viel et al. (2007) [arXiv:0709.0131] (m_s > 5.6 kev), we argue that the scenario in which all the DM is produced via DW mechanism is ruled out. We discuss however other production mechanisms and note that the sterile neutrino remains a viable candidate of Dark Matter, either warm or cold.