  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.
