3 research outputs found
Constraints on decaying Dark Matter from XMM-Newton observations of M31
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.Comment: 13 pages, 12 figure
Constraining DM properties with SPI
Using the high-resolution spectrometer SPI on board the International
Gamma-Ray Astrophysics Laboratory (INTEGRAL), we search for a spectral line
produced by a dark matter(DM) particle with a mass in the range 40keV < M_DM <
14MeV, decaying in the DM halo of the Milky Way. To distinguish the DM decay
line from numerous instrumental lines found in the SPI background spectrum, we
study the dependence of the intensity of the line signal on the offset of the
SPI pointing from the direction toward the Galactic Centre. After a critical
analysis of the uncertainties of the DM density profile in the inner Galaxy, we
find that the intensity of the DM decay line should decrease by at least a
factor of 3 when the offset from the Galactic Centre increases from 0 to 180
degrees. We find that such a pronounced variation of the line flux across the
sky is not observed for any line, detected with a significance higher than 3
sigma in the SPI background spectrum. Possible DM decay origin is not ruled out
only for the unidentified spectral lines, having low (~3 sigma) significance or
coinciding in position with the instrumental ones. In the energy interval from
20 keV to 7 MeV, we derive restrictions on the DM decay line flux, implied by
the (non-)detection of the DM decay line. For a particular DM candidate, the
sterile neutrino of mass MDM, we derive a bound on the mixing angle.Comment: Minor changes; v.2 - Final version appeared in MNRA