A&A 471, 51-57 (2007)
Constraints on the parameters of radiatively decaying dark matter from the dark matter halos of the Milky Way and Ursa MinorA. Boyarsky1, 2, 3, J. Nevalainen4, and O. Ruchayskiy5, 2
1 CERN, PH-TH, 1211 Geneve 23, Switzerland
2 École Polytechnique Fédérale de Lausanne, Institute of Theoretical Physics, FSB/ITP/LPPC, BSP 720, 1015 Lausanne, Switzerland
3 Bogolyubov Institute of Theoretical Physics, Kyiv, Ukraine
4 Helsinki University Observatory, Finland
5 Institut des Hautes Études Scientifiques, 91440 Bures-sur-Yvette, France
(Received 20 November 2006 / Accepted 19 April 2007)
Aims.We improve the earlier restrictions on parameters of the warm dark matter (DM) in the form of a sterile neutrinos.
Methods.The results were obtained from not observing the DM decay line in the X-ray spectrum of the Milky Way (using the recent XMM-Newton PN blank sky data). We also present a similar constraint coming from the recent XMM-Newton observation of Ursa Minor - dark, X-ray quiet dwarf spheroidal galaxy.
Results.The new Milky way data improve on (by as much as the order of magnitude at masses ~3.5 keV) existing constraints. Although the observation of Ursa Minor has relatively poor statistics, the constraints are comparable to those recently obtained using observations of the Large Magellanic Cloud or M 31. This confirms a recent proposal that dwarf satellites of the MW are very interesting candidates for the DM search and dedicated studies should be made to this purpose.
Key words: Galaxy: halo -- galaxies: individual: Ursa Minor -- cosmology: dark matter -- X-rays: galaxies
© ESO 2007