Direct x-ray constraints on sterile neutrino warm dark matter
Citations Over TimeTop 1% of 2006 papers
Abstract
Warm dark matter might more easily account for small scale clustering measurements than the heavier particles typically invoked in $\ensuremath{\Lambda}$ cold dark matter ($\ensuremath{\Lambda}\mathrm{CDM}$) cosmologies. In this paper, we consider a $\ensuremath{\Lambda}\mathrm{WDM}$ cosmology in which sterile neutrinos ${\ensuremath{\nu}}_{s}$, with a mass ${m}_{s}$ of roughly 1--100 keV, are the dark matter. We use the diffuse x-ray spectrum (total minus resolved point source emission) of the Andromeda galaxy to constrain the rate of sterile neutrino radiative decay: ${\ensuremath{\nu}}_{s}\ensuremath{\rightarrow}{\ensuremath{\nu}}_{e,\ensuremath{\mu},\ensuremath{\tau}}+\ensuremath{\gamma}$. Our findings demand that ${m}_{s}<3.5\text{ }\text{ }\mathrm{keV}$ (95% C.L.) which is a significant improvement over the previous (95% C.L.) limits inferred from the x-ray emission of nearby clusters, ${m}_{s}<8.2\text{ }\text{ }\mathrm{keV}$ (Virgo A) and ${m}_{s}<6.3\text{ }\text{ }\mathrm{keV}$ ($\mathrm{\text{Virgo}}\text{ }\mathrm{A}+\mathrm{\text{Coma}}$).