Constraining warm dark matter candidates including sterile neutrinos and light gravitinos with WMAP and the Lyman- α forest

The matter power spectrum at comoving scales of $(1\ensuremath{-}40){h}^{\ensuremath{-}1}\text{ }\text{ }\mathrm{Mpc}$ is very sensitive to the presence of Warm Dark Matter (WDM) particles with large free-streaming lengths. We present constraints on the mass of WDM particles from a combined analysis of the matter power spectrum inferred from the large samples of high-resolution high signal-to-noise Lyman-$\ensuremath{\alpha}$ forest data of Kim et al. (2004) and Croft et al. (2002) and the cosmic microwave background data of WMAP. We obtain a lower limit of ${m}_{\mathrm{WDM}}\ensuremath{\gtrsim}550\text{ }\text{ }\mathrm{eV}$ ($2\ensuremath{\sigma}$) for early decoupled thermal relics and…