Neutrino and axion hot dark matter bounds after WMAP-7

We update cosmological hot dark matter constraints on neutrinos and hadronic axions. Our most restrictive limits use 7-year data from theWilkinson Microwave Anisotropy Probe for the cosmic microwave background anisotropies, the halo power spectrum (HPS) from the 7th data release of the Sloan Digital Sky Survey, and the Hubble constant from Hubble Space Telescope observations. We find 95% CL upper limits of Sigma m(v) < 0.44 eV (no axions), m(a) < 0.91 eV (assuming Sigma m(v) = 0), and Sigma m(v) < 0.41 eV and m(a) < 0.72 eV for two hot dark matter components after marginalising over the respective other mass. CMB data alone yield Sigma m(v) < 1.19 eV (no axions), while for axions the HPS is crucial for deriving ma constraints. This difference can be traced to the fact that for a given hot dark matter fraction axions are much more massive than neutrinos.