Abstract
Distortions of CMB (cosmic microwave background) temperature and polarization anisotropy maps caused by gravitational lensing, observable with high angular resolution and sensitivity, can be used to constrain the sterile neutrino mass, offering several advantages over the analysis based on the combination of CMB, LSS (large scale structure) and Lyα forest power spectra. As the gravitational lensing effect depends on the matter distribution, no assumption on light-to-mass bias is required. In addition, unlike the galaxy clustering and Lyα forest power spectra, the projected gravitational potential power spectrum probes a large range of angular scales, the non-linear corrections being required only at very small scales.
Taking into account the changes in the time–temperature relation of the primordial plasma and the modification of the neutrino thermal potential, we compute the projected gravitational potential power spectrum and its correlation with the temperature in the presence of the DM (dark matter) sterile neutrino.
We show that the cosmological parameters are generally not biased when the DM sterile neutrino is included. From this analysis we found a lower limit on DM sterile neutrino mass mνs>2.08 keV at 95% CL, consistent with the lower mass limit obtained from the combined analysis of CMB, SDSS (Sloan Digital Sky Survey) 3D power spectrum and SDSS Lyα forest power spectrum (mνs>1.7 keV).
We conclude that although the information that can be obtained from lensing extraction is rather limited due to the high level of lensing noise of the PLANCK experiment, weak lensing of CMB offers a valuable alternative to constrain the dark matter sterile neutrino mass.