Sterile Neutrino as Dark Matter candidate from CMB alone

Distortions of CMB temperature and polarization maps caused by gravitational lensing, observable with high angular resolution and sensitivity, can be used to constrain the sterile neutrino mass, m_s, from CMB data alone. We forecast m_s>1.75 keV from Planck and m_s>4.97 keV from Inflation Probe at 95% CL, by using the CMB weak lensing extraction.