Dark Matter Sterile Neutrino from Scalar Decays

We place constraints on DM sterile neutrino scalar decay production (SDP) assuming that sterile neutrinos representa fraction from the total Cold Dark Matter energy density. For the cosmological analysis we complement the CMB anisotropy measurements with CMB lensing gravitational potential measurements, that are sensitive to the DM distribution to high redshifts and with the cosmic shear data that constrain the gravitational potential at lower redshifts than CMB. We also use the most recent low-redshift BAO measurements that are insensitive to the non-linear effects, providing robust geometrical tests. We show that our datasets have enough sensitivity to constrain the sterile neutrino mass mνs and the mass fraction fS inside the co-moving free-streaming horizon. We find that the best fit value mνs=7.88±0.73 keV (68% CL) is in the parameter space of interest for DM sterile neutrino decay interpretation of the 3.5 keV X-ray line and that fS=0.86±0.07 (68% CL) is in agreement with the upper limit constraint on fS from the X-ray non-detection and Ly-α forest measurements that rejects fS=1 at 3σ. However, we expect that the future BAO and weak lensing surveys, such as EUCLID, will provide much more robust constraints