Subdominant Dark Matter sterile neutrino resonant production in the light of PLANCK

Few independent detections of a weak X-ray line at an energy of similar to 3.5 keV seen toward a number of astrophysical sites have been reported. If this signal will be confirmed to be the signature of decaying DM sterile neutrino with a mass of similar to 7.1 keV, then the cosmological observables should be consistent with its properties. In this paper we make a coupled treatment of the weak decoupling, primordial nucleosynthesis and photon decoupling epochs in the sterile neutrino resonant production scenario, including the extra radiation energy density via N-eff. We compute the radiation and matter perturbations including the full resonance sweep solution for nu(alpha)/(nu) over bar (alpha) -> nu(s) flavor conversion in the expanding Universe. We show that the cosmological measurements are in agreement with subdominant Dark Matter sterile neutrino resonant production with following parameters (errors at 95% CL): mass m(nu s) = 6.08 +/- 3.22 keV, mixing angle sin(2) 2 theta < 5.61 x 10(-10), lepton number per flavor L-4 = 1.23 +/- 0.04 (L-4 equivalent to 10(4) L-nu alpha) and sterile neutrino mass fraction f(nu s) < 0.078. Our results are in good agreement with the sterile neutrino resonant production parameters inferred in ref. [62] from the linear large scale structure constraints to produce full Dark Matter density.