Sterile neutrinos as subdominant warm dark matter

Abstract

In light of recent findings which seem to disfavor a scenario with (warm) dark matter entirely constituted of sterile neutrinos produced via the Dodelson-Widrow (DW) mechanism, we investigate the constraints attainable for this mechanism by relaxing the usual hypothesis that the relic neutrino abundance must necessarily account for all of the dark matter. We first study how to reinterpret the limits attainable from X-ray non-detection and Lyman-alpha forest measurements in the case that sterile neutrinos constitute only a fraction fs of the total amount of dark matter. Then, assuming that sterile neutrinos are generated in the early universe solely through the DW mechanism, we show how the X-ray and Lyman-alpha results jointly constrain the mass-mixing parameters governing their production. Furthermore, we show how the same data allow us to set a robust upper limit fs < 0.7 at the 2 sigma level, rejecting the case of dominant dark matter (fs = 1) at the ~ 3 sigma level.

Minor changes; added references; version accepted for publication in Phys. Rev. D

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• Dark Matter Candidates: A Ten-Point Test
• Constraints on decaying Dark Matter from XMM-Newton observations of M31
• Radiative seesaw: Warm dark matter, collider and lepton flavour violating signals
• Constraints on dark matter particles from theory, galaxy observations and N-body simulations
• Investigation on light dark matter
• Sterile neutrino dark matter in $B-L$ extension of the standard model and galactic 511 keV line
• Hidden gauginos of an unbroken U(1): Cosmological constraints and phenomenological prospects
• Small-scale structure formation properties of chilled sterile neutrinos as dark matter
• Lepton Number-Driven Sterile Neutrino Production in the Early Universe
• Delayed pulsar kicks from the emission of sterile neutrinos
• The dark matter transfer function: free streaming, particle statistics and memory of gravitational clustering
• WMAP 5-year constraints on lepton asymmetry and radiation energy density: Implications for Planck
• Free streaming in mixed dark matter
• Sterile neutrino dark matter in warped extra dimensions
• Consequences of a Pati-Salam unification of the electroweak-scale active ${\nu }_R$ model
• Sterile neutrinos and structure formation