Clustering properties of a sterile neutrino dark matter candidate
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States)
The clustering properties of sterile neutrinos are studied within a simple extension of the minimal standard model, where these neutrinos are produced via the decay of a gauge singlet scalar. The distribution function after decoupling is strongly out of equilibrium and features an enhancement at small comoving momentum {proportional_to}1/{radical}(p). Dark matter abundance and phase space density constraints from dwarf spheroidal galaxies constrain the mass in the keV range consistent with a Yukawa coupling to a gauge singlet with mass and vacuum expectation value in the range {approx}100 GeV and a decoupling temperature of this order. The dark matter transfer function and power spectrum are obtained from the solution of the nonrelativistic Boltzmann-Vlasov equation in the matter dominated era. The small momentum enhancement of the nonequilibrium distribution function leads to long range memory of gravitational clustering and a substantial enhancement of the power spectrum at small scales as compared to a thermal relic or sterile neutrino produced via nonresonant mixing with active neutrinos. The scale of suppression of the power spectrum for a sterile neutrino with m{approx}keV produced by scalar decay that decouples at {approx}100 GeV is {lambda}{approx}488 kpc. At large scales T(k){approx}1-Ck{sup 2}/k{sub fs}{sup 2}(t{sub eq})+{center_dot}{center_dot}{center_dot} with C{approx}O(1). At small scales 65 kpc < or approx. {lambda} < or approx. 500 kpc corrections to the fluid description and memory of gravitational clustering become important, and we find T(k){approx_equal}1.902e{sup -k/k{sub fs}(t{sub eq})}, where k{sub fs}(t{sub eq}){approx}0.013/kpc is the free-streaming wave vector at matter-radiation equality. The enhancement of power at small scales may provide possible relief to the tension between the constraints from x-ray and Lyman-{alpha} forest data.
- OSTI ID:
- 21250880
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 78, Issue 10; Other Information: DOI: 10.1103/PhysRevD.78.103505; (c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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