A New Dark Matter Candidate: Non-thermal Sterile Neutrinos
نویسندگان
چکیده
Xiangdong Shi and George M. Fuller Department of Physics, University of California, San Diego, La Jolla, California 92093-0319 (December 16, 1998) We propose a new and unique dark matter candidate: ∼ 100 eV to ∼ 10 keV sterile neutrinos produced via lepton number-driven resonant MSW (Mikheyev-Smirnov-Wolfenstein) conversion of active neutrinos. The requisite lepton number asymmetries in any of the active neutrino flavors range from 10−3 to 10−1 of the photon number well within primordial nucleosynthesis bounds. The unique feature here is that the adiabaticity condition of the resonance strongly favors the production of lower energy sterile neutrinos. The resulting non-thermal (cold) energy spectrum can cause these sterile neutrinos to revert to non-relativistic kinematics at an early epoch, so that free-streaming lengths at or below the dwarf galaxy scale are possible. Therefore, the main problem associated with light neutrino dark matter candidates can be circumvented in our model.
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Comment on “A New Dark Matter Candidate: Non–thermal Sterile Neutrinos”
I point out that the sterile neutrinos suggested as candidates for “cool” Dark Matter will decay through their mixing with light neutrinos. This leads to an upper bound of about 200 keV on the mass of the sterile neutrinos, but might facilitate their detection. Recently Shi and Fuller proposed [1] a new kind of Dark Matter candidate: a sterile neutrino, with small but non–vanishing mixing with ...
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