Thermalizing Sterile Neutrino Dark Matter

Area of Science:

• Cosmology
• Particle Physics
• Astrophysics

Background:

• Sterile neutrinos are a motivated dark matter candidate.
• Observational constraints have significantly limited viable parameter space for sterile neutrinos.
• Existing models face tensions with structure formation and X-ray observations.

Purpose of the Study:

• To analyze the impact of new interactions on keV sterile neutrino dark matter evolution.
• To investigate a mechanism that thermalizes sterile neutrinos in the early Universe.
• To resolve current observational tensions and revive sterile neutrino dark matter production models.

Main Methods:

• Analysis of sterile neutrino evolution under new interactions.
• Introduction of a thermalization mechanism post-oscillation production.
• Investigation of energy and entropy conservation principles.

Main Results:

• A mechanism that thermalizes sterile neutrinos after oscillation production was identified.
• Dark entropy production accompanying thermalization increases dark matter yield.
• Lower characteristic momentum of sterile neutrinos resolves observational tensions.
• Nonresonant sterile neutrino production is revived as a viable dark matter production method.

Conclusions:

• New interactions and a thermalization mechanism can resolve current challenges for sterile neutrino dark matter.
• The proposed mechanism successfully addresses tensions with structure formation and X-ray data.
• Simple nonresonant production is re-established as a viable pathway for sterile neutrino dark matter.