Cosmological and Astrophysical Implications of Sterile Neutrinos

TL;DR

This paper explores the role of sterile neutrinos in cosmology and astrophysics, proposing mechanisms for their production, implications for dark matter, and effects on supernova dynamics, with a focus on their theoretical and observational significance.

Contribution

It introduces a minimal extension of the Standard Model with a singlet Higgs to produce keV sterile neutrinos and discusses their impact on dark matter and supernova explosions.

Findings

Sterile neutrinos can account for dark matter with a colder relic distribution.

The proposed Higgs mechanism operates near the electroweak scale, influencing phase transitions.

Sterile neutrinos affect supernova energy transport and explosion probability.

Abstract

The discovery of neutrino masses implies the existence of new particles, the sterile neutrinos. These particles can have important implications for cosmology and astrophysics. A sterile neutrino with mass of a few keV can account for the dark matter of the universe. Its relic abundance can be produced via different mechanisms. A minimal extension of the Higgs sector of the Standard Model, with a gauge-singlet boson coupled to sterile neutrinos, can provide a consistent framework for the theory of neutrino masses, and can produce relic keV sterile neutrinos via decays of the singlet Higgs. This mechanism operates around the electroweak scale, and has interesting consequences for the electroweak phase transition. The resulting dark matter is "colder" than the one produced via oscillations. This property changes the small-scale structure formation limits. Heavier sterile neutrinos can be produced in supernova cores and affect the thermal evolution of the star. Being short-lived, they decay inside the envelope and facilitate the energy transport from the core to the vicinity of the supernova shock. This enhances the probability for a successful explosion.