Sterile Neutrino Dark Matter from Freeze-In

TL;DR

This paper reviews the freeze-in production mechanism for sterile neutrino dark matter, highlighting its motivations, characteristics, and potential observational signatures as an alternative to the ruled-out Dodelson-Widrow scenario.

Contribution

It provides a comprehensive overview of the freeze-in mechanism for sterile neutrino dark matter, emphasizing its theoretical motivations and phenomenological implications.

Findings

Freeze-in mechanism can produce viable sterile neutrino dark matter.

It offers distinctive phenomenological signatures compared to other production methods.

The mechanism remains consistent with current astrophysical constraints.

Abstract

A sterile neutrino is a well-motivated and widely studied dark matter candidate. The most straightforward realization of sterile neutrino dark matter, through the Dodelson-Widrow mechanism, is now ruled out by a combination of X-ray and Lyman-\alpha measurements. An alternative production mechanism that is becoming increasingly popular in the literature is the freeze-in mechanism, involving frameworks where a feeble coupling to a particle - usually a scalar beyond the Standard Model - in the thermal bath results in a gradual accumulation of the sterile neutrino dark matter abundance. This article reviews the various motivations for realizing such frameworks in the literature, their common characteristic features, and phenomenological signatures.