A White Paper on keV Sterile Neutrino Dark Matter

TL;DR

This comprehensive review discusses keV-scale sterile neutrino dark matter, covering theoretical motivations, observational constraints, model building, and future experimental searches across cosmology, astrophysics, and particle physics.

Contribution

It provides an integrated overview of sterile neutrino dark matter, combining insights from multiple disciplines and proposing future directions for research and detection.

Findings

Constraints from astrophysical observations limit sterile neutrino parameter space.

X-ray signals may indicate sterile neutrino decay, but are not conclusive.

Models beyond the Standard Model can produce keV sterile neutrinos as dark matter candidates.

Abstract

We present a comprehensive review of keV-scale sterile neutrino Dark Matter, collecting views and insights from all disciplines involved - cosmology, astrophysics, nuclear, and particle physics - in each case viewed from both theoretical and experimental/observational perspectives. After reviewing the role of active neutrinos in particle physics, astrophysics, and cosmology, we focus on sterile neutrinos in the context of the Dark Matter puzzle. Here, we first review the physics motivation for sterile neutrino Dark Matter, based on challenges and tensions in purely cold Dark Matter scenarios. We then round out the discussion by critically summarizing all known constraints on sterile neutrino Dark Matter arising from astrophysical observations, laboratory experiments, and theoretical considerations. In this context, we provide a balanced discourse on the possibly positive signal from X-ray observations. Another focus of the paper concerns the construction of particle physics models, aiming to explain how sterile neutrinos of keV-scale masses could arise in concrete settings beyond the Standard Model of elementary particle physics. The paper ends with an extensive review of current and future astrophysical and laboratory searches, highlighting new ideas and their experimental challenges, as well as future perspectives for the discovery of sterile neutrinos.