Hot Dark Matter in Cosmology

TL;DR

This paper reviews the role of hot dark matter composed of neutrinos in cosmology, discussing current constraints from neutrino oscillation data and cosmological observations, and exploring the potential for future detection or tighter limits.

Contribution

It provides a comprehensive review of constraints on hot dark matter from recent neutrino and cosmological data, highlighting the limited but possible impact of light neutrinos in cosmological models.

Findings

Atmospheric neutrino oscillation data imply a lower limit on hot dark matter contribution.

Current data allow for $ u$-based hot dark matter models with $oxed{ ext{up to } ext{Ω}_ u ext{ } ext{~} 0.1}$.

Future data may detect or further constrain hot dark matter contributions.

Abstract

Cosmological dark matter in the form of neutrinos with masses of up to a few electron volts is known as hot dark matter. After an historical review of the subject, this article considers constraints on hot dark matter from current data on neutrino oscillations and on cosmology. The atmospheric neutrino oscillation data imply a lower limit on the HDM contribution to the cosmological density $\Omega_\nu \gsim 0.001$. The possible improvement of low-$\Omega_m$ flat ($\Lambda$CDM) cosmological models with the addition of light neutrinos appears to be rather limited, but$\Lambda$CDM models with $\Omega_\nu \lsim 0.1$ may be consistent with presently available data. Data expected soon may permit detection of such a hot dark matter contribution, or alternatively provide stronger upper limits on $\Omega_\nu$ and neutrino masses.