Axion hot dark matter bounds

TL;DR

This paper establishes cosmological bounds on axion and neutrino hot dark matter components, constraining axion mass to less than 1.02 eV and neutrino mass sum to less than 0.63 eV using large-scale structure data.

Contribution

It provides the first combined cosmological limits on two-component hot dark matter including axions and neutrinos, excluding the Lyman-alpha forest data.

Findings

Axion mass m_a<1.02 eV at 95% CL.

Neutrino mass sum < 0.63 eV at 95% CL.

Constraints derived using linear regime large-scale structure data.

Abstract

We derive cosmological limits on two-component hot dark matter consisting of neutrinos and axions. We restrict the large-scale structure data to the safely linear regime, excluding the Lyman-alpha forest. We derive Bayesian credible regions in the two-parameter space consisting of m_a and sum(m_nu). Marginalizing over sum(m_nu) provides m_a<1.02 eV (95% CL). In the absence of axions the same data and methods give sum(m_nu)< 0.63 eV (95% CL).