How cold is cold dark matter? Small scales constraints from the flux power spectrum of the high-redshift Lyman-alpha forest

TL;DR

This paper constrains the mass of warm dark matter particles using high-redshift Lyman-alpha forest data, significantly improving previous limits and distinguishing between thermal relics and sterile neutrinos.

Contribution

It provides new, tighter bounds on warm dark matter particle masses from flux power spectrum analysis of high-redshift Lyman-alpha data, including SDSS data.

Findings

Lower limit of 1.2 keV for thermal relics (2 sigma)

Lower limit of 5.6 keV for sterile neutrinos (2 sigma)

Combined data yields limits of 4 keV and 28 keV respectively

Abstract

We present constraints on the mass of warm dark matter (WDM) particles derived from the Lyman-alpha flux power spectrum of 55 high- resolution HIRES spectra at 2.0 < z < 6.4. From the HIRES spectra, we obtain a lower limit of mwdm > 1.2 keV 2 sigma if the WDM consists of early decoupled thermal relics and mwdm > 5.6 keV (2 sigma) for sterile neutrinos. Adding the Sloan Digital Sky Survey Lyman-alpha flux power spectrum, we get mwdm > 4 keV and mwdm > 28 keV (2 sigma) for thermal relics and sterile neutrinos. These results improve previous constraints by a factor two.