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

TL;DR

This work presents constraints on the mass of warm dark matter particles derived from the Lyman-alpha flux power spectrum of 55 high-resolution HIRES spectra, improving previous constraints by a factor of 2.2.

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.

Figures (1)

• Figure 1: Flux power spectrum of the HIRES data set at different redshifts and best fit models (solid curve) with $m_{\rm WDM} = 8$ keV and a model with $m_{\rm WDM} = 2.5$ keV (dashed curve).