Probing the nature of dark matter through the metal enrichment of the intergalactic medium

We focus on exploring the metal enrichment of the intergalactic medium (IGM) in cold and warm (1.5 and 3 keV) dark matter (DM) cosmologies, and the constraints this yields on the DM particle mass, using a semi-analytic model, DELPHI, that jointly tracks the DM and baryonic assembly of galaxies at z similar or equal to 4-20 including both supernova (SN) and (a range of) reionization feedback (models). We find that while M-UV greater than or similar to -15 galaxies contribute half of all IGM metals in the cold dark matter (CDM) model by z similar or equal to 4.5, given the suppression of low-mass haloes, larger haloes with M-UV greater than or similar to -15 provide about 80 per cent of the IGM metal budget in 1.5 keV warm dark matter (WDM) models using two different models for the metallicity of the interstellar medium. Our results also show that the only models compatible with two different high-redshift data sets, provided by the evolving ultraviolet luminosity function (UV LF) at z similar or equal to 6-10 and IGM metal density, are standard CDM and 3 keV WDM that do not include any reionization feedback; a combination of the UV LF and the Diaz et al. point provides a weaker constraint, allowing CDM and 3 and 1.5 keV WDM models with SN feedback only, as well as CDM with complete gas suppression of all haloes with v(circ) less than or similar to 30 km s(-1). Tightening the error bars on the IGM metal enrichment, future observations, at z greater than or similar to 5.5, could therefore represent an alternative way of shedding light on the nature of DM.