The ages of stellar populations in a warm dark matter universe

Abstract

By means of a semi-analytic model of galaxy formation, we show how the local observed relation between age and galactic stellar mass is affected by assuming a DM power spectrum with a small-scale cutoff. We compare results obtained by means of both a Lambda-cold dark matter (LambdaCDM) and a Lambda-warm dark matter (LambdaWDM) power spectrum - suppressed with respect to the LambdaCDM at scales below ~ 1 Mpc. We show that, within a LWDM cosmology with a thermal relic particle mass of 0.75 keV, both the mass-weighted and the luminosity-weighted age-mass relations are steeper than those obtained within a LambdaCDM universe, in better agreement with the observed relations. Moreover, both the observed differential and cumulative age distributions are better reproduced within a LambdaWDM cosmology. In such a scenario, star formation appears globally delayed with respect to the LambdaCDM, in particular in low-mass galaxies. The difficulty of obtaining a full agreement between model results and observations is to be ascribed to our present poor understanding of baryonic physics.

11 pages, 4 figures, MNRAS, accepted

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• The Evolution of the Type Ia Supernova Luminosity Function
• Galaxy Formation in Sterile Neutrino Dark Matter Models
• The frequency of very young galaxies in the local Universe: I. A test for galaxy formation and cosmological models
• On the connection between galactic downsizing and the most fundamental galactic scaling relations
• Constraining the nature of dark matter with the star formation history of the faintest Local Group dwarf galaxy satellites
• The Epoch of Reionization in Warm Dark Matter Scenarios