The effect of Warm Dark Matter on galaxy properties: constraints from the stellar mass function and the Tully-Fisher relation

TL;DR

This study uses simulations and galaxy observations to constrain warm dark matter models, showing that certain WDM candidates are incompatible with observed galaxy properties, thus refining dark matter theories.

Contribution

It demonstrates that combining stellar mass function data with the Tully-Fisher relation can effectively constrain the properties of warm dark matter.

Findings

WDM models with m<0.75 keV fail to match observations.

Differences in the stellar mass function diminish with varied baryonic parameters.

Combining multiple observations tightens constraints on dark matter properties.

Abstract

In this paper we combine high resolution N-body simulations with a semi analytical model of galaxy formation to study the effects of a possible Warm Dark Matter (WDM) component on the observable properties of galaxies. We compare three WDM models with a dark matter mass of 0.5, 0.75 and 2.0 keV, with the standard Cold Dark Matter case. For a fixed set of parameters describing the baryonic physics the WDM models predict less galaxies at low (stellar) masses, as expected due to the suppression of power on small scales, while no substantial difference is found at the high mass end. However these differences in the stellar mass function, vanish when different set of parameters are used to describe the (largely unknown) galaxy formation processes. We show that is possible to break this degeneracy between DM properties and the parameterization of baryonic physics by combining observations on the stellar mass function with the Tully-Fisher relation (the relation between stellar mass and the rotation velocity at large galactic radii as probed by resolved HI rotation curves). WDM models with a too warm candidate (m<0.75 keV) cannot simultaneously reproduce the stellar mass function and the Tully-Fisher relation. We conclude that accurate measurements of the galaxy stellar mass function and the link between galaxies and dark matter haloes down to the very low-mass end can give very tight constraints on the nature of DM candidates.