MaGICC-WDM: the effects of warm dark matter in hydrodynamical simulations of disc galaxy formation

TL;DR

This study investigates how warm dark matter influences hydrodynamical simulations of disc galaxy formation, finding minimal effects for WDM particle masses above 2 keV, with star formation and galaxy structure largely unaffected.

Contribution

It provides the first detailed comparison of galaxy formation under different WDM candidates using hydrodynamical simulations within the MaGICC project.

Findings

WDM slightly reduces star formation in simulations.

Galaxy disc properties remain largely unchanged across WDM models.

Effects are most significant for 1 keV WDM, negligible above 2 keV.

Abstract

We study the effect of warm dark matter (WDM) on hydrodynamic simulations of galaxy formation as part of the Making Galaxies in a Cosmological Context (MaGICC) project. We simulate three different galaxies using three WDM candidates of 1, 2 and 5 keV and compare results with pure cold dark matter simulations. WDM slightly reduces star formation and produces less centrally concentrated stellar profiles. These effects are most evident for the 1 keV candidate but almost disappear for $m_{\mathrm{WDM}}>2$ keV. All simulations form similar stellar discs independent of WDM particle mass. In particular, the disc scale length does not change when WDM is considered. The reduced amount of star formation in the case of 1 keV particles is due to the effects of WDM on merging satellites which are on average less concentrated and less gas rich. The altered satellites cause a reduced starburst during mergers because they trigger weaker disc instabilities in the main galaxy. Nevertheless we show that disc galaxy evolution is much more sensitive to stellar feedback than it is to WDM candidate mass. Overall we find that WDM, especially when restricted to current observational constraints ($m_{\mathrm{WDM}}>2$ keV), has a minor impact on disc galaxy formation.