Dark MaGICC: The effect of dark energy on disc galaxy formation. Cosmology does matter

Abstract

We present the Dark MaGICC (Making Galaxies in a Cosmological Context) project, which aims to investigate the effect of dark energy (DE) modelling on disc galaxy formation via hydrodynamical cosmological simulations. Dark MaGICC includes four dynamical DE scenarios with time varying equations of state, one with a self-interacting Ratra-Peebles model. In each scenario, we simulate three disc galaxies with high resolution using smoothed particle hydrodynamics. The baryonic physics model is the same used in the MaGICC project, and we varied only the background cosmology. We find that the DE parametrization has a surprisingly important impact on galaxy evolution and on structural properties of galaxies at z = 0, in striking contrast with predictions from pure N-body simulations. The different background evolutions can (depending on the behaviour of the DE equation of state) either enhance or quench star formation with respect to a {n-ary logical and} cold dark matter model, at a level similar to the variation of the stellar feedback parametrization, with strong effects on the final galaxy rotation curves. While overall stellar feedback is still the driving force in shaping galaxies, we show that the effect of the DE parametrization plays a larger role than previously thought, especially at lower redshifts. For this reason, the influence of DE parametrization on galaxy formation must be taken into account, especially in the era of precision cosmology. © 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.