Testing primordial non-gaussianities on galactic scales at high redshift

Abstract

Primordial non-Gaussianities provide an important test of inflationary models. Although the Planck cosmic microwave background experiment has produced strong limits on non- Gaussianity on scales of clusters, there is still room for considerable non-Gaussianity on galactic scales. We have tested the effect of local non-Gaussianity on the high-redshift galaxy population by running five cosmological N-body simulations down to z = 6.5. For these simulations, we adopt the same initial phases, and either Gaussian or scale-dependent non- Gaussian primordial fluctuations, all consistent with the constraints set by Planck on cluster scales.We then assign stellarmasses to each halo using the halo-stellarmass empirical relation of Behroozi et al. Our simulations with non-Gaussian initial conditions produce halo mass functions that show clear departures from those obtained from the analogous simulations with Gaussian initial conditions at z ≳ 10. We observe a >0.3 dex enhancement of the low end of the halo mass function, which leads to a similar effect on the galaxy stellar mass function, which should be testable with future galaxy surveys at z > 10. As cosmic reionization is thought to be driven by dwarf galaxies at high redshift, our findings may have implications for the reionization history of the Universe.