The Influence of Baryons on the Clustering of Matter and Weak-Lensing Surveys

Abstract

Future weak lensing measurements of cosmic shear will reach such high accuracy that second order effects in weak lensing modeling, like the influence of baryons on structure formation, become important. We use a controlled set of state of the art cosmological simulations to quantify this effect by comparing pure N-body dark matter runs with corresponding hydrodynamical simulations, carried out both in non-radiative, and in dissipative form with cooling and star formation. In both hydrodynamical simulations, the clustering of the gas is suppressed while that of dark matter is boosted at scales k>1 h/Mpc. Despite this counterbalance between dark matter and gas, the clustering of the total matter is suppressed by up to 1 percent at 1 <1000, but by 1 to 10 percent at 1000