1810.08629
Quantifying baryon effects on the matter power spectrum and the weak lensing shear correlation
Schneider, Teyssier, Stadel, Chisari, Le Brun, Amara, Refregier
Feedback processes from baryons are expected to strongly affect weak-lensing observables of current and future cosmological surveys. In this paper, present a new parameterization of halo profiles based on gas, stellar, and DM density components. This parameterization is then used to modify outputs of gravity-only N-body simulations (following the prescriptions of Schneider and Teyssier) in order to mimic baryon effects on the matter density field. The resulting baryon correction model relies on a few well motivated physical parameters and is able to reproduce the clustering signal of hydrodynamical sims at 3% accuracy or better at z=0. A detailed study of the baryon suppression effects on the matter PS and the WL shear correlation reveals that the signal is dominated by 2 parameters describing the slope of the gas profile in haloes and the maximum radius of gas ejection. Show that these parameters can be constrained with the observed gas fraction of galaxy groups and clusters from X-ray data. Based on these observations, predict a beyond percent effect on the power spectrum above k=0.2=1.0 h/Mpc with a maximum suppression of 15-25 percent around k~10 h/Mpc. As a result, the weak lensing angular shear power spectrum is suppressed by 10-20 % at scales beyond ell~200-1000 and the shear correlations xi_+ and xi_- are affected at the 10-25 % level below 5 and 50 arcminutes, respectively. The relatively large uncertainties of these predictions are a result of the poorly known hydrostatic mass bias of current X-ray observations as well as the generic difficulty to observe the low density gas outside of haloes.
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