Halo mass function: Baryon impact, fitting formulae and implications for cluster cosmology

Understand

We use a set of hydrodynamical (Hydro) and dark matter only (DMonly) simulations to calibrate the halo mass function (HMF).

• We explore the impact of baryons, propose an improved parametrization for spherical overdensity masses and identify differences between our DMonly HMF and previously published HMFs.
• We use the \textit{Magneticum} simulations, which are well suited because of their accurate treatment of baryons, high resolution, and large cosmological volumes of up to $(3818~\textrm{Mpc})^3$.
• Baryonic effects globally decrease the masses of galaxy clusters, which, at a given mass, results in a decrease of their number density.