Nonlinearities in modified gravity cosmology. II. Impacts of modified gravity on the halo properties

TL;DR

This study investigates how modified gravity affects dark matter halo properties using simulations, revealing that halo mass function and concentration are sensitive indicators of gravity deviations beyond linear growth effects.

Contribution

It introduces a parameterized model to isolate the impact of modified gravity on halo properties, providing quantitative insights into deviations from general relativity.

Findings

Halo mass function differs by 5-10% for 10% gravity deviation.

Halo concentration varies by 10-20% with gravity modifications.

Halo bias shows minimal change under modified gravity.

Abstract

The statistics of dark matter halos is an essential component of understanding the nonlinear evolution in modified gravity cosmology. Based on a series of modified gravity N-body simulations, we investigate the halo mass function, concentration and bias. We model the impact of modified gravity by a single parameter \zeta, which determines the enhancement of particle acceleration with respect to GR, given the identical mass distribution (\zeta=1 in GR). We select snapshot redshifts such that the linear matter power spectra of different gravity models are identical, in order to isolate the impact of gravity beyond modifying the linear growth rate. At the baseline redshift corresponding to z_S=1.2 in the standard \Lambda CDM, for a 10% deviation from GR(|\zeta-1|=0.1), the measured halo mass function can differ by about 5-10%, the halo concentration by about 10-20%, while the halo bias differs significantly less. These results demonstrate that the halo mass function and/or the halo concentration are sensitive to the nature of gravity and may be used to make interesting constraints along this line.