The mass distribution in the outskirts of clusters of galaxies as a probe of the theory of gravity

Abstract

We show that the radial location of the minimum in the differential radial mass profile M0(r) of a galaxy cluster, can probe the theory of gravity. We derived M0(r) of the dark matter halos of galaxy clusters from N-body cosmological simulations that implement two different theories of gravity: standard gravity in the CDM model, and f (R).We extracted 49 169 dark matter halos in 11 redshift bins in the range 0 z 1 and in three different mass bins in the range 0:9 < 11.We investigated the correlation of & with the redshift and the mass accretion rate (MAR) of the halos. We show that & decreases from 3R200c to 2R200c when z increases from 0 to 1 in the CDM model. At z 0:1, & decreases from 2:8R200c to 2:5R200c when the MAR increases from 104 h-1 M yr-1 to 2105 h-1 M yr-1. In the f (R) model, & is 15% larger than in CDM. The median test shows that for samples of 400 dark matter halos at z 0:8, & is able to distinguish between the two theories of gravity with a p-value .10-5. Upcoming advanced spectroscopic and photometric programs will allow a robust estimation of the mass profile of enormous samples of clusters up to large clustercentric distances. These samples will allow us to statistically exploit & as probe of the theory of gravity, which complements other large-scale probes.