Effects of baryons on the gravitational redshift profile of {\Lambda}CDM halos

TL;DR

This paper studies how baryonic physics influence gravitational redshift profiles in galaxy clusters, revealing significant modifications due to baryons that impact relativistic effect measurements.

Contribution

It demonstrates that baryonic processes substantially alter gravitational redshift profiles in halos, providing modified halo models and fits for better interpretation.

Findings

Baryons increase gravitational redshifts by up to 50% in group-sized halos.

Baryonic effects significantly modify inner halo density profiles.

Modified Navarro-Frenk-White profiles can parametrize baryonic impacts.

Abstract

Gravitational redshifts and other relativistic effects are beginning to be studied in the context of galaxy clustering. Distortions consistent with those expected in General Relativity have been measured in galaxy cluster redshift profiles by Wojtak et al. and others and in the the cross-correlation function of galaxy populations by Alam et al. On scales below ~20 Mpc/$h$ simulations have shown that gravitational redshift dominates over other effects. However, this signal is related to the shape and depth of gravitational potentials, and therefore the matter density in galaxies and galaxy clusters that is responsible for them. We investigate the effects of baryonic physics on the gravitational redshift profiles of massive (group and cluster-sized) halos. We compare the profiles of different components in halos taken from the MassiveBlack-II cosmological hydrodynamic simulation and a dark matter-only version of the same simulation. We find that inclusion of baryons, cooling, star formation and feedback significantly alters the relevant inner density profiles. These baryonic effects lead to overall increases in both gravitational redshifts and the transverse relativistic Doppler effects by up to ~50% for group size halos. We show how modified Navarro Frenk White halo profiles can be used to parametrize these differences, and provide relevant halo profile fits.