Gravitational redshift profiles in the f(R) and symmetron models

Abstract

Aims: We investigate the gravitational redshift in clusters of galaxies in the symmetron and Hu-Sawicky f(R) models. The characteristic feature of both models is the screening mechanism that hides the fifth force in dense environments recovering general relativity. Methods: We use N-body simulations that were run with the code Isis, which includes scalar fields, to analyse the deviation of observables in modified gravity models with respect to ΛCDM. Results: We find that the presence of the screening makes the deviation highly dependent on the halo mass. For instance, the f(R) parameters | fR0 | = 10-5, n = 1 cause an enhancement of the gravitational signal by up to 50% for haloes with masses between 1013 M⊙ h-1 and 1014 M⊙ h-1. The characteristic mass range where the fifth force is most active varies with the model parameters. The usual assumption is that the presence of a fifth force leads to a deeper potential well and thus a stronger gravitational redshift. However, we find that in cases in which only the central regions of the haloes are screened, there could also be a weaker gravitational redshift. Reproduced with permission from Astronomy & Astrophysics, © ESO