## Gravitational redshift profiles in the \$f(R)\$ and symmetron models    [PDF]

Max B. Grönke, Claudio Llinares, David F. Mota
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 using the code \texttt{Isis}, which includes scalar fields, to analyse the deviation of observables in modified gravity models with respect to \$\Lambda\$CDM. Results. We find that due to the presence of the screening, the deviation is highly dependent on the halo mass. For instance, the \$f(R)\$ parameters \$|f_{R0}|=10^{-5}\$, \$n=1\$ cause an enhancement of the gravitational signal by up to 50% for halos with masses between \$10^{13}\,M_\sun h^{-1}\$ and \$10^{14}\,M_\sun 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 halos are screened, there could also be a weaker gravitational redshift.
View original: http://arxiv.org/abs/1307.6994