Tests of Modified gravity

• Thermal Sunyaev-Zeldovich to probe f(R)-gravity

The thermal Sunyaev-Zeldovich (tSZ) profile of clusters of galaxies can be used to constrain Extended Theories of Gravity. Models that introduce corrections to the Newtonian potential in the weak field limit can explain the dynamics of spiral and elliptical galaxies without resorting to Dark Matter (DM). Assuming that the hot intracluster gas is in hydrostatic equilibrium within the potential well of the modified gravitational field. The tSZ profile can be numerically computed to be compared with data [1].

We focused on testing the Yukawa-like gravitational potential, that is obtained in the weak field limit f(R) and MOdified Gravity (MOG) theories to the SZ profile of Coma cluster measured using the Planck data. Coma cluster has also been used to probe the assumption of universality of the weak field limit of MOG theory. I demonstrated that with such assumption MOG theory can not explain the SZ emission of galaxy clusters. On the contrary, SZ flux can be predicted varying the parameter of the theory [2, 3].