The interior spacetimes of stars in Palatini f(R) gravity

Kainulainen, Kimmo; Reijonen, Vappu; Sunhede, Daniel

The interior spacetimes of stars in Palatini f(R) gravity

Authors

Kainulainen, Kimmo

Reijonen, Vappu

Sunhede, Daniel

Description

We study the interior spacetimes of stars in the Palatini formalism of f(R) gravity and derive a generalized Tolman-Oppenheimer-Volkoff and mass equation for a static, spherically symmetric star. We show that matching the interior solution with the exterior Schwarzschild-De Sitter solution in general gives a relation between the gravitational mass and the density profile of a star, which is different from the one in General Relativity. These modifications become neglible in models for which $δF(R) \equiv \partial f/\partial R - 1$ is a decreasing function of R however. As a result, both Solar System constraints and stellar dynamics are perfectly consistent with $f(R) = R - μ^4/R$.
Published version, 6 pages, 1 figure