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

Kimmo Kainulainen·Vappu Reijonen·Daniel Sunhede
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Abstract

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 $f(R) = R - μ^4/R$.

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Kimmo Kainulainen, Vappu Reijonen, Daniel Sunhede. 2008-03-07. The interior spacetimes of stars in Palatini f(R) gravity. https://doi.org/10.1103/physrevd.76.043503

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