Spherically symmetric spacetimes in f(R) gravity theories

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dc.creatorKainulainen, Kimmo
dc.creatorPiilonen, Johanna
dc.creatorReijonen, Vappu
dc.creatorSunhede, Daniel
dc.date2007-04-20
dc.date2008-03-07
dc.date.accessioned2026-07-07T10:59:42Z
dc.date.available2026-07-07T10:59:42Z
dc.descriptionWe study both analytically and numerically the gravitational fields of stars in f(R) gravity theories. We derive the generalized Tolman-Oppenheimer-Volkov equations for these theories and show that in metric f(R) models the Parameterized Post-Newtonian parameter $γ_{\rm PPN} = 1/2$ is a robust outcome for a large class of boundary conditions set at the center of the star. This result is also unchanged by introduction of dark matter in the Solar System. We find also a class of solutions with $γ_{\rm PPN} \approx 1$ in the metric $f(R)=R-μ^4/R$ model, but these solutions turn out to be unstable and decay in time. On the other hand, the Palatini version of the theory is found to satisfy the Solar System constraints. We also consider compact stars in the Palatini formalism, and show that these models are not inconsistent with polytropic equations of state. Finally, we comment on the equivalence between f(R) gravity and scalar-tensor theories and show that many interesting Palatini f(R) gravity models can not be understood as a limiting case of a Jordan-Brans-Dicke theory with $ω\to -3/2$.
dc.descriptionPublished version, 12 pages, 7 figures
dc.identifierhttps://arxiv.org/abs/0704.2729
dc.identifierhttp://arxiv.org/abs/0704.2729
dc.identifierPhys.Rev.D76:024020,2007
dc.identifierdoi:10.1103/PhysRevD.76.024020
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/187490
dc.subjectGeneral Relativity and Quantum Cosmology
dc.subjectAstrophysics
dc.subjectHigh Energy Physics - Theory
dc.titleSpherically symmetric spacetimes in f(R) gravity theories
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