A further study on Palatini f(R)-theories for polytropic stars

Abstract

After briefly reviewing the results about polytropic stars in Palatini f(R)-theories, we first show how these results rely on the assumption of a regular function f(R). In particular, singular models allow to extend the parameter interval in which no singularity is formed. Furthermore, we present how the conformal metric can be matched smoothly in the cases where the original metric generates a singularity. In fact, the singularity comes from a singular conformal factor which is continuous though not differentiable at the stellar surface. This suggests that the correct metric to be considered as physical is the conformal metric. This is relevant because, even also when matching the original metric is possible, the use of the conformal metric generates different stellar models.

18 pages (refs added and typos corrected)

References in corpus (4)

• Metric-affine f(R) theories of gravity
• A no-go theorem for polytropic spheres in Palatini f(R) gravity
• Re-examination of Polytropic Spheres in Palatini f(R) Gravity
• Extended Gravity

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• Constraining the Schwarzschild-de Sitter Solution in Models of Modified Gravity
• White dwarf stars in modified gravity
• Parameterized non-relativistic limit of stellar structure equations in Ricci-based gravity theories
• Extended Cosmology in Palatini f(R)-theories
• Invariant quantities of Scalar-Tensor Theories for stellar structure
• The Palatini star: exact solutions of the modified Lane-Emden equation
• Rotating Killing horizons in generic $F(R)$ gravity theories
• Solar System Tests in Brans-Dicke and Palatini f(R)-theories
• The effective Equation of State in Palatini $f(R)$ cosmology
• On the existence of static spherically-symmetric objects in action-dependent Lagrangian theories
• Hubble drift in Palatini $f(\mathcal{R})$-theories