Collapsing spherical stars in f(R) gravity

Abstract

We perform a careful investigation of the problem of physically realistic gravitational collapse of massive stars in f(R)-gravity. We show that the extra matching conditions that arise in the modified gravity imposes strong constraints on the stellar structure and thermodynamic properties. In our opinion these constraints are unphysical. We prove that no homogeneous stars with non-constant Ricci scalar can be matched smoothly with a static exterior for any nonlinear function f(R). Therefore, these extra constraints make classes of physically realistic collapse scenarios in general relativity, non-admissible in these theories. We also find an exact solution for an inhomogeneous collapsing star in the Starobinski model that obeys all the energy and matching conditions. However, we argue that such solutions are fine-tuned and unstable to matter perturbations. Possible consequences on black hole physics and the cosmic censorship conjecture are also discussed.

11 pages, 8 figures, Revtex 4, Minor changes in text, Matches the accepted version in Physical Review D

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• Charged strange star model in Tolman-Kuchowicz spacetime in the background of 5D Einstein-Maxwell-Gauss-Bonnet gravity
• Gravitationally collapsing stars in $f(R)$ gravity
• Cosmological model with time varying deceleration parameter in $F(R,G)$ gravity
• Charged Anisotropic Tolman IV Solution in Matter-Geometry Coupled Theory
• Compact Objects admitting Finch-Skea Symmetry in $f(\mathcal{R},T^2)$ Gravity
• Is gravitational collapse possible in $f(R)$ gravity?
• Gravitational collapse of massless scalar field in $f(R)$ gravity
• Gravitational collapse in f(R) gravity for a spherically symmetric spacetime admitting a homothetic Killing vector
• Scalar Field Collapse with an exponential potential
• Compact stars admitting Finch-Skea symmetry in the presence of various matter fields
• Geodesic Congruences and a Collapsing Stellar Distribution in f (T ) Theories
• Gravitational Collapse in Repulsive $R+{\mu }^4/R$ Gravity
• Is scalar-tensor gravity consistent with polytropic stellar models?