On Shear-free perturbations of f(R) gravity

Abstract

Recently it was shown that if the matter congruence of a general relativistic perfect fluid flow in an almost FLRW universe is shear-free, then it must be either expansion or rotation-free. Here we generalize this result for a general f(R) theory of gravity and show there exist scenarios where this result can be avoided. This suggests that there are situations where linearized forth-order gravity shares properties with Newtonian theory not valid in General Relativity.

6 pages, published version, no conclusions changed

References in corpus (9)

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Cited by in corpus (11)

• Black holes, cosmological solutions, future singularities, and their thermodynamical properties in modified gravity theories
• Breaking the cosmological background degeneracy by two-fluid perturbations in f(R) gravity
• Shear-free Anisotropic Cosmological Models in f(R) Gravity
• Anti-Newtonian cosmologies in f(R) gravity
• Irrotational-fluid cosmologies in fourth-order gravity
• On the Hyperbolicity and Stability of $3+1$ Formulations of Metric $f(R)$ Gravity
• Integrability conditions of quasi-Newtonian cosmologies in modified gravity
• On 1 + 3 covariant perturbations of the quasi-Newtonian space-time in modified Gauss-Bonnet gravity
• Shear-free conditions of a Chaplygin-Gas-dominated universe
• Matter shear and vorticity in conformally flat spacetimes
• Reviving The Shear-Free Perfect Fluid Conjecture In General Relativity