Generalized energy conditions in Extended Theories of Gravity

Abstract

Theories of physics can be considered viable if the initial value problem and the energy conditions are formulated self-consistently. The former allow a uniquely determined dynamical evolution of the system, and the latter guarantee that causality is preserved and that "plausible" physical sources have been considered. In this work, we consider the further degrees of freedom related to curvature invariants and scalar fields in Extended Theories of Gravity (ETG). These new degrees of freedom can be recast as effective perfect fluids that carry different meanings with respect to the standard matter fluids generally adopted as sources of the field equations. It is thus somewhat misleading to apply the standard general relativistic energy conditions to this effective energy-momentum, as the latter contains the matter content and a geometrical quantity, which arises from the ETG considered. Here, we explore this subtlety, extending on previous work, in particular, to cases with the contracted Bianchi identities with diffeomorphism invariance and to cases with generalized explicit curvature-matter couplings, which imply the non-conservation of the energy-momentum tensor. Furthermore, we apply the analysis to specific ETGs, such as scalar-tensor gravity, $f(R)$ gravity and modified Gauss-Bonnet gravity. Interesting results appear such as matter that may exhibit unusual thermodynamical features, for instance, and gravity that retains its attractive character in the presence of negative pressures; or alternatively, we verify that repulsive gravity may occur for standard matter.

12 pages, version accepted for publication in Phys.Rev.D

References in corpus (28)

• f(R,T) gravity
• Extra force in $f(R)$ modified theories of gravity
• Extended Theories of Gravity and their Cosmological and Astrophysical Applications
• Palatini Approach to Modified Gravity: f(R) Theories and Beyond
• f(R,L_m) gravity
• Low surface brightness galaxies rotation curves in the low energy limit of $R^n$ gravity : no need for dark matter?
• Generalized curvature-matter couplings in modified gravity
• Energy conditions in f(R)-gravity
• Dark energy and dark matter as curvature effects
• Dark matter as a geometric effect in f(R) gravity
• Wormhole geometries supported by a nonminimal curvature-matter coupling
• Nonminimal curvature-matter coupled wormholes with matter satisfying the null energy condition
• Analysis of Rotation Curves in the framework of R^n gravity
• Cosmology of hybrid metric-Palatini f(X)-gravity
• Energy conditions bounds on f(T) gravity
• Generalized virial theorem in f(R) gravity
• Constraining f(R) theories with the energy conditions
• Palatini formulation of modified gravity with a nonminimal curvature-matter coupling
• Dark matter and dark energy as a effects of Modified Gravity
• Geodesic deviation, Raychaudhuri equation, and tidal forces in modified gravity with an arbitrary curvature-matter coupling
• Hidden Negative Energies in Strongly Accelerated Universes
• Energy conditions in f(R) gravity and Brans-Dicke theories
• Energy conditions in generalized teleparallel gravity models
• Generalized dark gravity
• Null Energy Condition violations in bimetric gravity
• Scalar-tensor cosmology at the general relativity limit: Jordan vs Einstein frame
• Lectures on Mathematical Cosmology
• Scalar-tensor cosmologies: general relativity as a fixed point of the Jordan frame scalar field

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• Extended Theories of Gravity in cosmological and astrophysical applications
• Constraints on Energy Conditions in $f(R,L_m)$ Gravity