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arXiv · 1606.02212

Strong energy condition and the repulsive character of f(R) gravity

Crislane S. Santos·Janilo Santos·Salvatore Capozziello·Jailson S. Alcaniz
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Abstract

The Raychaudhuri equation enables to examine the whole spacetime structure without specific solutions of Einstein's equations, playing a central role for the understanding of the gravitational interaction in Cosmology. In General Relativity, without considering a cosmological constant, a non-positive contribution in the Raychaudhuri equation is usually interpreted as the manifestation of the attractive character of gravity. In this case, particular energy conditions -- indeed the strong energy condition -- must be assumed in order to guarantee the attractive character. In the context of f(R) gravity, however, even assuming the standard energy conditions one may have a positive contribution to the Raychaudhuri equation. Besides providing a simple way to explain the observed cosmic acceleration, this fact opens the possibility of a repulsive character of this kind of gravity. In order to discuss physical bounds on f(R) models, we address the attractive/non-attractive character of f(R) gravity considering the Raychaudhuri equation and assuming the strong energy condition along with recent estimates of the cosmographic parameters.

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Crislane S. Santos, Janilo Santos, Salvatore Capozziello, Jailson S. Alcaniz. 2016-06-07. Strong energy condition and the repulsive character of f(R) gravity. https://doi.org/10.1007/s10714-017-2212-0

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