English

Homogeneous G\"odel-type solutions in hybrid metric-Palatini gravity

General Relativity and Quantum Cosmology 2018-07-17 v3 Cosmology and Nongalactic Astrophysics

Abstract

[Abridged] If gravitation is to be described by a hybrid metric-Palatini f(R)f(\mathcal{R}) gravity theory there are a number of issues that ought to be examined in its context, including the question as to whether its equations allow homogeneous G\"odel-type solutions, which necessarily leads to violation of causality. Here, to look further into the potentialities and difficulties of f(R)f(\mathcal{R}) theories, we examine whether they admit G\"odel-type solutions for well-motivated matter source. We first show that under certain conditions on the matter sources the problem of finding out space-time homogeneous solutions in f(R)f(\mathcal{R}) theories reduces to the problem of determining solutions of Einstein's field equations with a cosmological constant. Employing this far-reaching result, we determine a general G\"odel-type whose matter source is a combination of a scalar with an electromagnetic field plus a perfect fluid. This general G\"odel-type solution contains special solutions in which the essential parameter m2m^2 can be m2>0m^{2} > 0, m=0m=0, and m2<0m^{2} < 0, covering thus all classes of homogeneous G\"odel-type spacetimes. This general solution also contains all previously known solution as special cases. The bare existence of these G\"odel-type solutions makes apparent that hybrid metric-Palatini gravity does not remedy causal anomaly in the form of closed timelike curves that are permitted in general relativity.

Keywords

Cite

@article{arxiv.1611.03985,
  title  = {Homogeneous G\"odel-type solutions in hybrid metric-Palatini gravity},
  author = {Janilo Santos and Marcelo J. Reboucas and Antônio F. F. Teixeira},
  journal= {arXiv preprint arXiv:1611.03985},
  year   = {2018}
}

Comments

V2: Presentation of Sec.4 substantially improved, references added, version published in Eur.Phys.J.C