Hybrid Metric-Palatini Gravity: Black Holes, Wormholes, Singularities, and Instabilities

Abstract: The hybrid metric-Palatini theory of gravity (HMPG), proposed in 2012 by T. Harko et al., is known to successfully describe both local (solar-system) and cosmological observations. We discuss static, spherically symmetric vacuum solutions of HMPG with the aid of its scalar-tensor theory (STT) representation. This scalar-tensor theory coincides with general relativity with a conformally coupled scalar field (which can be canonical or phantom), therefore the known solutions of this theory are re-interpreted in terms of HMPG. In particular, in the case of zero scalar field potential V(Φ), such that both Riemannian and Palatini Ricci scalars are zero, generic asymptotically flat solutions either contain naked singularities or describe traversable wormholes, and there are only special cases of black hole solutions with extremal horizons. There is also a one-parameter family of solutions with an infinite number of extremal horizons between static regions. Examples of analytical solutions with nonzero potentials V(Φ) are also described, among them black hole solutions with simple horizons which are generic but, for canonical scalars, they require (at least partly) negative potentials. With phantom scalars there are “black universe” solutions that lead beyond the horizon to an expanding universe instead of a singularity. Most of the solutions under consideration turn out to be unstable under scalar monopole perturbations, but some special black hole solutions are stable. © 2020, Pleiades Publishing, Inc.

Authors
Number of issue
3
Language
English
Pages
212-227
Status
Published
Volume
26
Year
2020
Organizations
  • 1 Center for Gravitation and Fundamental Metrology, VNIIMS, Ozyornaya ul. 46, Moscow, 119361, Russian Federation
  • 2 Institute of Gravitation and Cosmology, RUDN University, ul. Miklukho-Maklaya 6, Moscow, 117198, Russian Federation
  • 3 National Research Nuclear University “MEPhI,”, Kashirskoe sh. 31, Moscow, 115409, Russian Federation
Date of creation
02.11.2020
Date of change
02.11.2020
Short link
https://repository.rudn.ru/en/records/article/record/64569/