Solar system tests of Ho\v{r}ava-Lifshitz gravity

TL;DR

This paper investigates whether Hořava-Lifshitz gravity, a quantum gravity candidate, can be tested within the Solar System by analyzing classical tests of general relativity, and finds that observational data can constrain its parameters.

Contribution

It applies classical Solar System tests to a spherically symmetric solution of Hořava-Lifshitz gravity to assess its observational viability and constrain its free parameters.

Findings

Classical tests can be explained by the Hořava-Lifshitz solution.

Observational data constrains the free parameter of the theory.

Hořava-Lifshitz gravity remains consistent with current Solar System observations.

Abstract

Recently, a renormalizable gravity theory with higher spatial derivatives in four dimensions was proposed by Ho\v{r}ava. The theory reduces to Einstein gravity with a non-vanishing cosmological constant in IR, but it has improved UV behaviors. The spherically symmetric black hole solutions for an arbitrary cosmological constant, which represent the generalization of the standard Schwarzschild-(A)dS solution, has also been obtained for the Ho\v{r}ava-Lifshitz theory. The exact asymptotically flat Schwarzschild type solution of the gravitational field equations in Ho\v{r}ava gravity contains a quadratic increasing term, as well as the square root of a fourth order polynomial in the radial coordinate, and it depends on one arbitrary integration constant. The IR modified Ho\v{r}ava gravity seems to be consistent with the current observational data, but in order to test its viability more observational constraints are necessary. In the present paper we consider the possibility of observationally testing Ho\v{r}ava gravity at the scale of the Solar System, by considering the classical tests of general relativity (perihelion precession of the planet Mercury, deflection of light by the Sun and the radar echo delay) for the spherically symmetric black hole solution of Ho\v{r}ava-Lifshitz gravity. All these gravitational effects can be fully explained in the framework of the vacuum solution of the gravity. Moreover, the study of the classical general relativistic tests also constrain the free parameter of the solution.