Black Strings in Ho\v{r}ava-Lifshitz Gravity

TL;DR

This paper explores black string solutions in Hořava-Lifshitz gravity, revealing the existence of BTZ type black strings without sources and analyzing their properties, including rotation, mass, angular momentum, and entropy.

Contribution

It introduces new BTZ type black string solutions in Hořava-Lifshitz gravity, including static and rotating cases, and compares their properties to those in general relativity.

Findings

BTZ type black strings exist in HL gravity without sources

Rotating BTZ black strings require nonzero radial shift

Entropy of static BTZ black string is half of horizon area

Abstract

We examine a class of cylindrically symmetric solutions in Horava-Lifshitz gravity. For the relativistic value of the coupling constant, $ \lambda=1 $, we find the "hedgehog" type static black string solution with the nonvanishing radial shift in the ADM-type decomposition of the spacetime metric. With zero radial shift, this solution corresponds to the usual BTZ black string in general relativity. However, unlike the general relativity case, the BTZ type black strings do naturally exist in HL gravity, without the need for any specific source term. We also find a rotating BTZ type black string solution which requires the nonvanishing radial shift for its very existence. We calculate the mass and the angular momentum of this solution, using the canonical Hamiltonian approach. Next, we discuss the Lemos type black string, which is inherent in general relativity with a negative cosmological constant, and present the static metric for any value of $ \lambda > 1/3 $. Finally, we show that while, for $\lambda=1 $, the entropy of the Lemos type black string is given by one quarter of the horizon area, the entropy of the static BTZ type black string is one half of its horizon area.