Slowly Rotating Black Holes in Einsteinian Quartic Gravities

TL;DR

This paper investigates slowly rotating black holes in six Einsteinian Quartic Gravity theories, revealing distinct solutions for most theories and analyzing their physical properties like shadows and orbits.

Contribution

It extends the study of rotating black holes to Einstein Quartic Gravity, deriving second-order equations and providing approximate and numerical solutions.

Findings

Distinct solutions for five out of six theories

Modified black hole properties such as shadow and orbit

Reduction to second-order equations for rotating solutions

Abstract

We study slowly rotating black hole solutions in the six independent theories of Einstein Quartic Gravity (EQG) in four dimensions. Unlike in the static case for which all six theories yield the same solution, for rotating black holes we obtain distinct results for five out of the six theories. Working to leading order in the rotation parameter, we find that the equations characterizing these black holes can be reduced to second order for each theory, similar to what has already been done for Einstein Cubic Gravity. We construct approximate and numerical solutions to these equations, and study how physical properties of the solutions such as the angular velocity, photon sphere, black hole shadow, and innermost stable circular orbit are modified, working to leading order in the coupling constant.