Rotating black holes in semiclassical gravity

TL;DR

This paper introduces new analytic rotating black hole solutions in semiclassical gravity influenced by trace anomaly, revealing unique features like non-circular horizons and violations of the Kerr bound.

Contribution

It provides the first analytic solutions for rotating black holes in semiclassical gravity with trace anomaly, linking them to specific Horndeski theories and exploring their properties.

Findings

Black holes exhibit non-circularity and non-spherical horizons.

Solutions violate the classical Kerr bound.

Existence domain of these black holes is characterized.

Abstract

We present analytic stationary and axially-symmetric black hole solutions to the semiclassical Einstein equations that are sourced by the trace anomaly. We also find that the same spacetime geometry satisfies the field equations of a subset of Horndeski theories featuring a conformally coupled scalar field. We explore various properties of these solutions, and determine the domain of existence of black holes. These black holes display distinctive features, such as non-circularity, a non-spherically symmetric event horizon and violations of the Kerr bound.