Scalarized Kerr-Newman Black Holes

TL;DR

This paper constructs and analyzes scalarized Kerr-Newman black holes in Einstein-Maxwell-scalar models, revealing how scalarization depends on spin and the existence of multiple light rings, with implications for black hole stability.

Contribution

It introduces scalarized Kerr-Newman black hole solutions with non-minimal couplings, exploring their domain of existence and stability properties, which is a novel extension in black hole scalarization studies.

Findings

Scalarized Kerr-Newman black holes exist below a maximum spin threshold.

Multiple light rings, including unstable and stable ones, can occur in these solutions.

Scalarization is suppressed at high black hole spins.

Abstract

In this paper, we construct scalarized rotating black holes within the framework of Einstein-Maxwell-scalar models. These models incorporate non-minimal couplings that can induce tachyonic instabilities, leading to the spontaneous scalarization of Kerr-Newman (KN) black holes. By exploring the domain of existence, we observe that the presence of scalarized KN black holes is suppressed by the black hole spin, with a maximum spin threshold beyond which scalarized solutions cease to exist. Intriguingly, we find that in specific parameter regimes, scalarized KN black holes can exhibit the presence of two unstable and one stable light rings on the equatorial plane, manifesting in both prograde and retrograde directions.