Black Holes with a Massive Dilaton

TL;DR

This paper explores how giving a mass to the dilaton field affects black hole structures, revealing conditions for the number of horizons and discussing extremal solutions and causal structures.

Contribution

It provides new constraints on the horizon structure of dilaton black holes with a massive dilaton and analyzes their causal and extremal properties.

Findings

Black holes with Qm < O(1) have only one horizon.

For Qm > O(1), solutions with three horizons may exist.

The study discusses extremal solutions and causal structures of massive dilaton black holes.

Abstract

The modifications of dilaton black holes which result when the dilaton acquires a mass are investigated. We derive some general constraints on the number of horizons of the black hole and argue that if the product of the black hole charge $Q$ and the dilaton mass $m$ satisfies $Q m < O(1)$ then the black hole has only one horizon. We also argue that for $Q m > O(1)$ there may exist solutions with three horizons and we discuss the causal structure of such solutions. We also investigate the possible structures of extremal solutions and the related problem of two-dimensional dilaton gravity with a massive dilaton.