Regular black holes and gravitational particle-like solutions in generic DHOST theories

TL;DR

This paper constructs regular, asymptotically flat black hole solutions and particle-like configurations in higher order scalar-tensor (DHOST) theories, analyzing their properties, thermodynamics, and potential observational signatures.

Contribution

It introduces a generalized Kerr-Schild method to generate regular DHOST black holes and particle-like solutions, expanding the landscape of exact solutions in modified gravity.

Findings

Existence of regular black holes with inner and outer horizons.

Discovery of horizonless, particle-like solutions below a certain mass.

Comparison of thermodynamics between DHOST solutions and GR black holes.

Abstract

We construct regular, asymptotically flat black holes of higher order scalar tensor (DHOST) theories, which are obtained by making use of a generalized Kerr-Schild solution generating method. The solutions depend on a mass integration constant, admit a smooth core of chosen regularity, and generically have an inner and outer event horizon. In particular, below a certain mass threshold, we find massive, horizonless, particle-like solutions. We scan through possible observational signatures ranging from weak to strong gravity and study the thermodynamics of our regular solutions, comparing them, when possible, to General Relativity black holes and their thermodynamic laws.