Dilatonic interpolation between Reissner-Nordstrom and Bertotti-Robinson spacetimes with physical consequences

TL;DR

This paper explores a broad class of black hole solutions in Einstein-Maxwell-Dilaton gravity, analyzing their stability, radiation spectra, and quantum properties, revealing how dilaton parameters influence spacetime structure and physical behavior.

Contribution

It introduces a general framework for black hole solutions with dilaton fields, coupling various potentials, and studies their stability, radiation, and quantum characteristics, highlighting the role of dilaton parameters.

Findings

Dilatonic parameters determine the transition between Bertotti-Robinson and Reissner-Nordström spacetimes.

Certain black hole solutions exhibit instability under linear radial perturbations.

The study of Hawking radiation spectra reveals unique features influenced by dilaton fields.

Abstract

We give a general class of static, spherically symmetric, non-asymptotically flat and asymptotically non-(anti) de Sitter black hole solutions in Einstein-Maxwell-Dilaton (EMD) theory of gravity in 4-dimensions. In this general study we couple a magnetic Maxwell field with a general dilaton potential, while double Liouville-type potentials are coupled with the gravity. We show that the dilatonic parameters play the key role in switching between the Bertotti-Robinson and Reissner-Nordstr\"om spacetimes. We study the stability of such black holes under a linear radial perturbation, and in this sense we find exceptional cases that the EMD black holes are unstable. In continuation we give a detailed study of the spin-weighted harmonics in dilatonic Hawking radiation spectrum and compare our results with the previously known ones. Finally, we investigate the status of resulting naked singularities of our general solution when probed with quantum test particles.