Reissner Nordstrom black holes with integrable singularity interiors supported by string distributions

TL;DR

This paper proposes a model where Reissner Nordstrom black holes have an interior supported by string distributions with integrable singularities, eliminating the inner horizon and associated instabilities, and ensuring finite tidal forces.

Contribution

It introduces string-based interior models for RN black holes that remove the inner horizon and provide finite tidal forces, with explicit realizations using string clouds and fluids.

Findings

Interior models with integrable singularities are compatible with RN exterior.

String fluid models can produce finite energy configurations.

Thermal equilibrium conditions relate interior and exterior geometries.

Abstract

The Reissner Nordstrom (RN) black hole is characterized by two well known pathologies: a central singularity and an inner horizon associated with instabilities and a potential loss of predictability. In this work, we show that the RN exterior geometry can arise from an interior spacetime containing an integrable singularity but no inner horizon. In this scenario, tidal forces remain finite near the origin, allowing nondestructive radial infall, while the conventional description in terms of a pointlike mass is replaced by an extended matter distribution. To illustrate this possibility, we provide explicit realizations of such an interior region based on string distributions, namely a cloud of strings (CS) and a newly defined fluid of strings (FS). While the standard cloud of strings model leads to a divergence in the conserved energy associated with timelike Killing vectors, the proposed FS model can be interpreted as a geometrically screened version of the string cloud distribution and admits configurations that, when extended to infinity, describe black holes with finite conserved energy. Physical consistency between the interior region and the RN exterior geometry requires the continuity of temperature across the interface, implying thermal equilibrium between the two regions, while discontinuities in the tangential pressure can signal gravitational phase transitions. These results determine the physical conditions under which string based interior distributions can consistently generate the RN exterior geometry and clarify the circumstances under which phase transitions at the event horizon may arise.