Regular phantom black holes

TL;DR

This paper classifies regular solutions in scalar field gravity with negative kinetic energy, revealing new black hole and cosmological models with potential implications for universe creation and stability.

Contribution

It provides a comprehensive classification of regular solutions including black holes and cosmologies in scalar field theories with negative kinetic energy.

Findings

Regular black holes with de Sitter cores are possible.

Traversable wormholes and Kantowski-Sachs cosmologies are among the solutions.

Explicit examples of regular solutions are constructed and analyzed.

Abstract

For self-gravitating, static, spherically symmetric, minimally coupled scalar fields with arbitrary potentials and negative kinetic energy (favored by the cosmological observations), we give a classification of possible regular solutions to the field equations with flat, de Sitter and AdS asymptotic behavior. Among the 16 presented classes of regular rsolutions are traversable wormholes, Kantowski-Sachs (KS) cosmologies beginning and ending with de Sitter stages, and asymptotically flat black holes (BHs). The Penrose diagram of a regular BH is Schwarzschild-like, but the singularity at $r=0$ is replaced by a de Sitter infinity, which gives a hypothetic BH explorer a chance to survive. Such solutions also lead to the idea that our Universe could be created from a phantom-dominated collapse in another universe, with KS expansion and isotropization after crossing the horizon. Explicit examples of regular solutions are built and discussed. Possible generalizations include $k$-essence type scalar fields (with a potential) and scalar-tensor theories of gravity.