Gravitational Properties of the Monopole Bag

TL;DR

This paper explores the gravitational behavior of a hybrid monopole and axion domain wall system, revealing possible horizon-less and black hole-like remnants with unique electromagnetic properties.

Contribution

It introduces the concept of a monopole bag in axionic cosmologies and analyzes its gravitational collapse outcomes, including regular black holes with non-trivial axionic profiles.

Findings

Both horizon-less and black hole-like states can form after gravitational collapse.

The black hole-like state is a dyonic regular black hole with exotic electromagnetic properties.

The system retains a non-trivial axionic profile, avoiding singularities.

Abstract

Axionic cosmologies constitute a class of models with phenomenologically rich symmetry breaking in the early universe. In the case where monopoles are present in such a background, the axion profile may be deformed; it is possible to construct a ``monopole bag" state composed of a central monopole within a closed axion domain wall. We consider the gravitational properties of this hybrid defect, and find a both horizon-less and a black hole-like final state can result as remnants of the monopole-domain wall system after gravitational collapse for different input parameters. We demonstrate that the latter classifies as dyonic regular black hole, evading the usual singular gravitational collapse and retaining a non-trivial axionic profile through exotic electromagnetic properties of an axionic Chern-Simons term.