Spherically Symmetric Quantum Horizons

TL;DR

This paper explores quantum horizons under spherical symmetry, revealing how horizon degrees of freedom relate to orientation and fluctuations, and examining the horizon area as a quantum observable without matter.

Contribution

It introduces a method to impose isolated horizon conditions at the quantum level specifically for spherical symmetry, advancing understanding of horizon degrees of freedom and matter effects.

Findings

Horizon degrees of freedom are linked to orientation and fluctuations.

Horizon area acts as an approximate quantum observable without matter.

Matter fields help probe the Hamiltonian constraint in quantum geometry.

Abstract

Isolated horizon conditions specialized to spherical symmetry can be imposed directly at the quantum level. This answers several questions concerning horizon degrees of freedom, which are seen to be related to orientation, and its fluctuations at the kinematical as well as dynamical level. In particular, in the absence of scalar or fermionic matter the horizon area is an approximate quantum observable. Including different kinds of matter fields allows to probe several aspects of the Hamiltonian constraint of quantum geometry that are important in inhomogeneous situations.