Black holes and covariance in effective quantum gravity: A solution without Cauchy horizons

Abstract

The issue of general covariance in effective quantum gravity models within the Hamiltonian framework is addressed. The previously proposed equations for the covariance condition in spherically symmetric models are explicitly derived. By solving this equation, a new effective Hamiltonian constraint is obtained, incorporating free functions that can account for quantum gravity effects. The resulting spacetime structure is analyzed by specifying the free functions. Remarkably, in this model, the classical singularity is replaced by a region where the metric asymptotically approaches a Schwarzschild-de Sitter one with negative mass. Thus, this new quantum-corrected black hole model avoids the Cauchy horizons presented typically in previously studied models. The covariant approach is also applicable to matter coupling in the models.

14+4 pages, 3 figures. Revisions in v3: Clarified the presentation to improve readability and overall understanding of the manuscript. Major revisions in v2: Relaxed the ansatz used in the previous version and proposed sufficient and necessary conditions for general covariance, from which a more general form of the effective Hamiltonian constraint is derived