60 citations · 214 across the 23 of their papers we have counts for
21 papers · 1 filter
On mass inflation and late-time divergences in limiting-curvature regular black holes
Johanna Borissova
Mass inflation in non-extremal regular black holes with a non-linear dependence of the Misner-Sharp mass on the asymptotic mass may be a transient phenomenon followed by…
Formation of extremal regular black holes
Johanna Borissova
Static and slowly evolving regular black holes with a non-extremal inner horizon are generally expected to suffer from mass inflation. Here we consider the scenario of asymptotic g…
Null geodesic defocusing in dynamical black-hole-to-white-hole transitions
Johanna Borissova, Stefano Liberati, Matt Visser
We investigate the defocusing of null geodesics in dynamical, non-singular black-hole-to-white-hole transitions. Working at the level of spacetime kinematics, and without assuming…
black hole thermodynamics in general quasi-topological gravity
Johanna Borissova
We present a unified framework for the discussion of black hole thermodynamics of -dimensional static black holes with spherical or compact hyperbolic horizon topology satisfyin…
Modified Friedmann equations and non-singular cosmologies in non-polynomial quasi-topological gravities
Johanna Borissova, João Magueijo
Quasi-topological theories of gravity are known to resolve black-hole singularities. We investigate whether the same mechanism can remove cosmological singularities. Focusing on no…
Regular black holes from pure gravity in four dimensions
Johanna Borissova, Raúl Carballo-Rubio
We derive static spherically symmetric regular black holes as vacuum solutions to purely gravitational theories in four dimensions. To that end, we construct four-dimensional non-p…
Effective geometrodynamics for renormalization-group improved black-hole spacetimes in spherical symmetry
Johanna Borissova, Raúl Carballo-Rubio
We consider the spherically reduced Einstein-Hilbert action, Einstein field equations and Schwarzschild spacetime modified by a renormalization-group (RG) scale-dependent gravitati…
Spherically symmetric solutions in quasi-local Einstein-Weyl gravity
Johanna Borissova, Breno L. Giacchini, Aaron Held
Quantum-gravitational effective actions with higher-derivative and non-local operators are expected to regularize the singularities of general relativity. Here we focus on quasi-lo…
Quantum dynamics and thermodynamics of a Minkowski-Minkowski wormhole
Johanna Borissova, João Magueijo
We consider the path-integral quantization of a minisuperspace cut-and-paste Lorentzian wormhole connecting two Minkowski spacetimes. The dynamics of the throat radius as a functio…
Timelike convergence condition in regular black-hole spacetimes with (anti-)de Sitter core
Johanna Borissova, Stefano Liberati, Matt Visser
The Hawking-Penrose (1970) singularity theorem weakens the causality assumption of global hyperbolicity used in the Penrose (1965) singularity theorem, at the expense of invoking t…
Renormalization group flows in area-metric gravity
Johanna Borissova, Bianca Dittrich, Astrid Eichhorn +1
We put forward the first analysis of renormalization group flows in an area-metric theory, motivated by spin-foam quantum gravity. Area-metric gravity contains the well-known lengt…
Violations of the null convergence condition in kinematical transitions between singular and regular black holes, horizonless compact objects, and bounces
Johanna Borissova, Stefano Liberati, Matt Visser
How do regular black holes evade the Penrose singularity theorem? Various models of stationary regular black holes globally satisfy the null convergence condition (NCC). At first g…
Towards a Non-singular Paradigm of Black Hole Physics
Raúl Carballo-Rubio, Francesco Di Filippo, Stefano Liberati +18
The study of regular black holes and black hole mimickers as alternatives to standard black holes has recently gained significant attention, driven both by the need to extend gener…
Spikes and spines in 4D Lorentzian simplicial quantum gravity
Johanna Borissova, Bianca Dittrich, Dongxue Qu +1
Simplicial approaches to quantum gravity such as quantum Regge calculus and spin foams include configurations where bulk edges can become arbitrarily large while the boundary edges…
Spikes and spines in 3D Lorentzian simplicial quantum gravity
Johanna Borissova, Bianca Dittrich, Dongxue Qu +1
Simplicial approaches to quantum gravity such as Quantum Regge Calculus and Spin Foams include configurations where bulk edges can become arbitrarily large while keeping the length…
Area-metric gravity revisited
Johanna N. Borissova, Bianca Dittrich, Kirill Krasnov
Area metrics are an intriguing generalization of length metrics which appears in several quantum-gravity approaches. We describe the space of diffeomorphism-invariant area-metric a…
Suppression of spacetime singularities in quantum gravity
Johanna Borissova
We investigate the requirement of suppressing spacetime geometries with a curvature singularity via destructive interference in the Lorentzian gravitational path integral as a cons…
Formation and evaporation of quantum black holes from the decoupling mechanism in quantum gravity
Johanna N. Borissova, Alessia Platania
We propose a new method to account for quantum-gravitational effects in cosmological and black hole spacetimes. At the core of our construction is the "decoupling mechanism": when…
Towards effective actions for the continuum limit of spin foams
Johanna N. Borissova, Bianca Dittrich
Spin foams arise from a quantization of classical gravity expressed via the Plebanski action. Key open questions related to the continuum limit of spin foams are whether general re…
Scale-invariance at the core of quantum black holes
Johanna N. Borissova, Aaron Held, Niayesh Afshordi
We study spherically-symmetric solutions to a modified Einstein-Hilbert action with Renormalization Group scale-dependent couplings, inspired by Weinberg's Asymptotic Safety scenar…
Towards black-hole singularity-resolution in the Lorentzian gravitational path integral
Johanna N. Borissova, Astrid Eichhorn
Quantum Gravity is expected to resolve the singularities of classical General Relativity. Based on destructive interference of singular spacetime-configurations in the path integra…