60 citations · 145 across the 20 of their papers we have counts for
22 papers
Asymptotic AEther Misalignment and Universal-Horizon Mechanics
Walter Arata, Moustafa Ismail, Stefano Liberati +3
Universal horizons trap even arbitrarily fast signals, providing a test of black-hole thermodynamics in theories with a preferred time direction. In Einstein--aether theory, this d…
Phenomenology of dynamical trapped regions
Julio Arrechea, Stefano Liberati, Hooman Neshat +1
Regular black holes (RBHs) and horizonless black hole mimickers (BHMs) are often studied as stationary alternatives to classical black holes, although their interiors may be unstab…
Semiclassical Black Hole-White Hole transitions: an analytical treatment
Julio Arrechea, Stefano Liberati, Massimiliano Spadafora
Recent numerical studies of semiclassical gravity suggest that, in spherically symmetric black holes with both outer and inner horizons, the semiclassical instability of the inner…
A parity selection rule for regular black holes
Farid Thaalba, Julio Arrechea, Stefano Liberati
Regular black hole metrics are usually studied kinematically, but a finite-curvature static core does not guarantee that the underlying theory can consistently evolve generic matte…
Off-shell equivalence in quantum field theory and gravity
Iberê Kuntz, Stefano Liberati
Field redefinitions connect many formulations of the same physics, but the standard equivalence theorem is an on-shell result and cannot be used to decide when two quantum descript…
Semiclassical regularity of compact trapped regions: From dynamical horizons to inner extremality
Raúl Carballo-Rubio, Francesco Di Filippo, Stefano Liberati +1
In eternal black-hole spacetimes, inner horizons are Cauchy horizons and are generically unstable. For non-extremal inner horizons, this includes both the classical mass-inflation…
Einstein-aether Elliptic Charges and the First Law of Asymptotically AdS Black Holes
Walter Arata, Moustafa Ismail, Stefano Liberati +3
We investigate the thermodynamic role of asymptotic aether alignment for universal horizons in Einstein-aether theory. In the static, spherically symmetric, asymptotically AdS sect…
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…
Taming the Aretakis instability: extremal black holes with multi-degenerate horizons
Shreyansh Agrawal, Panagiotis Charalambous, Laura Donnay +2
Stationary black hole geometries with non-degenerate Cauchy horizons are classically unstable due to mass inflation. At extremality, mass inflation is absent, but a different dynam…
Analog regular black holes and black hole mimickers for surface-gravity waves in fluids
Valentin Pomakov, Stefano Liberati
Recent advances in the observation of black-hole candidates have renewed interest in probing their near-horizon structure and in searching for departures from the standard singular…
A Covariant Phase Space Approach to Einstein-AEther Gravity
Walter Arata, Stefano Liberati, Giulio Neri
Black hole thermodynamics in Lorentz-violating gravity is subtle because different excitations propagate at different speeds and hence identify different causal horizons. We revisi…
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…
From de Sitter to anti-de Sitter singularity regularization: Theory and phenomenology
Julio Arrechea, Stefano Liberati, Hooman Neshat +1
Recent investigations of vacuum polarization in extremely compact stars suggest that, in such regimes, the effective matter content of spacetime may acquire a vacuum-energy equatio…
Physical and Theoretical Challenges to Integrable Singularities
Julio Arrechea, Stefano Liberati, Hooman Neshat +1
Black hole spacetimes that exhibit integrable singularities have gained considerable interest as alternatives to both regular and singular black holes. Unlike most known regular bl…
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…
Inner horizon instability via the trace anomaly effective action
Julio Arrechea, Giulio Neri, Stefano Liberati
In quantum field theory applied to black hole spacetimes, substantial evidence suggests that the Unruh and Hartle-Hawking vacuum states become singular at Cauchy horizons. This rai…
Whispers from the quantum core: the ringdown of semiclassical stars
Julio Arrechea, Stefano Liberati, Vania Vellucci
This investigation delves into the ringdown signals produced by semiclassical stars, which are ultra-compact, regular solutions of the Einstein equations incorporating stress-energ…
Covariant phase space analysis of Lanczos-Lovelock gravity with boundaries
Giulio Neri, Stefano Liberati
This work introduces a novel prescription for the expression of the thermodynamic potentials associated with the couplings of a Lanczos-Lovelock theory. These potentials emerge in…
Geodesically complete universes
Raúl Carballo-Rubio, Stefano Liberati, Vania Vellucci
Singularity theorems demonstrate the inevitable breakdown of the concept of continuous, classical spacetime under highly general conditions. Quantum gravity is expected to interven…
Kerr Black Hole in Einstein--Æther Gravity
Edgardo Franzin, Stefano Liberati, Jacopo Mazza
While non-rotating black-hole solutions are well known in Einstein--æther gravity, no axisymmetric solutions endowed with Killing horizons have been so far found outside of the slo…
From regular black holes to horizonless objects: quasi-normal modes, instabilities and spectroscopy
Edgardo Franzin, Stefano Liberati, Vania Vellucci
We study gravitational and test-field perturbations for the two possible families of spherically symmetric black-hole mimickers that smoothly interpolate between regular black hole…