98 citations · 441 across the 26 of their papers we have counts for
27 papers
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…
Vacuum polarization and renormalized stress-energy tensor of spherical thin shells
Julio Arrechea, Cormac Breen, Adrian Ottewill +2
We provide a thorough study of the properties of the Boulware vacuum in the spacetime of a spherical, static thin shell with a Minkowski interior. To this end, we calculate the ren…
Cone hierarchy and the screening of matter by gravity
Julio Arrechea, Carlos Barceló, Gil Jannes
In a previous paper by some of the authors (Gen. Rel. Grav. 56, 116, 2024), we introduced a novel paradigm with which to understand gravitational phenomena. We called it the Harmon…
Effective geometrostatics of spherical stars beyond general relativity
Julio Arrechea, Raúl Carballo-Rubio, Matt Visser
We provide a set of general tools to study the problem of stellar equilibrium in any gravitational theory in which spherically symmetric spacetimes satisfy master field equations 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…
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…
Beyond Buchdahl's limit: bilayered stars and thin-shell configurations
Julio Arrechea, Carlos Barceló, Gerardo García-Moreno +1
One of the theoretical motivations behind the belief that black holes as described by general relativity exist in nature is that it is hard to find matter configurations that mimic…
The renormalized stress-energy tensor for scalar fields in the Boulware state with applications to extremal black holes
Julio Arrechea, Cormac Breen, Adrian Ottewill +2
We provide a mode-sum prescription to directly compute the renormalized stress-energy tensor (RSET) for scalar fields in the Boulware vacuum. The method generalizes the recently de…
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…
Ultracompact horizonless objects in order-reduced semiclassical gravity
Julio Arrechea, Carlos Barceló, Raúl Carballo-Rubio +1
The backreaction of quantum fields in their vacuum state results in equilibrium structures that surpass the Buchdahl compactness limit. Such backreaction is encapsulated in the vac…
After collapse: On how a physical vacuum can change the black hole paradigm
Julio Arrechea, Carlos Barceló, Valentin Boyanov
Standard General Relativity assumes that, in the absence of classical matter sources, spacetime is empty. This chapter considers and analyses the new behaviours of the gravitationa…
Renormalized stress-energy tensor for scalar fields in Hartle-Hawking, Boulware and Unruh states in the Reissner-Nordström spacetime
Julio Arrechea, Cormac Breen, Adrian Ottewill +1
In this paper, we consider a quantum scalar field propagating on the Reissner-Nordström black hole spacetime. We compute the renormalized stress-energy tensor for the field in the…
Stellar equilibrium on a physical vacuum soil
Julio Arrechea, Carlos Barceló
We show that the repulsive effects associated to the zero-point energies of quantum fields are capable of supporting ultracompact stars that overcome the compactness limits present…
Asymptotically flat vacuum solutions in order-reduced semiclassical gravity
Julio Arrechea, Carlos Barceló, Raúl Carballo-Rubio +1
We investigate the effects of quantum backreaction on the Schwarzschild geometry in the semiclassical approximation. The renormalized stress-energy tensor (RSET) of a scalar field…
Breaking Buchdahl: ultracompact stars in semiclassical gravity
Julio Arrechea, Carlos Barceló, Raúl Carballo-Rubio +1
The semiclassical approximation takes into account the gravitational contribution of zero-point energies. We model this contribution via the renormalized stress-energy tensor (RSET…
Semiclassical relativistic stars
Julio Arrechea, Carlos Barceló, Raúl Carballo-Rubio +1
We present strong evidence that semiclassical gravity can give place to self-consistent ultracompact stars beyond the Buchdahl limit. We integrate the semiclassical equations of (s…
Semiclassical constant-density spheres in a regularized Polyakov approximation
Julio Arrechea, Carlos Barceló, Raúl Carballo-Rubio +1
We provide an exhaustive analysis of the complete set of solutions of the equations of stellar equilibrium under semiclassical effects. As classical matter we use a perfect fluid o…
Reissner-Nordström geometry counterpart in semiclassical gravity
Julio Arrechea, Carlos Barceló, Raúl Carballo-Rubio +1
We compute the Renormalized Stress-Energy Tensor (RSET) of a massless minimally coupled scalar field in the Regularized Polyakov approximation, as well as its backreaction, on the…
Inversion of statistics and thermalization in the Unruh effect
Julio Arrechea, Carlos Barceló, Luis J. Garay +1
We derive a master equation for the reduced density matrix of a uniformly accelerating quantum detector in arbitrary dimensions, generically coupled to a field initially in its vac…
Vacuum semiclassical gravity does not leave space for safe singularities
Julio Arrechea, Carlos Barceló, Valentin Boyanov +1
General relativity predicts its own demise at singularities, but also appears to conveniently shield itself from the catastrophic consequences of such singularities, making them sa…