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Late vacuum choice and slow roll approximation in gravitational particle production during reheating
Jose A. R. Cembranos, Luis J. Garay, Álvaro Parra-López +1
In the transition between inflation and reheating, the curvature scalar typically undergoes oscillations which have significant impact on the density of gravitationally produced pa…
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…
Warp Drive Aerodynamics
Carlos Barceló, Valentin Boyanov, Luis J. Garay +2
In this work we analyse the potential for a warp drive spacetime to develop instabilities due to the presence of quantum matter. Particularly, we look for points of infinite bluesh…
Causal structure of accelerating black holes
Jose A. R. Cembranos, Luis J. Garay, Sergio A. Ortega
Accelerating black holes are described by the so-called C-metric. In this work, we analyse the causal structure of such black holes by using null geodesics. We construct explicitly…
Unimodular Gravity vs General Relativity: A status report
Raúl Carballo-Rubio, Luis J. Garay, Gerardo García-Moreno
Unimodular Gravity is an alternative to General Relativity (GR) which, however, is so closely related to the latter that one can wonder to what extent they are different. The diffe…
Noether charge formalism for Weyl invariant theories of gravity
Ana Alonso-Serrano, Luis J. Garay, Marek Liška
Gravitational theories invariant under transverse diffeomorphisms and Weyl transformations have the same classical solutions as the corresponding fully diffeomorphism invariant the…
Noether charge formalism for Weyl transverse gravity
Ana Alonso-Serrano, Luis J. Garay, Marek Liška
Weyl transverse gravity is a gravitational theory that is invariant under transverse diffeomorphisms and Weyl transformations. It is characterised by having the same classical solu…
Classical mass inflation vs semiclassical inner horizon inflation
Carlos Barceló, Valentin Boyanov, Raúl Carballo-Rubio +1
We analyse the geometry of a spherically symmetric black hole with an inner and outer apparent horizon which is perturbed by spherical null shells of matter. On a classical level w…
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…
Toward a mechanism for the emergence of gravity
Carlos Barceló, Raúl Carballo-Rubio, Luis J. Garay +1
One of the main problems that emergent-gravity approaches face is explaining how a system that does not contain gauge symmetries ab initio might develop them effectively in some re…
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…
Analogue gravity simulation of superpositions of spacetimes
Carlos Barceló, Luis J. Garay, Gerardo García-Moreno
Taking the principles of quantum mechanics as they stand and applying them to gravity, leads to the conclusion that one might be able to generate superpositions of spacetimes, at l…
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…
Black hole inner horizon evaporation in semiclassical gravity
Carlos Barceló, Valentin Boyanov, Raúl Carballo-Rubio +1
In this work we analyse the backreaction of a quantum field on a spherically symmetric black hole geometry with an inner horizon, i.e. an internal boundary of the trapped region. W…
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…
Interpretations and naturalness in the radiation-reaction problem
Carlos Barceló, Luis J. Garay, Jaime Redondo-Yuste
After more than a century of history, the radiation-reaction problem in classical electrodynamics still surprises and puzzles new generations of researchers. Here we revise and exp…
Asymptotic horizon formation, spacetime stretching and causality
Carlos Barceló, Valentin Boyanov, Raúl Carballo-Rubio +1
In this work we analyse asymptotically flat, spherically symmetric spacetimes in which an event horizon is present without any trapped surfaces. We identify two types of such space…
Schwarzschild geometry counterpart in semiclassical gravity
Julio Arrechea, Carlos Barceló, Raúl Carballo-Rubio +1
We investigate the effects of vacuum polarization on vacuum static spherically-symmetric spacetimes. We start from the Polyakov approximation to the renormalized stress-energy tens…
Semiclassical gravity effects near horizon formation
Carlos Barceló, Valentin Boyanov, Raúl Carballo-Rubio +1
We study the magnitude of semiclassical gravity effects near the formation of a black-hole horizon in spherically-symmetric spacetimes. As a probe for these effects we use a quanti…
Ergoregion instability of a rotating quantum system
Leandro A. Oliveira, Luis J. Garay, Luís C. B. Crispino
Using the analogy between acoustic perturbations in an ideal fluid and the description of a Klein-Gordon scalar field in a curved spacetime, we study the quasinormal modes of a qua…
Weyl relativity: A novel approach to Weyl's ideas
Carlos Barceló, Raúl Carballo-Rubio, Luis J. Garay
In this paper we revisit the motivation and construction of a unified theory of gravity and electromagnetism, following Weyl's insights regarding the appealing potential connection…
Gravitational echoes from macroscopic quantum gravity effects
Carlos Barceló, Raúl Carballo-Rubio, Luis J. Garay
New theoretical approaches developed in the last years predict that macroscopic quantum gravity effects in black holes should lead to modifications of the gravitational wave signal…