18.1k citations
Counting papers with at most 25 authors, so collaboration author lists do not stand in for the people here.
- University of LisbonPT1.3k papers
- Universidade Técnica de LisboaPT388 papers
- Centre National de la Recherche ScientifiqueFR326 papers
- Instituto de Plasmas e Fusão NuclearPT209 papers
- European Organization for Nuclear ResearchCH202 papers
- Centro de Física Teórica de Partículas201 papers
- Instituto Politécnico de LisboaPT190 papers
- Instituto de TelecomunicaçõesPT175 papers
- Universitat de ValènciaES175 papers
- Institut National de Physique Nucléaire et de Physique des ParticulesFR143 papers
- Centro de Astrofísica e GravitaçãoPT133 papers
- LIP - Laboratory of Instrumentation and Experimental Particle PhysicsPT133 papers
25 papers · 2 filters
Noncommutative Black Holes
C. Bastos, O. Bertolami, N. C. Dias +1
One considers phase-space noncommutativity in the context of a Kantowski-Sachs cosmological model to study the interior of a Schwarzschild black hole. It is shown that the potentia…
The vacuum revealed: the final state of vacuum instabilities in compact stars
Paolo Pani, Vitor Cardoso, Emanuele Berti +2
Quantum fields in compact stars can be amplified due to a semiclassical instability. This generic feature of scalar fields coupled to curvature may affect the birth and the equilib…
Superkicks in ultrarelativistic encounters of spinning black holes
Ulrich Sperhake, Emanuele Berti, Vitor Cardoso +2
We study ultrarelativistic encounters of two spinning, equal-mass black holes through simulations in full numerical relativity. Two initial data sequences are studied in detail: on…
Stability of the puncture method with a generalized BSSN formulation
Helvi Witek, David Hilditch, Ulrich Sperhake
The puncture method for dealing with black holes in the numerical simulation of vacuum spacetimes is remarkably successful when combined with the BSSN formulation of the Einstein e…
Entropy of extremal black holes from entropy of quasiblack holes
José P. S. Lemos, Oleg B. Zaslavskii
The entropy of extremal black holes (BHs) is obtained using a continuity argument from extremal quasiblack holes (QBHs). It is shown that there exists a smooth limiting transition…
Head-on collisions of unequal mass black holes in D=5 dimensions
Helvi Witek, Vitor Cardoso, Leonardo Gualtieri +3
We study head-on collisions of unequal mass black hole binaries in D=5 space-time dimensions, with mass ratios between 1:1 and 1:4. Information about gravitational radiation is ext…
Up to eleven: radiation from particles with arbitrary energy falling into higher-dimensional black holes
Emanuele Berti, Vitor Cardoso, Barnabas Kipapa
We consider point particles with arbitrary energy per unit mass E that fall radially into a higher-dimensional, nonrotating, asymptotically flat black hole. We compute the energy a…
Cosmography of f(R) - brane cosmology
Mariam Bouhmadi-Lopez, Salvatore Capozziello, Vincenzo F. Cardone
Cosmography is a useful tool to constrain cosmological models, in particular dark energy models. In the case of modified theories of gravity, where the equations of motion are gene…
Reheating via a generalized non-minimal coupling of curvature to matter
Orfeu Bertolami, Pedro Frazão, Jorge Páramos
In this work one shows that a generalized non-minimal coupling between geometry and matter is compatible with Starobinsky inflation and leads to a successful process of preheating,…
Unparticle inspired corrections to the Gravitational Quantum Well
A. Alves, O. Bertolami
We consider unparticle inspired corrections of the type to the Newtonian potential in the context of the gravitational quantum well. The new energy spectrum…
An Expanding Locally Anisotropic (ELA) Metric Describing Matter in an Expanding Universe
P. Castelo Ferreira
It is suggested an expanding locally anisotropic metric (ELA) ansatz describing matter in a flat expanding universe which interpolates between the Schwarzschild (SC) metric near po…
Using global positioning systems to test extensions of General Relativity
O. Bertolami, J. Páramos
We consider the feasibility of using the Galileo Navigation Satellite System to constrain possible extensions or modifications to General Relativity, by assessing the impact of the…
Numerical relativity for D dimensional space-times: head-on collisions of black holes and gravitational wave extraction
Helvi Witek, Miguel Zilhao, Leonardo Gualtieri +4
Black objects in higher dimensional space-times have a remarkably richer structure than their four dimensional counterparts. They appear in a variety of configurations (e.g. black…
Nonminimal coupling for the gravitational and electromagnetic fields: Traversable electric wormholes
Alexander B. Balakin, José P. S. Lemos, Alexei E. Zayats
We discuss new exact solutions of a three-parameter nonminimal Einstein-Maxwell model. The solutions describe static spherically symmetric objects with and without center, supporte…
Quasiblack holes with pressure: General exact results
José P. S. Lemos, Oleg B. Zaslavskii
A quasiblack hole is an object in which its boundary is situated at a surface called the quasihorizon, defined by its own gravitational radius. We elucidate under which conditions…
Gravitational signature of Schwarzschild black holes in dynamical Chern-Simons gravity
C. Molina, Paolo Pani, Vitor Cardoso +1
Dynamical Chern-Simons gravity is an extension of General Relativity in which the gravitational field is coupled to a scalar field through a parity-violating Chern-Simons term. In…
Quasiblack holes with pressure: relativistic charged spheres as the frozen stars
José P. S. Lemos, Vilson T. Zanchin
In general relativity coupled to Maxwell's electromagnetism and charged matter, when the gravitational potential and the electric potential field obey a relation of the f…
Black holes die hard: can one spin-up a black hole past extremality?
Mariam Bouhmadi-Lopez, Vitor Cardoso, Andrea Nerozzi +1
A possible process to destroy a black hole consists on throwing point particles with sufficiently large angular momentum into the black hole. In the case of Kerr black holes, it wa…
Accelerated expansion from a non-minimal gravitational coupling to matter
O. Bertolami, P. Frazao, J. Páramos
It is shown that a non-minimal coupling between the scalar curvature and the matter Lagrangian density may account for the accelerated expansion of the Universe and provide, throug…
Ultra-relativistic grazing collisions of black holes
U. Sperhake, V. Cardoso, F. Pretorius +3
We study gravitational wave emission, zoom-whirl behavior and the resulting spin of the remnant black hole in highly boosted collisions of equal-mass, non spinning black-hole binar…
Semianalytical estimates of scattering thresholds and gravitational radiation in ultrarelativistic black hole encounters
Emanuele Berti, Vitor Cardoso, Tanja Hinderer +4
Ultrarelativistic collisions of black holes are ideal gedanken experiments to study the nonlinearities of general relativity. In this paper we use semianalytical tools to better un…
Noncommutative effects in astrophysical objects: a survey
Orfeu Bertolami, Carlos A. D. Zarro
The main implications of noncommutativity over astrophysical objects are examined. Noncommutativity is introduced through a deformed dispersion relation $E^{2}=p^{2}c^{2}(1+λE)^{2}…
Probing spacetime fluctuations using cold atom traps
Charles H. -T. Wang, Robert Bingham, J. Tito Mendonca
We investigate the position oscillation of a particle that models the center of mass quantum state of a trapped Bose-Einstein condensate coupled to the zero-point fluctuations of t…
Gravitational-wave signatures of the absence of an event horizon. II. Extreme mass ratio inspirals in the spacetime of a thin-shell gravastar
Paolo Pani, Emanuele Berti, Vitor Cardoso +2
We study gravitational-wave emission from the quasi-circular, extreme mass ratio inspiral of compact objects of mass m0 into massive objects of mass M>>m0 whose external metric is…