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
22 papers · 2 filters
On the instability of Reissner-Nordstrom black holes in de Sitter backgrounds
Vitor Cardoso, Madalena Lemos, Miguel Marques
Recent numerical investigations have uncovered a surprising result: Reissner-Nordstrom-de Sitter black holes are unstable for spacetime dimensions larger than 6. Here we prove the…
Comment on "Kerr Black Holes as Particle Accelerators to Arbitrarily High Energy"
Emanuele Berti, Vitor Cardoso, Leonardo Gualtieri +2
It has been suggested that rotating black holes could serve as particle colliders with arbitrarily high center-of-mass energy. Astrophysical limitations on the maximal spin, back-r…
Appeasing the Phantom Menace?
Mariam Bouhmadi-Lopez, Yaser Tavakoli, Paulo Vargas Moniz
An induced gravity brane-world model is considered herein. A Gauss-Bonnet term is provided for the bulk, whereas phantom matter is present on the brane. It is shown that a combinat…
Modified theories of gravity with non-minimal curvature-matter coupling
Orfeu Bertolami, Miguel Carvalho Sequeira
In this contribution one examines the generalization of the theories of gravity where one introduces a non-minimal coupling between curvature and matter. This model has new…
Stability of mass varying particle lumps
Alex E. Bernardini, O. Bertolami
The theoretical description of compact structures that share some key features with mass varying particles allows for a simple analysis of equilibrium and stability for massive ste…
Thermodynamic equilibrium conditions for mass varying particle structures
Alex E. Bernardini, O. Bertolami
The thermodynamic equilibrium conditions for compact structures composed by mass varying particles are discussed assuming that the so-called dynamical mass behaves like an addition…
Gravitational wave signatures of the absence of an event horizon. I. Nonradial oscillations of a thin-shell gravastar
Paolo Pani, Emanuele Berti, Vitor Cardoso +2
Gravitational waves from compact objects provide information about their structure, probing deep into strong-gravity regions. Here we illustrate how the presence or absence of an e…
Perturbations of Schwarzschild black holes in Dynamical Chern-Simons modified gravity
V. Cardoso, L. Gualtieri
Dynamical Chern-Simons (DCS) modified gravity is an attractive, yet relatively unexplored, candidate to an alternative theory of gravity. The DCS correction couples a dynamical sca…
Towards a Noncommutative Astrophysics
Orfeu Bertolami, Carlos A. D. Zarro
We consider astrophysical objects such as main-sequence stars, white-dwarfs and neutron stars in a noncommutative context. Noncommutativity is implemented via a deformed dispersion…
Black Holes and Phase Space Noncommutativity
C. Bastos, O. Bertolami, N. C. Dias +1
We use the solutions of the noncommutative Wheeler-De Witt equation arising from a Kantowski-Sachs cosmological model to compute thermodynamic properties of the Schwarzschild black…
Cross section, final spin and zoom-whirl behavior in high-energy black hole collisions
U. Sperhake, V. Cardoso, F. Pretorius +3
We study the collision of two highly boosted equal mass, nonrotating black holes with generic impact parameter. We find such systems to exhibit zoom-whirl behavior when fine tuning…
On the quantum fate of singularities in a dark-energy dominated universe
Mariam Bouhmadi-Lopez, Claus Kiefer, Barbara Sandhoefer +1
Classical models for dark energy can exhibit a variety of singularities, many of which occur for scale factors much bigger than the Planck length. We address here the issue whether…
Formation of Higher-dimensional Topological Black Holes
Filipe C. Mena, Jose Natario, Paul Tod
We study higher dimensional gravitational collapse to topological black holes in two steps. Firstly, we construct some (n+2)-dimensional collapsing space-times, which include gener…
Electrically charged fluids with pressure in Newtonian gravitation and general relativity in d spacetime dimensions: theorems and results for Weyl type systems
José P. S. Lemos, Vilson T. Zanchin
Previous theorems concerning Weyl type systems, including Majumdar-Papapetrou systems, are generalized in two ways, namely, we take these theorems into d spacetime dimensions (${\r…
The cosmological constant problem: a user's guide
Orfeu Bertolami
We discuss the validity of general relativity at low-energy and relate the threshold below which the theory breaks down with the observed value of the cosmological constant. This s…
Quasinormal modes of black holes and black branes
Emanuele Berti, Vitor Cardoso, Andrei O. Starinets
Quasinormal modes are eigenmodes of dissipative systems. Perturbations of classical gravitational backgrounds involving black holes or branes naturally lead to quasinormal modes. T…
Parametric instability induced scalar gravitational waves from a model pulsating neutron star
Charles H. -T. Wang, Paolo M. Bonifacio, Robert Bingham +1
We identify a new dynamical mechanism for a strong scalar gravitational field effect. To illustrate this mechanism, we investigate the parametric excitation and emission of scalar…
Entropy of quasiblack holes
José P. S. Lemos, Oleg B. Zaslavskii
We trace the origin of the black hole entropy S replacing a black hole by a quasiblack hole. Let the boundary of a static body approach its own gravitational radius, in such a way…
A Quantum Goldman Bracket for Loops on Surfaces
J. E. Nelson, R. F. Picken
In the context of (2+1)--dimensional gravity, we use holonomies of constant connections which generate a --deformed representation of the fundamental group to derive signed area…
Energy Conditions and Stability in theories of gravity with non-minimal coupling to matter
Orfeu Bertolami, Miguel Carvalho Sequeira
Recently, in the context of modified theories of gravity, a new type of model has been proposed where one directly couples the scalar curvature to matter. As any model in $f…
The angular momentum and mass formulas for rotating stationary quasi-black holes
José P. S. Lemos, Oleg B. Zaslavskii
We consider the quasi-black hole limit of a stationary body when its boundary approaches its own gravitational radius, i.e., its quasi-horizon. It is shown that there exists a perf…
Hamiltonian thermodynamics of d-dimensional (d=4 and d>4) Reissner-Nordström anti-de Sitter black holes with spherical, planar, and hyperbolic topology
Gonçalo A. S. Dias, José P. S. Lemos
The Hamiltonian thermodynamics formalism is applied to the general -dimensional Reissner-Nordström-anti-de Sitter black hole with spherical, planar, and hyperbolic horizon topol…