Yerko Vasquez

Exact charged black-hole solutions in D-dimensional f (T) gravity: torsion vs curvature analysis

A bstractWe extract exact charged black-hole solutions with flat transverse sections in the framework of D-dimensional Maxwell-f (T) gravity, and we analyze the singularities and horizons based on both torsion and curvature invariants. Interestingly enough, we find that in some particular solution subclasses there appear more singularities in the curvature scalars than in the torsion ones. This difference disappears in the uncharged case, or in the case where f (T) gravity becomes the usual linear-in-T teleparallel gravity, that is General Relativity. Curvature and torsion invariants behave very differently when matter fields are present, and thus f (R) gravity and f (T) gravity exhibit different features and cannot be directly re-casted each other.

Circularly symmetric solutions in three-dimensional teleparallel, f (T ) and Maxwell-f (T ) gravity

A bstractWe present teleparallel 3D gravity and we extract circularly symmetric solutions, showing that they coincide with the BTZ and Deser-de-Sitter solutions of standard 3D gravity. However, extending into f (T ) 3D gravity, that is considering arbitrary functions of the torsion scalar in the action, we obtain BTZ-like and Deser-de-Sitter-like solutions, corresponding to an effective cosmological constant, without any requirement of the sign of the initial cosmological constant. Finally, extending our analysis incorporating the electromagnetic sector, we show that Maxwell-f (T ) gravity accepts deformed charged BTZ-like solutions. Interestingly enough, the deformation in this case brings qualitatively novel terms, contrary to the pure gravitational solutions where the deformation is expressed only through changes in the coefficients. We investigate the singularities and the horizons of the new solutions, and amongst others we show that the cosmic censorship can be violated. Such novel behaviors reveal the new features that the f (T ) structure brings in 3D gravity.

Quasinormal modes and Stability Analysis for 4-dimensional Lifshitz Black Hole

We study the Lifshitz black hole in four dimensions with dynamical exponent z = 2 and we calculate analytically the quasinormal modes of scalar perturbations. These quasinormal modes allow to study the stability of the Lifshitz black hole and we have obtained that Lifshitz black hole is stable.

Quasinormal modes, stability analysis and absorption cross section for 4-dimensional topological Lifshitz black hole

We study scalar perturbations in the background of a topological Lifshitz black hole in four dimensions. We compute analytically the quasinormal modes and from these modes we show that topological Lifshitz black hole is stable. On the other hand, we compute the reflection and transmission coefficients and the absorption cross section and we show that there is a range of modes with high angular momentum which contributes to the absorption cross section in the low frequency limit. Furthermore, in this limit, we show that the absorption cross section decreases if the scalar field mass increases, for a real scalar field mass.

Particles motion on topological Lifshitz black holes in 3+1 dimensions

In the present paper we study the causal structure of a topological black hole presented by Mann R.B. (in J. High Energy Phys. 06:075, 2009) by mean the standard Lagrangian procedure, which allow us analyze qualitatively the behavior of test particles using the effective potential. Then, the geodesic motion of massive and massless particles is obtained analytically. We find that confined orbits are forbidden on this spacetime, however radial photons can escape to infinity in an infinite proper time but in a finite coordinate time, this correspond to an interesting and novel result.

Scalar field scattering by a Lifshitz black hole under a non-minimal coupling

We study the behavior of a scalar field under a z = 3 Lifshitz black hole background, in a way that is non-minimally coupled to the gravitational field . A general analytical solution is obtained along with two sets of quasinormal modes associated to different boundary conditions that can be imposed on the scalar field, non-minimal coupling parameter appears explicitly on these solutions. Stability of quasinormal modes can be studied and ensured for both cases. Also, the reflection and absorption coe ffi cients are calculated, as well as the absorption cross secti on which features an interesting behavior because of being attenuated by terms strongly dependant on the non-minimal coupling. By a suitable change of variables a soliton solution can also be obtained and the stability of the quasinormal modes are studied and ensured.

Teleparallel Equivalent of Lovelock Gravity

There is a growing interest in modified gravity theories based on torsion, as these theories exhibit interesting cosmological implications. In this work, inspired by the teleparallel formulation of general relativity, we present its extension to Lovelock gravity known as the most natural extension of general relativity in higher-dimensional space-times. First, we review the teleparallel equivalent of general relativity and Gauss-Bonnet gravity, and then we construct the teleparallel equivalent of Lovelock gravity. In order to achieve this goal we use the vielbein and the connection without

QUASINORMAL MODES AND STABILITY ANALYSIS FOR Z = 4 TOPOLOGICAL BLACK HOLE IN 4 + 1-DIMENSIONAL HORAVA–LIFSHITZ GRAVITY

We study the stability of z = 4 topological black hole in 4 + 1-dimensional Horava–Lifshitz gravity against scalar perturbations by analyzing the quasinormal modes (QNMs). It is possible to distinguish two cases for which the black hole is stable. The first one occurs when p + Q > 0 and QNMs are characterized by a real and imaginary part, meaning that the field has oscillatory modes but with Im(ω) < 0; therefore, it is stable. While in the second case p + Q < 0, QNMs are purely imaginary (Im(ω) < 0) and then absolutely damped.

Minimal Log Gravity

Fil: Giribet, Gaston Enrique. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Instituto de Fisica de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisica de Buenos Aires; Argentina. Pontificia Universidad Catolica de Valparaiso; Chile

Scalar field perturbations of a Lifshitz black hole in conformal gravity in three dimensions

We study the reflection and transmission coefficients and the absorption cross section for scalar fields in the background of a Lifshitz black hole in three-dimensional conformal gravity with