results for au:Larranaga_A in:gr-qc

- Oct 17 2014 gr-qc arXiv:1410.4190v3In this paper we calculate the strong field limit deflection angle for a light ray passing near a scalar charged spherically symmetric object, described by a metric which comes from the low-energy limit of heterotic string theory. Then, we compare the expansion parameters of our results with those obtained in the Einstein's canonical frame, obtained by a conformal transformation, and we show that, at least at first order, the results do not agree.
- This article has been withdrawn by arXiv admins due to excessive reuse of content from other authors. We also note that this article has been retracted from Physics Letters B at http://doi.org/10.1016/j.physletb.2015.03.024
- Oct 10 2012 gr-qc arXiv:1210.2650v1We calculate the Komar energy $E$ for a charged black hole inspired by noncommutative geometry and identify the total mass ($M_{0}$) by considering the asymptotic limit. We also found the generalized Smarr formula, which shows a deformation from the well known relation $M_{0}-\frac{Q_{0}^{2}}{r}=2ST$ depending on the noncommutative scale length $\ell$ .
- Apr 18 2012 gr-qc arXiv:1204.3696v1The thermodynamics of the Kerr-AdS black hole is reformulated within the context of the formalism of geometrothermodynamics (GTD) and the cosmological constant is considered as a new thermodynamical parameter. We conclude that the mass of the black hole corresponds to the total enthalpy of this system. Choosing appropriately the metric in the equilibrium states manifold, we study the phase transitions as a divergence of the thermodynamical curvature scalar. This approach reproduces the Hawking-Page transition and shows that considering the cosmological constant as a thermodynamical parameter does not contribute with new phase transitions.
- Using adiabatic invariance and the Bohr-Sommerfeld quantization rule we investigate the entropy spectroscopy of a charged black hole of heterotic string theory. It is shown that the entropy spectrum is equally spaced identically to the Schwarzschild, Reissner-NordstrÃ¶m and Kerr black holes. Since the adiabatic invariance method does not use quasinormal mode analysis, there is no need to impose the small charge limit and no confusion on whether the real part or imaginary part is responsible for the entropy spectrum.
- The recent proposal of Maggiore that the periodicity of a black hole may be the origin of area quantization law is analyzed in the context of three dimensional black holes. We use the period of motion of an outgoing wave which is shown to be related to the vibrational frequency of the perturbed black hole, to quantize the horizon area of rotating and non-rotating BTZ black holes. It is shown that the equally spaced area spectrum takes the same form as the obtained in the literature using the quasinormal mode analysis for both metrics. Using this method, we do not need to use the small angular momentum assumption which is necessary in the quasinormal mode approach for the rotating black hole.
- The recent proposal of Maggiore that the periodicity of a black hole may be the origin of area quantization law is analyzed in the context of black holes in string theory. We use the period of motion of an outgoing wave, which is shown to be related to the vibrational frequency of the perturbed black hole, to quantize the horizon areas of a Sen black hole. It is shown that the equally spaced area spectrum takes the same form as the obtained by Zeng et. al. for Schwarzschild and Kerr black holes and the spacing is the same as that obtained through the quasinormal mode frequencies. In order to obtain this result, we do not need to use the small angular momentum assumption which is necessary in the quasinormal mode approach.
- Feb 23 2012 gr-qc arXiv:1202.4951v1We present an elementary derivation of the planetary advance of the perihelion for a general spherically symmetric line element in the post- newtonian approximation.
- Oct 05 2011 gr-qc arXiv:1110.0778v1By considering particles as smeared objects, we investigate the effects of space noncommutativity on the geodesic structure in Schwarzschild-AdS spacetime. By means of a detailed analysis of the corresponding effective potentials for particles, we find the possible motions which are allowed by the energy levels. Radial and non-radial trajectories are treated and the effects of space noncommutativity on the value of the precession of the perihelion are estimated. We show that the geodesic structure of this black hole presents new types of motion not allowed by the Schwarzschild spacetime.
- In the context of f(R) theories of gravity, we address the problem of finding a rotating charged black hole solution in the case of constant curvature. The new metric is obtained by solving the field equations and we show that the behavior of it is typical of a rotating charged source. In addition, we analyze the thermodynamics of the new black hole. The results ensures that the thermodynamical properties in f(R) gravities are qualitatively similar to those of standard General Relativity.
- The thermodynamics of the Schwarzschild-AdS black hole is reformulated within the context of the recently developed formalism of geometrothermodynamics (GTD). Different choices of the metric in the equilibrium states manifold are used in order to reproduce the Hawking-Page phase transition as a divergence of the thermodynamical curvature scalar. We show that the enthalpy and total energy representations of GTD does not reproduce the transition while the entropy rep- resentation gives the expected behavior.
- The thermodynamics of the Gibbons-Maeda-Garfinkle-Horowitz-Strominger (GMGHS) charged black hole from string theory is reformulated within the context of the recently developed formalism of geometrothermodynamics. The geometry of the space of equilibrium states is curved, but we show that the thermodynamic curvature does not diverge when the black hole solution becomes a naked singularity. This provides a counterexample to the conventional notion that a thermodynamical curvature divergence signals the occurrence of a phase transition.
- We find a new charged black hole in three-dimensional anti-de Sitter space using an anisotropic perfect fluid inspired by the noncommutative black hole as the source of matter and a gaussian distribution of electric charge. We deduce the thermodynamical quantities of this black hole and compare them with those of a charged BTZ solution.
- We find a new rotating black hole in three-dimensional anti-de Sitter space using an anisotropic perfect fluid inspired by the noncommutative black hole. We deduce the thermodynamical quantities of this black hole and compare them with those of a rotating BTZ solution.
- We study the entropy of Kerr-Sen black hole of heterotic string theory beyond semiclassical approximations. Applying the properties of exact differentials for three variables to the first law thermodynamics we derive the corrections to the entropy of the black hole. The leading (logarithmic) and non leading corrections to the area law are obtained.
- We study the entropy of the Gibbons-Maeda-Garfinkle-Horowitz-Strominger (GMGHS) charged black hole, originated from the effective action that emerges in the low-energy of string theory, beyond semiclassical approximations. Applying the properties of exact differentials for three variables to the first law thermodynamics we derive the quantum corrections to the entropy of the black hole. The leading (logarithmic) and non leading corrections to the area law are obtained.
- Feb 19 2010 gr-qc arXiv:1002.3416v2Using the AdS/CFT correspondence we calculate the explicit form of the entanglement entropy for the charged BTZ black hole. The leading term in the large temperature expansion of the entropy function for this black hole reproduces its Bekenstein-Hawking entropy and the subleading term, representing the first corrections due to quantum entanglement, behaves as a logarithm of the BH entropy.
- Jun 26 2009 gr-qc arXiv:0906.4580v1In a recent propposal, the cosmological constant has been considered as as a new thermodynamical variable and its change is related to the radiation produced by black holes. Using this consideration and by modelling the primordial black holes as Schwarzschild-de Sitter holes,we have constrained the total mass of primordial black holes evaporated by now, giving an estimate of the order of 1.624x10^24 solar masses.
- Jun 25 2009 gr-qc arXiv:0906.4380v2We study the entropy of black holes in the deformed Horava-Lifshitz gravity with coupling constant lambda. For lambda=1, the black hole resembles the Reissner-Norstrom black hole with a geometric parameter acting like the electric charge. Therefore, we obtain some differences in the entropy when comparing with the Schwarzschild black hole. Finally, we study the heat capacity and the thermodynamical stability of this solution.
- Jan 26 2009 gr-qc arXiv:0901.3727v1In this paper, we study the thermodynamical properties of the (2+1) dimensional black hole with a non-linear electrodynamics and with a negative cosmological constant, using the Generalized Uncertainty Principle (GUP). This approach shows that there is a minimum mass or remnant for the black hole, corresponding to the minimum radius of the event horizon that has a size of the order of the Planck scale. We also show that the heat capacity for this black hole is always positive.
- Dec 23 2008 gr-qc arXiv:0812.4180v2In this paper, we study the thermodynamical properties of the (2+1)dimensional black hole with a non-linear electrodynamics and without cosmological constant using the Generalized Uncertainty Principle (GUP). This approach shows that there is a maximum temperature for the black hole depending only on the electric charge and corresponding to the minimum radius of the event horizon, of the order of the Planck scale. Finally we show that the heat capacity for this black hole has the expected behavior.
- Nov 21 2008 gr-qc arXiv:0811.3368v2In this paper, we study the thermodynamical properties of the (2+1)dimensional black hole with a Coulomb-like electric field and the differential form of the first law of thermodynamics is derived considering a virtual displacement of its event horizon. This approach shows that it is possible to give a thermodynamical interpretation to the field equations near the horizon. The Lambda=0 solution is studied and its interesting thermodynamical properties are commented.
- On the Thermodynamical Relation between Rotating Charged BTZ Black Holes and Effective String TheoryMar 14 2008 gr-qc arXiv:0803.1998v1In this paper we study the first law of thermodynamics for the (2+1) dimensional rotating charged BTZ black hole considering a pair of thermodinamical systems constructed with the two horizons of this solution. We show that these two systems are similar to the right and left movers of string theory and that the temperature associated with the black hole is the harmonic mean of the temperatures associated with these two systems.
- Nov 01 2007 gr-qc arXiv:0711.0012v1In this paper we will show that using the cosmological constant as a new thermodynamical state variable, the differential and integral mass formulas of the first law of thermodynamics for asymptotic flat spacetimes can be extended to be used at the two horizons of the (2+1) dimensional BTZ black hole. We also extend this equations to the stringy description of the BTZ black hole, in which two new systems that resemble the right and left modes of effective string theory, are defined in terms of the inner and outer horizons.
- In this paper we study the first law of thermodynamics for the (2+1) dimensional charged BTZ black hole considering a pair of thermodinamical systems constructed with the two horizons of this solution. We show that these two systems are similar to the right and left movers of string theory and that the temperature associated with the black hole is the harmonic mean of the temperatures associated with these two systems.
- Sep 27 2007 gr-qc arXiv:0709.4257v2In this paper we study the first law of thermodynamics for the (2+1) dimensional BTZ rotating black hole considering a pair of thermodinamical systems constructed with the two horizons of this solution. We show that these two systems are similar to the right and left movers of string theory and that the temperature associated with the black hole is the harmonic mean of the temperatures associated with these two systems.
- Jul 17 2007 gr-qc arXiv:0707.2256v1In this paper we will show that using the cosmological constant as a new thermodynamical state variable, the differential and integral mass formulas of the first law of thermodynamics for asymptotic flat spacetimes can be extended to (2+1) dimensional charged BTZ black holes and charged de Sitter space.
- Jul 09 2007 gr-qc arXiv:0707.0900v2Wormholes have been always an interesting object in gravity theories. In this paper we make a little review of the principal properties of these objects and the exotic matter they need to exist. Then, we obtain two specific solutions in the formalism of (2+1)-dimensional gravity with negative cosmological constant. The obtained geometries correspond to traversable wormholes with an exterior geometry correspondient to the well known BTZ black hole solution. We also discuss the distribution of exotic matter that these wormholes need.
- Jun 13 2007 gr-qc arXiv:0706.1599v3As is already known, a spacetime horizon acts like a boundary of a thermal system an we can associate with it notions as temperature and entropy. Following the work of M. Akbar, in this paper we will show how it is possible to interpret the field equation of a charged BTZ black hole near horizon as a thermodynamic identity dE=TdS+PdA+PhidQ, where Phi is the electric potential and Q is the electric charge of BTZ black hole. These results indicate that the field equations for the charged BTZ black hole possess intrinsic thermodynamic properties near horizon.
- Jun 12 2007 gr-qc arXiv:0706.1271v2Traversable wormholes are objects that present a lot of interest in the last years because of their geometric features and their relation with exotic matter. In this paper we presnt a review of the principal characteristics of traversable Morris-Thorne wormholes, their construction proccess and some aspects about the exotic matter that is needed in order to mantain them. Then, we use a junction proccess to obatin two specific wormhole solutions in the (2+1) gravity formalism with negative cosmological constant. The obtained solutions represent wormholes with an external spacetime correspondient to the BTZ black hole solution. We also show that exotic matter is needed to mantain these wormholes. ----- Los agujeros de gusano atravesables son objetos que presentan un gran interes en la actualidad debido a sus caracteristicas geometricas y a su relacion con la materia exotica. En el presente trabajo se muestra una revision de las caracteristicas de los agujeros de gusano atravesables al estilo de Morris y Thorne, al igual que el proceso de construccion y aspectos de la materia exotica necesaria para mantenerlos. Luego, se utiliza un proceso de juntura para construir dos soluciones especificas tipo agujero de gusano en el formalismo de la gravedad (2+1) con constante cosmologica negativa. Con esta construccion, se obtienen agujeros atravesables que se encuentran unidos a un espacio-tiempo externo correspondiente al agujero negro BTZ sin momento angular y sin carga electrica. Ademas de esto, se muestra que para mantener este tipo de solucion es necesaria la existencia de materia exotica, es decir, materia que viole las condiciones de energia.
- May 13 2005 gr-qc arXiv:gr-qc/0505054v6Natural wormholes and its astrophysical signatures have been sugested in various oportunities. By applying the strong field limit of gravitational lensing theory, we calculate the deflection angle and magnification curves produced by Morris-Thorne wormholes in asimptotically flat space-times. The results show that wormholes act like convergent lenses. Therefore, we show that it is hard to distinguish them from black holes using the deflection's angle of the gravitational lens effect, in contrast with the results reported by Cramer et.al. and Safanova et.al. However, we also show that it is possible, in principle, distinguish them by the magnification curves, in particular, by observing the position of the peak of the Einstein's ring.
- Sep 24 2003 gr-qc arXiv:gr-qc/0309108v3We calculate the time delay between different relativistic images formed by the gravitational lensing produced by the Gibbons-Maeda-Garfinkle-Horowitz-Stromiger (GMGHS) charged black hole of heterotic string theory. Modeling the supermassive central objects of some galaxies as GMGHS black holes, numerical values of the time delays are estimated and compared with the correspondient Reissner-Nordstrom black holes . The time difference amounts to hours, thus being measurable and permiting to distinguish between General Relativity and String Theory charged black holes.
- Jun 17 2003 gr-qc arXiv:gr-qc/0306060v2Introductory Notes in Bosonic String Theory and its Canonical Quantization.
- Jun 10 2003 gr-qc arXiv:gr-qc/0306033v2These Lecture notes give an introduction to Regge calculus as a discrete model of General Relativity.