arXiv subjects

P. Bargueño

Publications and source records attributed to P. Bargueño.

17 recordsLinked to original sources

arXiv2023

A static and spherically symmetric hairy black hole in the framework of the Gravitational Decoupling

In this work we construct a static and spherically symmetric black hole geometry supported by a family of generic mono-parametric sources thorough the Gravitational Decoupling. The parameter characterizing the matter sector can be interpreted as hair which cannot be associated to any global charge. Although the solution is constructed by demanding the weak energy condition, we find that the resulting matter sector satisfies all the energy conditions at and outside the horizon. We study the effect of the hair on the periastron advance and the gravitational lensing of the black hole. We estimate the best WKB order to compute the quasinormal frequencies for scalar, vector and tensor perturbation fields.

gr-qc↗

arXiv2022

Complexity factor for black holes in the framework of the Newman-Penrose formalism

In this work, we introduce the {\it complexity factor} in the context of self--gravitating fluid distributions for the case of black holes by employing the Newman-Penrose formalism. In particular, by working with spherically symmetric and static AdS black holes, we show that the complexity factor can be interpreted in a natural way at the event horizon. Specifically, a thermodynamic interpretation for the aforementioned complexity factor in terms of a pressure partially supporting a Van der Waals-like equation of state is given.

gr-qc↗

arXiv2021

Geodesic analysis and black hole shadows on a general non--extremal rotating black hole in five--dimensional gauged supergravity

In this work, motivated by the fact that higher-dimensional theories predict the existence of black holes which differ from their four-dimensional counterpart, we analyse the geodesics and black hole shadow cast by a general non-extremal five-dimensional black hole. The system under consideration corresponds to the Chong-Cvetič-Lü-Pope (Phys. Rev.Lett.{\bf 95}, 161301 (2005)), which has the Myers--Perry black hole as a limit.

gr-qc↗

arXiv2020

All static spherically symmetric anisotropic solutions for general relativistic polytropes

An algorithm presented by K. Lake to obtain all static spherically symmetric perfect fluid solutions was recently extended by L. Herrera to the interesting case of locally anisotropic fluids (principal stresses unequal). In this work we develop an algorithm to construct all static spherically symmetric anisotropic solutions for general relativistic polytropes. Again the formalism requires the knowledge of only one function (instead of two) to generate all possible solutions. To illustrate the method some known cases are recovered.

gr-qc↗

arXiv2019

Extended gravitational decoupling in $2+1$ dimensional space--times

In this work we extend the so--called Minimal Geometric Deformation method in $2+1$ dimensional space--times with cosmological constant in order to deal with the gravitational decoupling of two circularly symmetric sources. We find that, even though the system here studied is lower dimensional and it includes the cosmological constant, the conditions for gravitational decoupling of two circularly symmetric sources coincides with those found in the $3+1$ dimensional case. We obtain that, under certain circumstances, the extended gravitational decoupling leads to the decoupling of the sources involved in the sense that both the isotropic and the anisotropic sector satisfy Einstein's field equations and the final solution corresponds to a non-linear superposition of two metric components. As particular examples, we implement the method to generate an exterior charged BTZ solution starting from the BTZ vacuum as the isotropic sector and new $2+1$ black hole solutions imposing a barotropic equation of state for the anisotropic sector. We also show that the imposition of a polytropic equation of state of the decoupler matter allows to construct a regular black hole solution in three--dimensional gravity.

gr-qc↗

arXiv2019

Black hole shadow of a rotating polytropic black hole by the Newman--Janis algorithm without complexification

In this work, starting from a spherically symmetric polytropic black hole, a rotating solution is obtained by following the Newman--Janis algorithm without complexification. Besides studying the horizon, the static conditions and causality issues of the rotating solution, we obtain and discuss the shape of its shadow. Some other physical features as the Hawking temperature and emission rate of the rotating polytropic black hole solution are also discussed.

gr-qc↗

arXiv2019

A general interior anisotropic solution for a BTZ vacuum in the context of the Minimal Geometric Deformation decoupling approach

In this work we implement the Minimal Geometric Deformation decoupling method to obtain general static interior solutions for a BTZ vacuum from the most general isotropic solution in $2+1$ dimensions including the cosmological constant $Λ$. We obtain that the general solution can be generated only by the energy density of the original isotropic sector, so that this quantity plays the role of a generating function. Although as a particular example we study the static star with constant density, the method here developed can be easily applied to more complex situations described by other energy density profiles.

gr-qc↗

arXiv2019

Five-dimensional scale-dependent black holes with constant curvature and Solv horizons

In this work, we investigate five-dimensional scale-dependent black hole solutions by modelling their event horizon with some of the eight Thurston three-dimensional geometries. Specifically, we construct constant curvature scale-dependent black holes and also the more exotic scale-dependent Solv black hole. These new solutions are obtained by promoting both the gravitational and the cosmological couplings to $r$-dependent functions, in light of a particular description of the effective action inspired by the high energy philosophy. Interestingly, the so-called running parameter, together with the topology of the event horizon, control the asymptotic structure of the solutions found. Finally, differences in both the entropy and the temperature between the classical and the scale-dependent Solv black hole are briefly commented.

gr-qc↗

arXiv2019

Quasilocal Smarr relations for static black holes

Generalized Smarr relations in terms of quasilocal variables are obtained for Schwarzschild and Reissner-Nordström black holes. The approach is based on gravitational path integrals with finite boundaries on which, following Brown and York, thermodynamic variables are identified through a Hamilton-Jacobi analysis of the action. The resulting expressions allow us to construct the relation between the quasilocal energy obtained in this setting and the Komar and Misner-Sharp energies, which are regarded as thermodynamical internal energy in other approaches. The quasilocal Smarr relation is obtained through scaling arguments, and terms evaluated in the external boundary and the horizon are present. By considering some properties of the metric, it is shown that this quasilocal Smarr relation can be regarded as a thermodynamical realization of Einstein equations. The approach is suitable to be generalized to any spherically symmetric metric.

gr-qc↗

arXiv2018

Scale--dependent Hayward black hole and the generalized uncertainty principle

In this work we present a technique to obtain bounds on the generalized uncertainty principle deformation parameter by using an improved Schwarzschild solution represented by the Hayward metric in the context of scale--dependent gravity. Specifically, this deformation parameter can be interpreted in terms of a running parameter which controls the deviation from the standard Einstein--Hilbert action in the scale--dependent scenario.

gr-qc↗

arXiv2018

SAdS black holes and spacetime atoms: a heuristic approach

In this work, both extended phase space and holographic equipartition approaches are employed to develop an exact Van der Waals description of non--rotating $D=4$ SAdS black holes as an ensemble of spacetime atoms. After a possible microscopical interaction model is introduced, statistical mechanics techniques, with certain heuristic gravitational constraints, are used to derive the equation of state and the Bekenstein--Hawking entropy. The procedure is generalized to the charged $D=4$ SAdS black hole and to arbitrary $D\ge 3$ dimensions for the uncharged cases.

gr-qc↗

arXiv2018

Preliminary test of cosmological models in the scale-dependent scenario

In the present work, we study for the first time a scale--dependent gravitational theory in a cosmological context in a matter--dominated era. In particular, starting from the Einstein Hilbert action with cosmological constant assuming scale--dependent couplings, we derive the corresponding effective Friedmann equations for the model and we solve them. We analyse in detail our results by comparing them with observational $Λ$CDM data as well as the very well-known running vacuum models. Finally, we have provided, in figures, the evolution of the Hubble parameter respect to the redshift as well as the gravitational coupling respect to the Hubble parameter and they show an agreement with the current observations.

gr-qc↗

arXiv2017

Quantum Mechanical Corrections to the Schwarzschild Black Hole Metric

Motivated by quantum mechanical corrections to the Newtonian potential, which can be translated into an $\hbar$-correction to the $g_{00}$ component of the Schwarzschild metric, we construct a quantum mechanically corrected metric assuming $-g_{00}=g^{rr}$. We show how the Bekenstein black hole entropy $S$ receives its logarithmic contribution provided the quantum mechanical corrections to the metric are negative. In this case the standard horizon at the Schwarzschild radius $r_S$ increases by small terms proportional to $\hbar$ and a remnant of the order of Planck mass emerges. We contrast these results with a positive correction to the metric which, apart from a corrected Schwarzschild horizon, leads to a new purely quantum mechanical horizon.

gr-qc↗

arXiv2016

Quantum thermodynamics in chiral two--level systems. The quantum stochastic resonance

A Langevin canonical framework for a chiral two-level system coupled to a bath of harmonic oscillators is used within a coupling scheme different from the well-known spin-boson model. From this stochastic dynamics, within the Markovian regime and Ohmic friction, some standard quantum thermodynamics functions such as the energy average and heat capacity can be extracted. In particular, special emphasis is put on the so-called quantum stochastic resonance which is a cooperative effect of friction, noise and periodic driving occurring in a bistable system.

quant-ph↗

arXiv2013

A Langevin canonical approach to the dynamics of chiral two level systems. Thermal averages and heat capacity

A Langevin canonical framework for a chiral two--level system coupled to a bath of harmonic oscillators is developed within a coupling scheme different to the well known spin-boson model. Thermal equilibrium values are reached at asymptotic times by solving the corresponding set of non--linear coupled equations in a Markovian regime. In particular, phase difference thermal values (or, equivalently, the so--called coherence factor) and heat capacity through energy fluctuations are obtained and discussed in terms of tunneling rates and asymmetries.

cond-mat.stat-mech↗

arXiv2013

On non-dissipative and dissipative qubit manifolds

The trajectories of a qubit dynamics over the two-sphere are shown to be geodesics of certain Riemannian or physically-sound Lorentzian manifolds, both in the non-dissipative and dissipative formalisms, when using action-angle variables. Several aspects of the geometry and topology of these manifolds (qubit manifolds) have been studied for some special physical cases.

math-ph↗

arXiv2012

Two-step condensation of the charged Bose gas

The condensation of the spinless ideal charged Bose gas in the presence of a magnetic field is revisited. The conventional approach is extended to include the macroscopic occupation of excited kinetic states lying in the lowest Landau level, which plays an essential role in the case of large magnetic fields. In that limit, signatures of two diffuse phase transitions (crossovers) appear in the specific heat. In particular, at temperatures lower than the cyclotron frequency, the system behaves as an effectively one-dimensional free boson system, with the specific heat equal to $(1/2)N k_B T$ and a gradual condensation at lower temperatures.

cond-mat.quant-gas↗