arXiv subjects

Angel Rincon

Publications and source records attributed to Angel Rincon.

At least 55 records · Page 3Linked to original sources

arXiv2020

Beyond classical anisotropy and a new look to relativistic stars: a gravitational decoupling approach

In this article, we propose a physical condition to extend interior isotropic solutions to anisotropic domains by gravitational decoupling in the framework of the Minimal Geometric Deformation approach. In particular, it is found that by using an expression reminiscent of the classical anisotropy factor, we can close the decoupling system of equations and a new anisotropic solution can be found. As an example, we extend the well--known Tolman IV.

gr-qc↗

arXiv2020

Dynamical systems methods and statefinder diagnostic of interacting vacuum energy models

We study three interacting dark energy models within the framework of four-dimensional General Relativity and a spatially flat Universe. In particular, we first consider two vacuum models where dark energy interacts with dark matter, while relativistic matter as well as baryons are treated as non-interacting fluid components. Secondly, we investigate a third model where the gravitational coupling is assumed to be a slowly-varying function of the Hubble rate and dark energy and dark matter interact as well. We compute the statefinders parameters versus red-shift as well as the critical points and their nature applying dynamical systems methods. In the case of only an interaction term, our main findings indicate that i) significant differences between the models are observed as we increase the strength of the interaction term, and ii) all the models present an unique attractor corresponding to acceleration. On the other hand, when we allow for a variable gravitational coupling, we find that i) the deviation from the concordance model depends of both the strength of gravitational coupling parameter and the interaction term, and ii) there is an unique attractor corresponding to acceleration.

gr-qc↗

arXiv2020

Scale-dependent rotating BTZ black hole

This work presents a generalization of the rotating black hole in two plus one dimensions, in the light of scale--dependent gravitational couplings. In particular, the gravitational coupling $κ_0$ and the cosmological term $Λ_0$ are not forced to be constants anymore. Instead, $κ$ and $Λ$ are allowed to change along the radial scale $r$. The effective Einstein field equations of this problem are solved by assuming static rotational symmetry and by maintaining the usual structure of the line element. For this generalized solution, the asymptotic behavior, the horizon structure, and the thermodynamic properties are analyzed.

hep-th↗

arXiv2019

Cosmological constant problem: deflation during inflation

We argue that the discrepancy between the Planck mass scale and the observed value of the cosmological constant can be largely attenuated if those quantities are understood as a result of effective, and thus scale-dependent, couplings. We exemplify this mechanism for the early inflationary epoch of the universe by solving the corresponding effective gap equations, subject to an energy condition. Several non-trivial checks and extensions are discussed. A comparison of our results to the renormalization group flow, obtained within the asymptotic safety program reveals a stunning agreement.

gr-qc↗

arXiv2019

Minimal Geometric Deformation in a Reissner-Nordström background

This article is devoted to the study of new exact analytical solutions in the background of Reissner-Nordström space-time by using gravitational decoupling via minimal geometric deformation approach. To do so, we impose the most general equation of state, relating the components of the $θ$-sector in order to obtain the new material contributions and the decoupler function $f(r)$. Besides, we obtain the bounds on the free parameters of the extended solution to avoid new singularities. Furthermore, we show the finitude of all thermodynamic parameters of the solution such as the effective density $\tildeρ$, radial $\tilde{p}_{r}$ and tangential $\tilde{p}_{t}$ pressure for different values of parameter $α$ and the total electric charge $Q$. Finally, the behavior of some scalar invariants, namely the Ricci $R$ and Kretshmann $R_{μνωε}R^{μνωε}$ scalars are analyzed. It is also remarkable that, after an appropriate limit, the deformed Schwarzschild black hole solution always can be recovered.

gr-qc↗

arXiv2019

Model comparison using supernovae and Hubble parameter data

We compare several well-known cosmological dark energy models using observational data coming both from type Ia supernovae and from Hubble parameter measurements. First we use supernovae data to determine the free parameters of each model except for the Hubble constant $H_0$. Then, we use the Hubble parameter measurements to determine $H_0$, and finally the age of the Universe for each model is computed. Our main numerical results are summarized in tables, and they are briefly discussed. The prediction for the decelerating parameter as a function of red-shift for each model is shown in the same figure for comparison. Our numerical results seem to indicate a correlation between the deceleration parameter and the value of the Hubble constant.

gr-qc↗

arXiv2018

Charged slowly rotating toroidal black holes in the (1+3)-dimensional Einstein-power-Maxwell theory

In this work we find charged slowly rotating solutions in the four-dimensional Einstein-power-Maxwell non-linear electrodynamics assuming a negative cosmological constant. By solving the system of coupled field equations explicitly we obtain an approximate analytical solution in the small rotation limit. The solution obtained is characterized by a flat horizon structure, and it corresponds to a toroidal black hole. The Smarr's formula, the thermodynamics and the invariants Ricci scalar and Kretschmann scalar are briefly discussed.

gr-qc↗

arXiv2018

Scale-dependent (2+1) - dimensional electrically charged black holes in Einstein-power-Maxwell theory

In this work we extend and generalize our previous work on the scale dependence at the level of the effective action of black holes in the presence of non-linear electrodynamics. In particular, we consider the Einstein-power-Maxwell theory without a cosmological constant in (2+1) dimensions, assuming a scale dependence of both the gravitational and the electromagnetic coupling and we investigate in detail how the scale--dependent scenario affects the horizon and thermodynamic properties of the classical black holes for any value of the power parameter. In addition, we solve the corresponding effective field equations imposing the "null energy condition" in order to obtain analytical solutions. The implications of quantum corrections are also briefly discussed.

hep-th↗

arXiv2018

Greybody factors for a minimally coupled scalar field in three-dimensional Einstein-power-Maxwell black hole background

In the present work we study the propagation of a probe minimally coupled scalar field in Einstein-power-Maxwell charged black hole background in (1+2) dimensions. We find analytical expressions for the reflection coefficient as well as for the absorption cross-section in the low energy regime, and we show graphically their behaviour as functions of the frequency for several values of the free parameters of the theory.

hep-th↗

arXiv2018

Scale-dependent polytropic black hole

In the present work we study the scale--dependence of polytropic non-charged black holes in (3+1)-dimensional space--times assuming a cosmological constant. We allow for scale--dependence of the gravitational and cosmological couplings, and we solve the corresponding generalized field equations imposing the null energy condition. Besides, some properties, such as horizon structure and thermodynamics, are discussed in detail.

gr-qc↗

arXiv2018

Quasinormal modes of scale dependent black holes in (1+2)-dimensional Einstein-power-Maxwell theory

We study for the first time the stability against scalar perturbations, and we compute the spectrum of quasinormal modes of three-dimensional charged black holes in Einstein-power-Maxwell non-linear electrodynamics assuming running couplings. Adopting the 6th order WKB approximation we investigate how the running of the couplings change the spectrum of the classical theory. Our results show that all modes corresponding to non-vanishing angular momentum are unstable both in the classical theory and with the running of the couplings, while the fundamental mode can be stable or unstable depending on the running parameter and the electric charge.

hep-th↗

arXiv2018

Stability of cosmic structures in scalar-tensor theories of gravity

In the present work we study a concrete model of Scalar--Tensor theory of gravity characterized by two free parameters, and compare its predictions against observational data and constraints coming from supernovae, solar system tests as well as the stability of cosmic structures. First an exact analytical solution at the background level is obtained. Then using that solution the expression for the turnaround radius is computed. Finally we show graphically how current data and limits put bounds on the parameters of the model at hand.

astro-ph.CO↗

arXiv2017

A regular scale-dependent black hole solution

In this work, we present a regular black hole solution, in the context of scale-dependent General Relativity, satisfying the weak energy condition. The source of this solution is an anisotropic effective energy-momentum tensor which appears when the scale dependence of the theory is turned-on. In this sense, the solution can be considered as a semiclassical extension of the Schwarzschild one.

gr-qc↗

arXiv2017

Quasinormal modes of black holes in Einstein-power-Maxwell theory

In the present work we compute the spectrum of quasinormal frequencies of four-dimensional charged black holes in Einstein-power-Maxwell theory. In particular we study scalar perturbations adopting the 6th order WKB approximation. We analyze in detail the behaviour of the spectrum depending on the charge of the black hole, the quantum number of angular momentum and the overtone number. In addition, a comparison is made between the results obtained here and the results valid for charged black holes in other theories as well as for the Reissner-Nordstr${ö}$m black hole. Finally, we have provided an analytical expression for the quasinormal spectrum in the eikonal limit.

hep-th↗

arXiv2017

Greybody factors for a nonminimally coupled scalar field in BTZ black hole background

In the present work we study the propagation of a probe nonminimally coupled scalar field in BTZ black hole background. We find analytical expressions for the reflection coefficient, the absorption cross-section, and the decay rate in the strong coupling case, where the nonminimal coupling is larger than its conformal value $ξ_{c}= 1/6$. Our main results are summarized in several figures, in which we show how the behavior of the aforementioned quantities depends on the parameters of the theory. Our findings show that i) the reflection coefficient tends to zero only for a nonminimal coupling $ξ\geq 0.25$, and ii) in the zero angular-momentum case the greybody factor in the low energy regime tends to a finite constant that generically does not coincide with the area of the horizon of the black hole. There is, however, a special case in which this holds.

hep-th↗

arXiv2017

Greybody factors for a minimally coupled massless scalar field in Einstein-Born-Infeld dilaton spacetime

We have analyzed in detail the propagation of a minimally coupled massless scalar field in the gravitational background of a four-dimensional Einstein-Born-Infeld dilaton charged black hole. We have obtained analytical expressions for the absorption cross section as well as for the decay rate for the scalar field in the aforementioned spacetime, and we have shown graphically its behavior for different values of the free parameters of the theory.

hep-th↗

arXiv2017

On the null energy condition in scale dependent frameworks with spherical symmetry

The effect of a scale dependent newton coupling, which is a crucial ingredient of many quantum gravity theories, is investigated in this paper. For case of non-rotating black holes, and using the null energy condition, we show that Newtons scale dependent coupling can actually be obtained without solving the full quantum gap equations.

hep-th↗

arXiv2017

Scale dependent three-dimensional charged black holes in linear and non-linear electrodynamics

In the present work we study the scale dependence at the level of the effective action of charged black holes in Einstein-Maxwell as well as in Einstein-power-Maxwell theories in (2+1)-dimensional spacetimes without a cosmological constant. We allow for scale dependence of the gravitational and electromagnetic couplings, and we solve the corresponding generalized field equations imposing the "null energy condition". Certain properties, such as horizon structure and thermodynamics, are discussed in detail.

hep-th↗