Papers by Ángel Téllez Rincón
The European Physical Journal C
In the present work, we investigate the consequences of running gravitational coupling on the pro... more In the present work, we investigate the consequences of running gravitational coupling on the properties of the three-dimensional BTZ black hole. We take as starting point the functional form of gravitational coupling obtained in the context of asymptotic safe gravity theory. By using the standard scale setting relation where $$k\sim \xi /r^n$$ k ∼ ξ / r n , we compute the solution of the Einstein field equations. We get and analyze the horizon and the thermodynamic properties of this new class of black hole solutions. The impact of the scale-dependent parameter $$\xi $$ ξ on the cosmological “constant” and metric functions are briefly discussed. We find that the null energy condition is also violated in this setup when scale-dependent gravity and Newton’s coupling (coming from the asymptotic safety scenario of gravity) are simultaneously taken into account.
The European Physical Journal C
In this work, the role of a time-varying Newton constant under the scale-dependent approach is in... more In this work, the role of a time-varying Newton constant under the scale-dependent approach is investigated in the thermodynamics of the Friedman equations. In particular, we show that the extended Friedman equations can be derived either from equilibrium thermodynamics when the non-matter energy momentum tensor is interpreted as a fluid or from non-equilibrium thermodynamics when an entropy production term, which depends on the time-varying Newton constant, is included. Finally, a comparison between black hole and cosmological thermodynamics in the framework of scale-dependent gravity is briefly discussed.
Physics of the Dark Universe, 2021
We show that the extended cosmological equation-of-state developed starting from a Chaplygin equa... more We show that the extended cosmological equation-of-state developed starting from a Chaplygin equation-of-state, recently applied to stellar modeling, is a viable dark energy model consistent with standard scalar potentials. Moreover we find a Lagrangian formulation based on a canonical scalar field with the appropriate self-interaction potential. Finally, we fit the scalar potential obtained numerically with concrete functions well studied in the literature. Our results may be of interest to model builders and particle physicists.
Physics of the Dark Universe, 2020
We study slowly rotating four-dimensional black holes with flat horizon structure in scale-depend... more We study slowly rotating four-dimensional black holes with flat horizon structure in scale-dependent gravity. First we obtain the solution, and then we study thermodynamic properties as well as the invariants of the theory. The impact of the scale-dependent parameter is investigated in detail. We find that the scale-dependent solution exhibits a single singularity at the origin, also present in the classical solution.
Universe, 2021
We study the impact of a non-vanishing (positive) cosmological constant on the innermost and oute... more We study the impact of a non-vanishing (positive) cosmological constant on the innermost and outermost stable circular orbits (ISCOs and OSCOs, respectively) within massive gravity in four dimensions. The gravitational field generated by a point-like object within this theory is known, generalizing the usual Schwarzschild–de Sitter geometry of General Relativity. In the non-relativistic limit, the gravitational potential differs by the one corresponding to the Schwarzschild–de Sitter geometry by a term that is linear in the radial coordinate with some prefactor γ, which is the only free parameter. Starting from the geodesic equations for massive test particles and the corresponding effective potential, we obtain a polynomial of fifth order that allows us to compute the innermost and outermost stable circular orbits. Next, we numerically compute the real and positive roots of the polynomial for several different structures (from the hydrogen atom to stars and globular clusters to gal...
Physics of the Dark Universe, 2021
In the present work, we extend and generalize our previous work regarding the scale dependence ap... more In the present work, we extend and generalize our previous work regarding the scale dependence applied to black holes in the presence of non-linear electrodynamics [1]. The starting point for this study is the Einstein-power-Maxwell theory with a vanishing cosmological constant in (3+1) dimensions, assuming a scale dependence of both the gravitational and the electromagnetic coupling. We further examine the corresponding thermodynamic properties and how these quantities experience deviations from their classical counterparts. We solve the effective Einstein's field equations using the "null energy condition" to obtain analytical solutions. The implications of quantum corrections are also briefly discussed. Finally, we analyze our solutions and compare them to related results in the literature.
Physics of the Dark Universe, 2020
We compute the quasinormal frequencies for scalar and electromagnetic perturbations of an improve... more We compute the quasinormal frequencies for scalar and electromagnetic perturbations of an improved Schwarzschild geometry in the framework of asymptotically safe gravity, which is one of the approaches to quantum gravity. Adopting the widely used WKB semi-classical approximation, we investigate the impact on the spectrum of the angular degree, the overtone number as well as the black hole mass. We summarize our numerical results in tables, and for better visualization, we show them graphically as well. All modes are found to be stable. Finally, we compare our numerical results with those corresponding to the classical Schwarzschild solution as well as to the results obtained using a different approach. Our findings show that i) a different cutoff identification does not affect the spectra significantly, and ii) for hypothetical objects with masses comparable to the Planck mass, the difference in the numerical values between the modes of the classical solution and the modes of the improved solution studied here is of the order of a few per cent. On the contrary, for realistic, astrophysical BHs no difference in the frequencies is observed.
The European Physical Journal C, 2021
We obtain well behaved interior solutions describing hydrostatic equilibrium of anisotropic relat... more We obtain well behaved interior solutions describing hydrostatic equilibrium of anisotropic relativistic stars in scale-dependent gravity, where Newton’s constant is allowed to vary with the radial coordinate throughout the star. Assuming (1) a linear equation-of-state in the MIT bag model for quark matter, and (2) a certain profile for the energy density, we integrate numerically the generalized structure equations, and we compute the basic properties of the strange quark stars, such as mass, radius and compactness. Finally, we demonstrate that stability criteria as well as the energy conditions are fulfilled. Our results show that a decreasing Newton’s constant throughout the objects leads to slightly more massive and more compact stars.
Annals of Physics, 2021
In this work, motivated by the fact that higher dimensional theories predict the existence of bla... more 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.95, 161301 (2005)), which has the Myers-Perry black hole as a limit.
The European Physical Journal C, 2020
We study relativistic stars in the scale-dependent scenario, which is one of the approaches to qu... more We study relativistic stars in the scale-dependent scenario, which is one of the approaches to quantum gravity, and where Newton’s constant is promoted to a scale-dependent quantity. First, the generalized structure equations are derived here for the first time. Then they are integrated numerically assuming a linear equation-of-state in the simplest MIT bag model for quark matter. We compute the radius, the mass and the compactness of strange quarks stars, and we show that the energy conditions are fulfilled.
Physics of the Dark Universe, 2021
We compute the quasinormal spectra for scalar, Dirac and electromagnetic perturbations of the Sch... more We compute the quasinormal spectra for scalar, Dirac and electromagnetic perturbations of the Schwarzschild-de Sitter geometry in the framework of scale-dependent gravity, which is one of the current approaches to quantum gravity. Adopting the widely used WKB semi-classical approximation, we investigate the impact on the spectrum of the angular degree, the overtone number as well as the scale-dependent parameter for fixed black hole mass and cosmological constant. We summarize our numerical results in tables, and for better visualization, we show them graphically as well. All modes are found to be stable. Our findings show that both the real part and the absolute value of the imaginary part of the frequencies increase with the parameter that measures the deviation from the classical geometry. Therefore, in the framework of scale-dependent gravity the modes oscillate and decay faster in comparison with their classical counterparts.
The European Physical Journal C, 2020
In the present paper, we analyze the well-known 2+1 dimensional black holes (assuming a non-vanis... more In the present paper, we analyze the well-known 2+1 dimensional black holes (assuming a non-vanishing cosmological constant) in light of the gravitational decoupling by the minimal geometric deformation approach. To illustrate our results, we consider the BTZ geometry as the seed solution to generate new anisotropic ones. To complement the study, the curvature scalars and the energy conditions are analyzed.
The European Physical Journal Plus, 2020
We investigate the properties of relativistic stars made of dark energy. We model stellar structu... more We investigate the properties of relativistic stars made of dark energy. We model stellar structure assuming i) isotropic perfect fluid and ii) a dark energy inspired equation of state, the generalized equation of state of Chaplygin gas, as we will be calling it. The mass-to-radius profiles, the tidal Love numbers as well as the ten lowest radial oscillation modes are computed. Causality, stability and energy conditions are also discussed. PACS. PACS-key discribing text of that key-PACS-key discribing text of that key
Physica Scripta, 2020
We compute the quasinormal frequencies for scalar perturbations of hairy black holes in fourdimen... more We compute the quasinormal frequencies for scalar perturbations of hairy black holes in fourdimensional Einstein-Maxwell-dilaton theory assuming a non-trivial scalar potential for the dilaton field. We investigate the impact on the spectrum of the angular degree, the overtone number, the charges of the black hole as well as the magnitude of the scalar potential. All modes are found to be stable. Our numerical results are summarized in tables, and for better visualization, we show them graphically as well.
Chinese Physics C, 2020
The present article reports the study of local anisotropic effects on Durgapal's fourth model... more The present article reports the study of local anisotropic effects on Durgapal's fourth model in the context of gravitational decoupling via the minimal geometric deformation approach. To achieve this, the most general equation of state relating the components of the θ−sector is imposed to obtain the decoupler function . In addition, certain properties of the obtained solution, such as the behavior of the salient material content threading the stellar interior; causality and energy conditions; hydrostatic balance through the modified Tolman−Oppenheimer−Volkoff conservation equation and stability mechanism against local anisotropies using the adiabatic index; sound velocity of the pressure waves; convection factor; and the Harrison−Zeldovich−Novikov procedure, are investigated to check whether the model is physically admissible or not. Regarding the stability analysis, it is found that the model presents unstable regions when the sound speed of the pressure waves and convection f...
Physical Review D, 2020
In this work, starting from a spherically symmetric scale-dependent black hole, a rotating soluti... more In this work, starting from a spherically symmetric scale-dependent 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 get and discuss the shape of its shadow.
The European Physical Journal C, 2020
In this work, we investigate five-dimensional scale-dependent black hole solutions by modelling t... more 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.
The European Physical Journal C, 2020
In this work, a spherically symmetric and static relativistic anisotropic fluid sphere solution o... more In this work, a spherically symmetric and static relativistic anisotropic fluid sphere solution of the Einstein field equations is provided. To build this particular model, we have imposed metric potential $$e^{2\lambda (r)}$$e2λ(r) and an equation of state. Specifically, the so-called modified generalized Chaplygin equation of state with $$\omega =1$$ω=1 and depending on two parameters, namely, A and B. These ingredients close the problem, at least mathematically. However, to check the feasibility of the model, a complete physical analysis has been performed. Thus, we analyze the obtained geometry and the main physical observables, such as the density $$\rho $$ρ, the radial $$p_{r}$$pr, and tangential $$p_{t}$$pt pressures as well as the anisotropy factor $$\Delta $$Δ. Besides, the stability of the system has been checked by means of the velocities of the pressure waves and the relativistic adiabatic index. It is found that the configuration is stable in considering the adiabatic i...
The European Physical Journal C, 2020
We study three interacting dark energy models within the framework of four-dimensional General Re... more 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 f...
The European Physical Journal Plus, 2020
We compute the spectrum of quasinormal frequencies of five-dimensional black holes obtained in no... more We compute the spectrum of quasinormal frequencies of five-dimensional black holes obtained in noncommutative geometry. In particular, we study scalar perturbations of a massive scalar field adopting the 6th order WKB approximation. We investigate in detail the impact of the mass of the scalar field, the angular degree and the overtone number on the spectrum. All modes are found to be stable.
Uploads
Papers by Ángel Téllez Rincón