arXiv subjects

M. L. Peñafiel

Publications and source records attributed to M. L. Peñafiel.

7 recordsLinked to original sources

arXiv2025

Thermodynamical and dynamical stability of Einstein-Maxwell and extremal Einstein-Born-Infeld thin shells in $(2\ \mathbf{+}\ 1)$ dimensions

We study the dynamical and thermodynamical stability of thin shells in (2+1)-dimensional spacetimes composed of an inner anti-de Sitter (AdS) region and an outer region described by a charged Bañados--Teitelboim--Zanelli (BTZ) spacetime, sourced either by Einstein--Maxwell theory (Maxwell-BTZ) or Einstein--Born--Infeld theory (BI-BTZ). Assuming a fixed charge-to-mass ratio and modeling the shell's matter with a linear equation of state, we introduce a convenient parametrization to analyze the dynamical stability configurations. We find that Maxwell-BTZ thin shells admit a wider range of dynamically stable configurations compared to BI-BTZ thin shells. We also derive the thermodynamics of the shell matter, obtaining physically meaningful entropy functions in both cases, and examine the conditions for thermodynamical stability. In the Maxwell-BTZ case, we identify regions in the parameter space where configurations are both dynamically and thermodynamically stable. In contrast, for extremal BI-BTZ thin shells, all thermodynamically stable configurations are contained within the dynamically stable ones, and shells with a linear equation of state are always dynamically stable. This work extends the understanding of thin shell configurations in lower-dimensional gravity and elucidates the interplay between dynamics, thermodynamics, and nonlinear electrodynamics.

gr-qc↗

arXiv2025

Scattering and absorption of massless scalar waves by a ModMax black hole

ModMax electrodynamics is a remarkable example of nonlinear electrodynamics that preserves both conformal and duality invariance. When coupled to General Relativity, the resulting black hole solutions introduce a tunable nonlinearity parameter that effectively screens the electromagnetic charge. We study the scattering and absorption of massless scalar waves by a ModMax black hole by applying the partial waves method. We also compute some well-known analytical approximations for the scattering and absorption cross sections and contrast them with the full numerical solution. Our results adequately reproduce those of Maxwell electrodynamics in the appropriate limit and illustrate the effect of the charge screening in ModMax electrodynamics.

gr-qc↗

arXiv2024

On the radiation field of a linearly accelerated charged particle in Born-Infeld theory

The electric potential and the electromagnetic field for a linearly accelerated Born-Infeld charged particle are obtained in an inertial frame by a method that can, in principle, be applied to any electromagnetic theory. The method is based on (i) the fact that the metric near the horizon of a Schwarzschild black hole is equivalent to that of Rindler spacetime, and (ii) a theorem that guarantees that the electrostatic potential for a given nonlinear theory in a static, spherically symmetric spacetime is entirely specified by the Maxwellian electrostatic potential in the same background. Using analytical and numerical methods, the features of the radiation field and the radiation-reaction for such an accelerated particle are discussed in detail.

gr-qc↗

arXiv2021

Entropy bound in Einstein-Born-Infeld black holes

We study the validity of Bekenstein's entropy bound for a charged black hole in the context of nonlinear electrodynamics. Bekenstein's inequalities are commonly understood as universal relations between the entropy, the charge, the momentum, and the energy of a physical system but independent of its dynamics. In particular, we consider the Born-Infeld electrodynamics coupled to gravity as described by General Relativity. Following the steps that lead to these inequalities, we study the absorption of a charged test particle by the black hole and verify that the entropy bound is violated. We find a modified upper bound for the entropy that depends on the maximum field parameter of the Born-Infeld theory.

gr-qc↗

arXiv2020

Epidemiological projections for COVID-19 considering lockdown policies and social behavior: the case of Bolivia

We assess the epidemic situation caused by SARS-CoV-2 using Tsallis' proposal for determining the occurrence of the peak, and also the Susceptible-Infected-Recovered-Asymptomatic-Symptomatic and Dead (\textbf{SIRASD}) compartmental model. Using these two models, we determine a range of probable peak dates and study several social distancing scenarios during the epidemic. Due to the socioeconomic situation and the conflictive political climate, we take for our study the case of Bolivia, where a national election was originally scheduled to occur on September 6th and recently rescheduled on October 18th. For this, we analyze both electoral scenarios and show that such an event can largely affect the epidemic's dynamics.

physics.soc-ph↗

arXiv2019

Entropy bounds and nonlinear electrodynamics

Bekenstein's inequality sets a bound on the entropy of a charged macroscopic body. Such a bound is understood as a universal relation between physical quantities and fundamental constants of nature that should be valid for any physical system. We reanalyze the steps that lead to this entropy bound considering a charged object in conformity to Born-Infeld electrodynamics and show that the bound depends of the underlying theory used to describe the physical system. Our result shows that the nonlinear contribution to the electrostatic self-energy causes a raise in the entropy bound. As an intermediate step to obtain this result, we exhibit a general way to calculate the form of the electric field for a given nonlinear electrodynamics in Schwarzschild spacetime.

gr-qc↗

arXiv2017

Bekenstein Inequalities and Nonlinear Electrodynamics

Bekenstein and Mayo proposed a generalised bound for the entropy, which implies some inequalities between the charge, energy, angular momentum, and the size of the macroscopic system. Dain has shown that Maxwell's electrodynamics satisfies all three inequalities. We investigate the validity of these relations in the context of nonlinear electrodynamics and show that Born-Infeld electrodynamics satisfies all of them. However, contrary to the linear theory, there is no rigidity statement in Born-Infeld. We study the physical meaning and the relationship between these inequalities and, in particular, we analyse the connection between the energy-angular momentum inequality and causality.

gr-qc↗