arXiv subjects

Askar Ali

Publications and source records attributed to Askar Ali.

10 recordsLinked to original sources

arXiv2025

Exotic Lovelock black holes and extended quasitopological electromagnetism

The generalization of Birkhoff's theorem for higher dimensions in Lovelock gravity permits us to investigate the black hole solutions with horizon geometries of nonconstant curvature. We present a new class of exotic dyonic black holes in the context of Lovelock gravity and generalized quasitopological electromagnetism. First, we derive the polynomial equation that describes exotic dyonic black holes in Lovelock gravity with an arbitrary order. Next, the solutions that characterize dyonic exotic black holes of the Gauss-Bonnet and third order Lovelock gravities are worked out. Then we compute the basic thermodynamic quantities for these exotic dyonic black holes. It is also verified that these quantities satisfy the generalized first law and Smarr's relation. Furthermore, the impact of generalized quasitopological electromagnetism and topological parameters on the local stability of the resulting objects are also investigated.

gr-qc↗

arXiv2023

Topological dyonic black holes of massive gravity with generalized quasitopological electromagnetism

In this paper we investigate new dyonic black holes of massive gravity sourced by generalized quasitopological electromagnetism in arbitrary dimensions. We begin by deriving the exact solution to the field equations defining these black holes and look at how graviton's mass, dimensionality parameter, and quasitopological electromagnetic field affect the horizon structure of anti-de Sitter dyonic black holes. We also explore the asymptotic behaviour of the curvature invariants at both the origin and infinity to analyze the geometric structure of the resultant black holes. We also compute the conserved and thermodynamic quantities of these dyonic black holes with the help of established techniques and known formulas. After investigating the relevancy of first law, we look at how various parameters influence the local thermodynamic stability of resultant black hole solution. We also examine how thermal fluctuations affect the local stability of dyonic black holes in massive gravity. Finally, we study the shadow cast of the black hole.

gr-qc↗

arXiv2022

Power-Yang-Mills black holes and black branes in quartic quasi-topological gravity

We study higher dimensional quartic quasi-topological black holes in the framework of non-abelian power-Yang-Mills theory. It is shown that real solutions of the gravitational field equations exist only for positive values of quartic quasi-topological coefficient. Depending on the values of the mass parameter and Yang-Mills charge, they can be interpreted as black holes with one horizon, two horizons and naked singularity. It is also shown that the solution associated with these black holes has an essential curvature singularity at the centre $r=0$. Thermodynamic and conserved quantities for these black holes are computed and we show that the first law has been verified. We also check thermodynamic stability in both canonical and grand canonical ensembles. In addition to this, we also formulate new power-Yang-Mills black hole solutions in pure quasi-topological gravity. The physical and thermodynamic properties of these black holes are discussed as well. It is concluded that unlike Yang-Mills black holes there exist stability regions for smaller power-Yang-Mills black holes in grand canonical ensemble. Finally, we discuss the thermodynamics of horizon flat power-Yang-Mills rotating black branes and analyze their thermodynamic and conserved quantities by using the counter-term method inspired by AdS/CFT correspondence.

hep-th↗

arXiv2020

Magnetized hairy black holes of dimensionally continued gravity coupled to double-logarithmic electrodynamics

A recently proposed model for nonlinear electrodynamics has been minimally coupled to dimensionally continued gravity and the topological black holes in the presence of conformal scalar field were studied. In this setup, the new magnetized hairy black hole solution has been found and its thermodynamic properties have also been analyzed. The exact expressions for mass, entropy, Hawking temperature and heat capacity are derived and local thermodynamic stability for the resulting black holes has been checked. In addition to this, the modified Smarr's formula is constructed and the generalized first law has also been verified. Finally, the hairy magnetized black holes in general Lovelock-scalar gravity have also been studied.

gr-qc↗

arXiv2020

Energy-Dependent Topological Black Holes in Massive Gravity Coupled to Double-Logarithmic Electrodynamics

In this paper, I investigate the nonlinear magnetized black holes of massive gravity's rainbow. In order to achieve this, I use the double-logarithmic electromagnetic field as a matter source and derive the new anti-de Sitter black hole solution. The effects of the massive graviton, rainbow functions, and nonlinearity of the electromagnetic field on the black hole's inner and outer horizons are also studied. The black hole's thermodynamic properties are studied, and the mathematical expressions for temperature, heat capacity, and Gibbs free energy are found. The extended first law and Smarr's formula are derived as well. Using the behaviour of thermodynamic quantities as a starting point, I also study the local and global thermodynamic stabilities.

gr-qc↗

arXiv2020

Lovelock black holes with double-logarithmic electrodynamics source

This work examines the magnetized black holes of Lovelock gravity in the presence of double-logarithmic electrodynamics. In this context, the Lovelock polynomial is found and the accompanying thermodynamic quantities, such as mass, entropy, Hawking temperature, and heat capacity are determined. This new model of nonlinear electrodynamics is used to calculate the black hole solutions of Einstein, Gauss-Bonnet and third order Lovelock gravities as well. The impacts of the double-logarithmic electromagnetic field on the black hole thermodynamics in these particular theories are examined and the regions of horizon radius that correspond to the local thermodynamic stability are highlighted.

gr-qc↗

arXiv2020

Lovelock black holes surrounded by dark fluid in power-Yang-Mills massive gravity

We consider a model where massive static spherically symmetric black hole, in the presence of power-Yang-Mills source, is surrounded by a dark fluid with non-linear equation of state. In this set up we construct a new class of magnetized Lovelock black hole solutions of the gravitational field equations. In particular, we work out the metric functions in both D-dimensional massive Einstein and massive Gauss-Bonnet gravities. We study thermodynamics of these black holes also and show that the mass and associated thermodynamic quantities like Hawking temperature and heat capacity depend on parameters of the dark fluid and the power-Yang-Mills magnetic source. We note that the entropy does not satisfy the area law in Gauss-Bonnet and higher order Lovelock black holes. Furthermore, phase transitions of black holes in each case are also discussed.

gr-qc↗

arXiv2020

Lorentz symmetry violating BTZ black holes in massive gravity

BTZ black holes provide excellent frameworks for studying theories that are at the interface of classical and quantum gravity. In this paper we couple the Riemannian spacetime with the bumblebee field, in the background of massive gravity, which produces the violation of spontaneous Lorentz symmetry. In this setup we construct a large family of static vacuum BTZ black hole solutions. We study the asymptotic behaviour of curvature invariants and show that our resulting solutions describe asymptotically AdS (2+1)-dimensional BTZ black holes with negative cosmological constant. For positive cosmological constant they are de Sitter. Thermodynamics of these black holes is also analysed.

gr-qc↗

arXiv2019

Magnetized topological black holes of dimensionally continued gravity

In this paper, a large family of topological black hole solutions of dimensionally continued gravity are derived. The action of Lovelock gravity is coupled to the exponential electrodynamics and the equations of motion are solved in the presence of a pure magnetic source. We work out the metric functions in terms of the parameter $β$ of exponential electrodynamics, and magnetic charge. Further, we couple Lovelock gravity to power-Yang-Mills theory and construct black holes, in diverse dimensions, having Yang-Mills magnetic charge. We also discuss the asymptotic bahaviour of metric functions and curvature invariants at the origin for both the models. The thermodynamics of resulting magnetized black hole solutions in the framework of two different models is also studied. The thermodynamical quantities like Hawking temperature, entropy and specific heat capacity at constant charge are found and we show that the resulting quantities satisfy the first law of black hole thermodynamics. We also study the magnetized hairy black holes of dimensionally continued gravity.

gr-qc↗

arXiv2019

Asymptotic magnetically charged non-singular black hole and its thermodynamics

Some very interesting solutions of the field equations of Einstein's general theory of relativity have been constructed in the framework of nonlinear electrodynamics. In particular, magnetically charged black hole solutions in the framework of exponential nonlinear electrodynamics have been obtained in general relativity in Kruglov (2017). Using this approach a magnetically charged non-singular black hole spacetime in the framework of exponential electrodynamics in some modified theory of gravity has been constructed in this letter. The metric describing asymptotic non-singular magnetized black hole is worked out in terms of the parameter of our model. When this parameter vanishes our solution reduces to the above mentioned black hole solution. Thermodynamics of the resulting solution is also discussed by calculating the Hawking temperature and heat capacity when the magnetic charge is constant. We also find out the point where the first order phase transition induced by temperature changes takes place. The quantum radiations from this black hole are also discussed and the mathematical expression for the rate of energy flux of these radiations has been obtained.

gr-qc↗