scholarly journals Nonlinear electrodynamics effects on the black hole shadow, deflection angle, quasinormal modes and greybody factors

2022 ◽  
Vol 2022 (01) ◽  
pp. 009
Author(s):  
M. Okyay ◽  
A. Övgün
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Deflection Angle ◽  
Magnetic Charge ◽  
Generalized Uncertainty Principle ◽  
Quasinormal Modes ◽  
Nonlinear Electrodynamics ◽  
Stable Region ◽  
Massless Scalar ◽  
The Deflection Angle

Abstract In this paper, we discuss the effects of nonlinear electrodynamics (NED) on non-rotating black holes, parametrized by the field coupling parameter β and magnetic charge parameter P in detail. Particularly, we survey a large range of observables and physical properties of the magnetically charged black hole, including the thermodynamic properties, observational appearance, quasinormal modes and absorption cross sections. Initially, we show that the NED black hole is always surrounded by an event horizon and any magnetic charge is permissible. We then show that the black hole gets colder with increasing charge. Investigating the heat capacity, we see that the black hole is thermally stable between points of phase transition. Introducing a generalized uncertainty principle (GUP) with a quantum gravity parameter λ extends the range of the stable region, but the effect on temperature is negligible. Then we compute the deflection angle at the weak field limit, by the Gauss-Bonnet theorem and the geodesic equation, and find that even at the first order, the magnetic charge has a contribution due to the “field mass” term. Small changes of the charge contributes greatly to the paths of null geodesics due to the P 2 dependence of the horizon radius. Using a ray-tracing code, we simulate the observational appearance of a NED black hole under different emission profiles, thin disk and spherical accretion. We find that the parameter P has a very strong effect on the observed shadow radius, in agreement with the deflection angle calculations. We finally consider quasinormal modes under massless scalar perturbations of the black hole and the greybody factor. We find that the charge introduces a slight difference in the fundamental frequency of the emitted waveform. We find that the greybody factor of the NED black hole is strongly steepened by the introduction of increasing charge. To present observational constrains, we show that the magnetic charge of the M87* black hole is between 0 ≤ P ≤ 0.024 in units of M, in agreement with the idea that real astrophysical black holes are mostly neutral. We also find that LIGO/VIRGO and LISA could detect NED black hole perturbations from BHs with masses between 5 M ☉ and 8.0 · 108 M ☉. We finally show that for black holes with masses detected with LIGO so far, charged NED black holes would deviate from Schwarzschild by 5∼10 Hz in their fundamental frequencies.

Extended GUP corrected thermodynamics, shadow radius and quasinormal modes of charged AdS black holes in Gauss–Bonnet gravity

2021 ◽  
pp. 2150137
Author(s):  
Shahid Chaudhary ◽  
Abdul Jawad ◽  
Kimet Jusufi ◽  
Muhammad Yasir
Keyword(s):  
Black Hole ◽  
Generalized Uncertainty Principle ◽  
Quasinormal Modes ◽  
Nonlinear Electrodynamics ◽  
Horizon Radius ◽  
Bonnet Gravity ◽  
Ads Black Holes ◽  
Dimensional Black Hole ◽  
Relationship Of ◽  
The Relationship

This paper explores the influence of special type of higher order generalized uncertainty principle on the thermodynamics of five-dimensional black hole in Einstein–Gauss–Bonnet gravity coupled to nonlinear electrodynamics. We examine the corrected thermodynamical properties of the black hole with some interesting limiting cases [Formula: see text] and [Formula: see text] and compared our results with usual thermodynamical relations. We observe that the influence of GUP correction stabilizes the BH and BH solution remains physical throughout the region of horizon radius. In this framework, we also uncover the relationship of shadow radius and quasinormal modes of the mentioned black hole. We conclude that shadow radius of our considered black hole is a perfect circle and it decreases with increasing values of charge and Gauss–Bonnet parameter. We also verify the inverse relation between the quasinormal modes frequencies and shadow radius, i.e. quasinormal modes should increase with increasing values of Gauss–Bonnet parameter and electric charge.

scholarly journals Weak Deflection Angle of some Classes of non-linear Electrodynamics Black Holes via Gauss-Bonnet Theorem

2020 ◽  
Author(s):  
Hasan El Moumni ◽  
Karima Masmar ◽  
Ali Övgün
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Lensing ◽  
Deflection Angle ◽  
Weak Field ◽  
Leading Order ◽  
Plasma Medium ◽  
Non Linear ◽  
The Deflection Angle ◽  
Bonnet Theorem

In this paper, we study the gravitational lensing by some black hole classes within the non-linear electrodynamics in weak field limits. First, we calculate an optical geometry of the non-linear electrodynamics black hole then we use the Gauss-Bonnet theorem for finding deflection angle in weak field limits. The effect of non-linear electrodynamics on the deflection angle in leading order terms is studied. Furthermore, we discuss the effects of the plasma medium on the weak deflection angle.

Dyonic and Magnetic Black Holes with Rational Nonlinear Electrodynamics

2020 ◽  
Author(s):  
Sergey Kruglov
Keyword(s):  
Black Holes ◽  
Heat Capacity ◽  
Black Hole ◽  
Free Energy ◽  
Phase Transitions ◽  
Helmholtz Free Energy ◽  
Magnetic Charge ◽  
The Self ◽  
Nonlinear Electrodynamics ◽  
Dual Case

The principles of causality and unitarity are studied within rational nonlinear electrodynamics proposed earlier. We investigate dyonic and magnetized black holes and show that in the self-dual case, when the electric charge equals the magnetic charge, corrections to Coulomb's law and Reissner-Nordstrom solutions are absent. In the case of the magnetic black hole, the Hawking temperature, the heat capacity and the Helmholtz free energy are calculated. It is shown that there are second-order phase transitions and it was demonstrated that at some range of parameters the black holes are stable.

scholarly journals Effect of the Dilaton Field on Deflection Angle of Massive Photons by Black Holes in Einstein-Maxwell-Dilaton-Axion Theory

2019 ◽  
Author(s):  
Wajiha Javed ◽  
Rimsha Babar ◽  
Ali Övgün
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Deflection Angle ◽  
Weak Field ◽  
Dilaton Field ◽  
Plasma Medium ◽  
The Deflection Angle ◽  
Bonnet Theorem ◽  
Massive Photons

In this paper, we argue that one can calculate the weak deflection angle in the background of Einstein-Maxwell-Dilaton-Axion black hole using the Gauss-Bonnet theorem. To support this, the optical geometry of the black hole with the Gibbons-Werner method are used to obtain the deflection angle of light in the weak field limits. Moreover, we investigate the effect of a plasma medium on deflection of light for a given black hole. Because of dilaton and axion are one of the candidate of the dark matter, it can give us a hint on observation of dark matter which is supported the black hole. Hence we demonstrate the observational viability via showing the effect of the dark matter on the weak deflection angle.

scholarly journals The shadow of M87∗ black hole within rational nonlinear electrodynamics

2020 ◽  
Vol 35 (35) ◽  
pp. 2050291
Author(s):  
S. I. Kruglov
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Event Horizon ◽  
Magnetic Charge ◽  
Nonlinear Electrodynamics ◽  
Black Hole Mass

We consider rational nonlinear electrodynamics with the Lagrangian [Formula: see text] ([Formula: see text] is the Lorentz invariant), proposed in Ref. 63, coupled to General Relativity. The effective geometry induced by nonlinear electrodynamics corrections are found. We determine shadow’s size of regular non-rotating magnetic black holes and compare them with the shadow size of the super-massive M87[Formula: see text] black hole imaged by the Event Horizon Telescope collaboration. Assuming that the black hole mass has a pure electromagnetic nature, we obtain the black hole magnetic charge. The size of the shadow obtained is very close to the shadow size of non-regular neutral Schwarzschild black holes. As a result, we can interpret the super-massive M87[Formula: see text] black hole as a regular (without singularities) magnetized black hole.

scholarly journals Scalar waves in regular Bardeen black holes: Scattering, absorption and quasinormal modes

2016 ◽  
Vol 25 (09) ◽  
pp. 1641008 ◽  
Author(s):  
Caio F. B. Macedo ◽  
Luís C. B. Crispino ◽  
Ednilton S. de Oliveira
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cross Section ◽  
Absorption Cross Section ◽  
Quasinormal Modes ◽  
Scalar Fields ◽  
Scattering Cross Section ◽  
Massless Scalar ◽  
Absorption Cross ◽  
Scattering Cross

We discuss the phenomenology of massless scalar fields around a regular Bardeen black hole, namely absorption cross-section, scattering cross-section and quasinormal modes. We compare the Bardeen and Reissner–Nordström black holes, showing limiting cases for which their properties are similar.

scholarly journals 4d Einstein-Gauss-Bonnet Gravity With Nonlinear Electrodynamics: Entropy, Energy Emission, Quasinormal Modes and Deflection Angle

2021 ◽  
Author(s):  
Sergey Il'ich Kruglov
Keyword(s):  
Black Holes ◽  
Deflection Angle ◽  
Quasinormal Modes ◽  
Einstein Equations ◽  
Nonlinear Electrodynamics ◽  
Energy Conditions ◽  
Model Parameters ◽  
Logarithmic Correction ◽  
Bonnet Gravity ◽  
Energy Emission

The logarithmic correction to Bekenshtein-Hawking entropy in the framework of 4D Einstein$-$Gauss$-$Bonnet gravity coupled with nonlinear electrodynamics is obtained. We explore the black hole solution with the spherically symmetric metric. The logarithmic term in the entropy has a structure similar to the entropy correction in the semi-classical Einstein equations which mimics the quantum correction to the area low. The energy emission rate of black holes and energy conditions are studied. Quasinormal modes of black holes are investigated. The gravitational lensing of light around BHs was investigated. We calculated the deflection angle for some model parameters.

scholarly journals The Shadow of M87* Black Hole within Rational Nonlinear Electrodynamics

2020 ◽  
Author(s):  
Sergey Kruglov
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Event Horizon ◽  
Magnetic Charge ◽  
Nonlinear Electrodynamics

We consider rational nonlinear electrodynamics coupled to General Relativity. The effective geometry induced by nonlinear electrodynamics corrections are found. We determine shadows of regular non-rotating magnetic black holes and compare them with the shadow of the super-massive M87* black hole imaged by the Event Horizon Telescope collaboration. This allows us to obtain the black hole magnetic charge. The size of the shadow is very close to the shadow of non-regular neutral Schwarzschild black holes. As a result, we can interpret the super-massive M87* black hole as a regular (without singularities) magnetized black hole.

scholarly journals Deflection Angle of Photon from Magnetized Black Hole and Effect of Nonlinear Electrodynamics

2019 ◽  
Author(s):  
Wajiha Javed ◽  
jameela Abbas ◽  
Ali Övgün
Keyword(s):  
Black Hole ◽  
Deflection Angle ◽  
Weak Limit ◽  
Nonlinear Electrodynamics ◽  
Leading Order ◽  
Hole Charge ◽  
The Deflection Angle ◽  
Bonnet Theorem ◽  
Limit Approximation ◽  
Optical Metric

In this paper, we proposed a new model of non-linear electrodynamics with parameter. Firstly, we study the weak limit approximation and by using the Gauss Bonnet theorem, we obtain the deflection angle of photon from magnetized black hole and effect of bnon-linear electrodynamics. In doing so, we find the corresponding optical metric after that we calculate the Gaussian curvature which is used in Gauss Bonnet theorem. Then we show the deflection angle in the leading order terms. We also analyzed that our results reduces into Maxwell's electrodynamics and RN solution with the reduction of parameters. Moreover, we also investigate the graphical behavior of deflection angle w.r.t correction parameter, black hole charge and impact parameter.

Scalar and Dirac quasinormal modes of the scalar-tensor-Gauss-Bonnet black holes

2021 ◽  
Author(s):  
Tongzheng Wang ◽  
Wei-Liang Qian ◽  
Juan Fernando Zapata Zapata ◽  
Kai Lin
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Black Hole Solution ◽  
Magnetic Charge ◽  
Quasinormal Modes ◽  
Analytic Solutions ◽  
Adm Mass ◽  
Black Hole Spacetimes ◽  
Different Types ◽  
The Stability

Abstract This work explores the scalar and Dirac quasinormal modes pertaining to a class of black hole solutions in the scalar-tensor-Gauss-Bonnet theory. The black hole metrics in question are novel analytic solutions recently derived in the extended version of the latter theory, which effectively follows at the level of the action of string theory. Owing to the existence of a nonlinear electromagnetic field, the black hole solution possesses a nonvanishing magnetic charge. In particular, the metric is capable of describing black holes with distinct characteristics by assuming different values of the ADM mass and the magnetic charge. The present study is devoted to investigating the scalar and Dirac perturbations in the above black hole spacetimes, and in particular, based on distinct horizon structures, we focus on two different types of solutions. The properties of the complex frequencies of the obtained dissipative oscillations are investigated, and subsequently, the stability of the metric is addressed. We elaborate on the possible implications of the present study.

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