scholarly journals Effect of the Magnetic Charge on Weak Deflection Angle and Greybody Bound of the Black Hole in Einstein-Gauss-Bonnet Gravity

2021 ◽  
Author(s):  
Wajiha Javed ◽  
Muhammad Aqib ◽  
Ali Övgün
Keyword(s):  
Deflection Angle ◽  
Magnetic Charge ◽  
Weak Field ◽  
Einstein Gravity ◽  
Plasma Medium ◽  
Field Limit ◽  
Bonnet Gravity ◽  
Weak Field Limit ◽  
Rigorous Bounds ◽  
Bonnet Theorem

The objective of this paper is to analyze the weak deflection angle of Einstein-Gauss-Bonnet gravity in the presence of plasma medium. To attain our results, we implement the Gibbons and Werner approach and use the Gauss-Bonnet theorem to Einstein gravity to acquire the resulting deflection angle of photon's ray in the weak field limit. Moreover, we illustrate the behavior of plasma medium and non-plasma mediums on the deflection of photon's ray in the framework of Einstein-Gauss-Bonnet gravity. Similarly, we observe the graphical influences of deflection angle on Einstein-Gauss-Bonnet gravity with the consideration of both plasma and non-plasma mediums. Later, we observe the rigorous bounds phenomenon of the greybody factor in contact with Einstein-Gauss-Bonnet gravity and calculate the outcomes, analyze graphically for specific values of parameters.

scholarly journals Weak Deflection Angle by Casimir Wormhole Using Gauss-Bonnet Theorem and Its Shadow

2020 ◽  
Author(s):  
Wajiha Javed ◽  
Ali Hamza ◽  
Ali Övgün
Keyword(s):  
Deflection Angle ◽  
Weak Field ◽  
Plasma Medium ◽  
Field Limit ◽  
Spacetime Geometry ◽  
Weak Field Limit ◽  
The Deflection Angle ◽  
Bonnet Theorem ◽  
Limit Approximation ◽  
Optical Metric

In this paper, we calculate the deflection angle of photon by Casimir wormhole in the weak field limit approximation. First we calculate Gaussian optical curvature with the help of optical spacetime geometry and so we use the Gauss-Bonnet theorem on the Gaussian optical metric. Then we find the deflection angle of photon by Casimir wormhole. Moreover, we calculate the photon's deflection angle in the presence of plasma medium and we also see the graphical nature of deflection angle in both cases. Second, we move towards the shadow of Casimir wormhole. After the observations of Event Horizon Telescope, the study of shadow become very important so that we plot the shapes of shadow of Casimir wormhole, and we calculate the photon geodesic around the Casimir wormhole.

scholarly journals Bounding Greybody and Weak Deflection Angle of NED Black Holes with Many Horizons

2021 ◽  
Author(s):  
Wajiha Javed ◽  
Iqra Hussain ◽  
Ali Övgün
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Deflection Angle ◽  
Weak Field ◽  
Plasma Medium ◽  
Weak Field Limit ◽  
Hole Charge ◽  
Bonnet Theorem ◽  
Grey Body ◽  
Optical Metric

In this project, our foremost intention is to analyze the angle of deflection of photon by NED black holes with many horizons in the context of non-linear electrodynamics. For the accomplishment of our intention at first we manipulated the optical metric of the desired black holes for the calculation of Gaussian curvature. After that, the angle of deflection in leading orders is attained from the desired black holes in weak field limit by using the famous Gauss-Bonnet theorem. Moreover, we evince the effect of plasma medium on the angle of deflection. At last, the graphical impact of the angle of deflection for NED black holes with many horizons is examined with respect to black hole charge and impact parameter in both the plasma and non plasma medium. In addition, we discuss the rigorous bound for grey body factor of the desired black hole and also observer its graphical behavior.

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.

scholarly journals Effect of Horndeski Theory on Weak Deflection Angle Using the Gauss-Bonnet Theorem

2021 ◽  
Author(s):  
Ali Övgün ◽  
Yashmitha Kumaran ◽  
Wajiha Javed ◽  
Jameela Abbas
Keyword(s):  
Black Hole ◽  
Gravitational Lensing ◽  
Deflection Angle ◽  
Field Approximation ◽  
Weak Field ◽  
Plasma Medium ◽  
The Deflection Angle ◽  
Bonnet Theorem ◽  
The Impact ◽  
Do So

The main goal of this paper is to study the weak gravitational lensing by Horndeski black hole in weak field approximation. In order to do so, we exploit the Gibbons-Werner method to the optical geometry of Horndeski black hole and implement the Gauss-Bonnet theorem to accomplish the deflection angle of light in weak field region. Furthermore, we have endeavored to extend the scale of our work by comprising the impact of plasma medium on the deflection angle as properly. Later, the graphical influence of the deflection angle of photon on Horndeski black hole in plasma and non-plasma medium is examined.

scholarly journals The Effect of the Brane-Dicke Coupling Parameter on Weak Gravitational Lensing by  Wormholes and Naked Singularities

2019 ◽  
Author(s):  
Wajiha Javed ◽  
Rimsha Babar ◽  
Ali Övgün
Keyword(s):  
Gravitational Lensing ◽  
Deflection Angle ◽  
Coupling Parameter ◽  
Weak Field ◽  
Anisotropic Pressure ◽  
Naked Singularities ◽  
Weak Field Limit ◽  
The Deflection Angle ◽  
Geometric Techniques ◽  
Bonnet Theorem

In this paper, we analyze the deflection angle of light by Brane-Dicke wormhole in the weak field limit approximation to find the effect of the Brane-Dicke coupling parameter on the weak gravitation lensing. For this purpose, we consider new geometric techniques, i.e., Gauss-Bonnet theorem and optical geometry in order to calculate the deflection angle. Furthermore, we verify our results by considering the most familiar geodesic technique. Moreover, we establish the quantum corrected metric of Brane-Dicke wormhole by replacing the classical geodesic with Bohmian trajectories, whose matter source and anisotropic pressure are influenced by Bohmian quantum effects and calculate its quantum corrected deflection angle. Then, we calculate the deflection angle by naked singularities and compare with the result of wormhole's. Such a novel lensing feature might serve as a way to detect wormholes, naked singularities and also the evidence of Brane-Dicke theory.

scholarly journals Weak deflection angle by asymptotically flat black holes in Horndeski theory using Gauss–Bonnet theorem

2020 ◽  
Vol 18 (01) ◽  
pp. 2150003
Author(s):  
Wajiha Javed ◽  
Jameela Abbas ◽  
Yashmitha Kumaran ◽  
Ali Övgün
Keyword(s):  
Black Holes ◽  
Gravitational Lensing ◽  
Deflection Angle ◽  
Weak Field ◽  
Plasma Medium ◽  
Asymptotically Flat ◽  
Optical Geometry ◽  
Principal Objective ◽  
The Deflection Angle ◽  
Bonnet Theorem

The principal objective of this project is to investigate the gravitational lensing by asymptotically flat black holes in the framework of Horndeski theory in weak field limits. To achieve this objective, we utilize the Gauss–Bonnet theorem to the optical geometry of asymptotically flat black holes and apply the Gibbons–Werner technique to achieve the deflection angle of photons in weak field limits. Subsequently, we manifest the influence of plasma medium on deflection of photons by asymptotically flat black holes in the context of Horndeski theory. We also examine the graphical impact of deflection angle on asymptotically flat black holes in the background of Horndeski theory in plasma medium as well as non-plasma medium.

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 Effect of Horndeski Theory on Weak Deflection Angle Using the Gauss-Bonnet Theorem

2021 ◽  
Author(s):  
Ali Övgün ◽  
Yashmitha Kumaran ◽  
Wajiha Javed ◽  
Jameela Abbas
Keyword(s):  
Black Hole ◽  
Gravitational Lensing ◽  
Deflection Angle ◽  
Field Approximation ◽  
Weak Field ◽  
Plasma Medium ◽  
The Deflection Angle ◽  
Bonnet Theorem ◽  
The Impact ◽  
Do So

The main goal of this paper is to study the weak gravitational lensing by Horndeski black hole in weak field approximation. In order to do so, we exploit the Gibbons-Werner method to the optical geometry of Horndeski black hole and implement the Gauss-Bonnet theorem to accomplish the deflection angle of light in weak field region. Furthermore, we have endeavored to extend the scale of our work by comprising the impact of plasma medium on the deflection angle as properly. Later, the graphical influence of the deflection angle of photon on Horndeski black hole in plasma and non-plasma medium is examined.

scholarly journals Weak deflection angle by Casimir wormhole using Gauss-Bonnet theorem and its shadow

2020 ◽  
Vol 35 (39) ◽  
pp. 2050322
Author(s):  
Wajiha Javed ◽  
Ali Hamza ◽  
Ali Övgün
Keyword(s):  
Deflection Angle ◽  
Weak Field ◽  
Plasma Medium ◽  
The Deflection Angle ◽  
Bonnet Theorem ◽  
Do So

In this paper, we calculate the weak deflection angle by Casimir wormhole and its shadow. To do so, we derive the Gaussian optical curvature and use the Gauss–Bonnet theorem (GBT). Then we find the deflection angle by Casimir wormhole in weak field limits. Moreover, we obtain the weak deflection angle in the presence of plasma medium and see the effect of the plasma medium on the weak deflection angle. Moreover, we study a shadow of Casimir wormhole and we plot and discuss them. We show the shadow of Casimir wormhole’s behavior when changing the value of a.

scholarly journals Weak Deflection Angle and Shadow by Tidal Charged Black Hole

2021 ◽  
Author(s):  
Wajiha Javed ◽  
Ali Hamza ◽  
Ali Övgün
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Deflection Angle ◽  
Weak Field ◽  
Charged Black Hole ◽  
Plasma Medium ◽  
Null Geodesics ◽  
The Deflection Angle ◽  
Bonnet Theorem

In this article, we calculate the deflection angle of tidal charged black hole (TCBH) in weak field limits. First we obtain the Gaussian optical curvature and then apply the Gauss-Bonnet theorem on it. With the help of Gibbons-Werner method, we are able to calculate the light's deflection angle by TCBH in weak field limits. After calculating the deflection angle of light, we check the graphical behavior of TCBH. Moreover, we further find the light's deflection angle in the presence of plasma medium and also check the graphical behavior in the presence of plasma medium. Moreover, we investigate the shadow of TCBH.For calculating the shadow, we first find the null geodesics around the TCBH and then find its shadow radius. We also obtain TCBH's shadow in the plasma medium. Hence, we discuss the shadow of the TCBH using the $M87^{*}$ parameters announced by the Event Horizon Telescope.

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