scholarly journals Weak field deflection angle by regular black holes with cosmic strings using the Gauss-Bonnet theorem

2019 ◽  
Vol 99 (10) ◽  
Author(s):  
A. Övgün
Keyword(s):  
Black Holes ◽  
Deflection Angle ◽  
Cosmic Strings ◽  
Weak Field ◽  
Regular Black Holes ◽  
Bonnet Theorem

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.

Gravitational lensing by regular black holes surrounded by plasma

2017 ◽  
Vol 26 (05) ◽  
pp. 1741011 ◽  
Author(s):  
Ahmadjon Abdujabbarov ◽  
Bobir Toshmatov ◽  
Jan Schee ◽  
Zdeněk Stuchlík ◽  
Bobomurat Ahmedov
Keyword(s):  
Black Holes ◽  
Gravitational Lensing ◽  
Deflection Angle ◽  
Field Approximation ◽  
Weak Field ◽  
Source Image ◽  
Primary Ring ◽  
Regular Black Hole ◽  
Regular Black Holes ◽  
The Deflection Angle

In the weak field approximation, we study the gravitational lensing near the regular Bardeen, Hayward and Ayon-Beato–Garcia (ABG) black holes surrounded by plasma. The exact expressions for the deflection angle of the photons due to the effect of the gravitational field and the plasma have been obtained. The analysis of the image source brightness magnification in the background spacetimes of (i) Bardeen, (ii) Hayward and (iii) ABG regular black holes have shown that the increase of the corresponding charge of regular black hole causes the increase in the magnification of the source image. In addition to the primary ring, one may observe the secondary ring with smaller magnification. The influence of the plasma with (i) constant and (ii) radial power law electron density to the magnification of the source image has been studied.

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 Deriving Weak Deflection Angle by Black Holes or Wormholes using Gauss-Bonnet Theorem

2021 ◽  
Author(s):  
Yashmitha Kumaran ◽  
Ali Övgün
Keyword(s):  
Black Holes ◽  
Gravitational Lensing ◽  
Deflection Angle ◽  
Weak Field ◽  
Plasma Medium ◽  
Asymptotically Flat ◽  
Finite Distance ◽  
Flat Spacetimes ◽  
The Deflection Angle ◽  
Bonnet Theorem

In this review, various researches on finding the bending angle of light deflected by a massive gravitating object which regard the Gauss-Bonnet theorem as the premise have been revised. Primarily, the Gibbons and Werner method is studied apropos of the gravitational lensing phenomenon in the weak field limits. Some exclusive instances are deliberated while calculating the deflection angle, beginning with the finite-distance corrections on non-asymptotically flat spacetimes. Effects of plasma medium is then inspected to observe its contribution to the deflection angle. Finally, the Jacobi metric is explored as an alternative method, only to arrive at similar results. All of the cases are probed in three constructs, one as a generic statement of explanation, one for black holes, and one for wormholes, so as to gain a perspective on every kind of influence.

scholarly journals Testing Horndeski Theory Using Light Deflection by Asymptotically Flat Black Holes

2019 ◽  
Author(s):  
Wajiha Javed ◽  
Jameela Abbas ◽  
Yashmitha Kumaran ◽  
Ali Övgün
Keyword(s):  
Black Holes ◽  
Gravitational Lensing ◽  
Deflection Angle ◽  
Weak Field ◽  
Light Deflection ◽  
Plasma Medium ◽  
Asymptotically Flat ◽  
Optical Geometry ◽  
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 applying 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 as well as non-plasma medium.

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 by Asymptotically Flat Black Holes in Horndeski Theory Using Gauss-Bonnet Theorem

2020 ◽  
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 applying 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 as well as non-plasma medium.

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 Effect of Non-Linear Electrodynamics on Weak Field Deflection Angle by Black Hole

2020 ◽  
Author(s):  
Wajiha Javed ◽  
Ali Hamza ◽  
Ali Övgün
Keyword(s):  
Black Hole ◽  
Gravitational Lensing ◽  
Deflection Angle ◽  
Weak Field ◽  
Weak Limit ◽  
Spacetime Geometry ◽  
Weak Gravitational Field ◽  
Non Linear ◽  
The Deflection Angle ◽  
Bonnet Theorem

In this work, we investigate the weak deflection angle of light from exact black hole within the non-linear electrodynamics. First we calculate the Gaussian optical curvature using the optical spacetime geometry. With the help of modern geometrical way popularized by Gibbons and Werner, we examine the deflection angle of light from exact black hole. For this desire, we determine the optical Gaussian curvature and execute the Gauss-Bonnet theorem on optical metric and calculate the leading terms of deflection angle in the weak limit approximation. Furthermore, we likewise study the plasma medium's effect on weak gravitational lensing by exact black hole. Hence we expose the effect of the non-linear electrodynamics on the deflection angle in the weak gravitational field.

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