scholarly journals Light deflection and Gauss–Bonnet theorem: definition of total deflection angle and its applications

2018 ◽  
Vol 50 (5) ◽  
Author(s):  
Hideyoshi Arakida
Keyword(s):  
Deflection Angle ◽  
Light Deflection ◽  
Definition Of ◽  
Bonnet Theorem

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 The Effects of Finite Distance on the Gravitational Deflection Angle of Light

Universe ◽  
2019 ◽  
Vol 5 (11) ◽  
pp. 218 ◽  
Author(s):  
Toshiaki Ono ◽  
Hideki Asada
Keyword(s):  
Deflection Angle ◽  
Short Review ◽  
Light Deflection ◽  
Sagittarius A ◽  
Distance Effects ◽  
Gravitational Deflection Of Light ◽  
Finite Distance ◽  
Definition Of ◽  
Distance Limit ◽  
Gravitational Deflection

In order to clarify the effects of the finite distance from a lens object to a light source and a receiver, the gravitational deflection of light has been recently reexamined by using the Gauss–Bonnet (GB) theorem in differential geometry (Ishihara et al. 2016). The purpose of the present paper is to give a short review of a series of works initiated by the above paper. First, we provide the definition of the gravitational deflection angle of light for the finite-distance source and receiver in a static, spherically symmetric and asymptotically flat spacetime. We discuss the geometrical invariance of the definition by using the GB theorem. The present definition is used to discuss finite-distance effects on the light deflection in Schwarzschild spacetime for both the cases of weak deflection and strong deflection. Next, we extend the definition to stationary and axisymmetric spacetimes. We compute finite-distance effects on the deflection angle of light for Kerr black holes and rotating Teo wormholes. Our results are consistent with the previous works if we take the infinite-distance limit. We briefly mention also the finite-distance effects on the light deflection by Sagittarius A * .

scholarly journals The Celestial Reference System in Relativistic Framework

1990 ◽  
Vol 141 ◽  
pp. 99-110
Author(s):  
Han Chun-Hao ◽  
Huang Tian-Yi ◽  
Xu Bang-Xin
Keyword(s):  
Coordinate System ◽  
Reference Frame ◽  
Reference System ◽  
Light Deflection ◽  
Coordinate Systems ◽  
Definition Of ◽  
Celestial Sphere ◽  
Celestial Reference System ◽  
Relativistic Framework

The concept of reference system, reference frame, coordinate system and celestial sphere in a relativistic framework are given. The problems on the choice of celestial coordinate systems and the definition of the light deflection are discussed. Our suggestions are listed in Sec. 5.

Design of freeform LED lens with large light deflection angle for road lighting application

2012 ◽  
Author(s):  
Shaoyun Yin ◽  
Zhongxun Wang ◽  
Xiuhui Sun ◽  
Liangping Xia ◽  
Hui Pang ◽  
...  
Keyword(s):  
Deflection Angle ◽  
Light Deflection ◽  
Road Lighting ◽  
Lighting Application

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.

On strong field deflection angle by the massless Ellis–Bronnikov wormhole

2019 ◽  
Vol 34 (05) ◽  
pp. 1950040 ◽  
Author(s):  
Amrita Bhattacharya ◽  
Alexander A. Potapov
Keyword(s):  
Gravity Field ◽  
Deflection Angle ◽  
Strong Field ◽  
Spherically Symmetric ◽  
Light Deflection ◽  
Massless Limit ◽  
Strong Gravity

Tsukamoto [N. Tsukamoto, Phys. Rev. D 95, 064035 (2017)] developed a method, which is an improvement over that of Bozza [V. Bozza, Phys. Rev. D 66, 103001 (2002)], for calculating light deflection angle in the strong gravity field of a spherically symmetric static spacetime. The method is directly applicable to the massless Ellis–Bronnikov wormhole (EBWH), while Bozza’s method is not applicable. We wish to show that it is still possible to obtain the same deflection angle by applying Bozza’s method but only in an indirect way, that is, first calculate the deflection by the parent massive EBWH and then take its massless limit.

scholarly journals Deflection angle of light by wormholes using the Gauss–Bonnet theorem

2017 ◽  
Vol 14 (12) ◽  
pp. 1750179 ◽  
Author(s):  
Kimet Jusufi
Keyword(s):  
Deflection Angle ◽  
Weak Limit ◽  
Space Time ◽  
Geometrical Method ◽  
Optical Geometry ◽  
The Deflection Angle ◽  
Bonnet Theorem ◽  
Limit Approximation

In this paper, we have investigated the deflection angle of light by wormholes using a new geometrical method known as Gibbons–Werner method (GW). In particular, we have calculated the deflection angle of light in the weak limit approximation in two wormhole space–time geometries: Ellis wormhole and Janis–Newman–Winnicour (JNW) wormhole. We have employed the famous Gauss–Bonnet theorem (GBT) to the Ellis wormhole optical geometry and JNW wormhole optical geometry, respectively. By using GBT, we computed the deflection angles in leading orders by these wormholes and our results were compared with the ones in the literature.

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

Here we calculate the deflection angle of photon by Casimir wormhole in weak limit approximation. First we calculate Gaussian optical curvature with the help of optical spacetime geometry and so we use the Gauss-Bonnet theorem on Gaussian optical metric and find 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. After calculating the deflection angle of Casimir wormhole. Now, 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 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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