scholarly journals Deflection Angle of Photon Through Dark Matter by Black Holes/Wormholes Using the Gauss-Bonnet Theorem

2019 ◽  
Author(s):  
Ali Övgün
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Near Field ◽  
Compact Objects ◽  
Weak Gravitational Lensing ◽  
Optical Geometry ◽  
Field Information ◽  
Bonnet Theorem ◽  
Fish Eye ◽  
Excellent Tool

Maxwell's fish eye has been known to be a perfect lens in optics. In this letter, using the Gibbons-Werner method, namely Gauss-Bonnet theorem on optical geometry of black hole, we extend the calculation of the weak gravitational lensing within the Maxwell's fisheye as a perfect lensing in medium composed of an isotropic refractive index that near-field information can be obtained from far-field distances. Moreover, these results provide an excellent tool to observe compact massive object by weak gravitational lensing within the dark matter medium and to understand the nature of the dark matter that may effect the gravitational waves. Moreover, we show that Gauss-Bonnet theorem is a global effect and this method can be used as a new tool on any optical geometry of compact objects in dark matter medium.

scholarly journals Deflection Angle of Photons through Dark Matter by Black Holes and Wormholes Using Gauss–Bonnet Theorem

Universe ◽  
2019 ◽  
Vol 5 (5) ◽  
pp. 115 ◽  
Author(s):  
Ali Övgün
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Gravitational Lensing ◽  
Deflection Angle ◽  
Compact Objects ◽  
Asymptotically Flat ◽  
Optical Geometry ◽  
Topological Effect ◽  
Bonnet Theorem ◽  
Fish Eye

In this research, we used the Gibbons–Werner method (Gauss–Bonnet theorem) on the optical geometry of a black hole and wormhole, extending the calculation of weak gravitational lensing within the Maxwell’s fish eye-like profile and dark-matter medium. The angle is seen as a partially topological effect, and the Gibbons–Werner method can be used on any asymptotically flat Riemannian optical geometry of compact objects in a dark-matter medium.

scholarly journals CFHTLenS: the relation between galaxy dark matter haloes and baryons from weak gravitational lensing

2013 ◽  
Vol 437 (3) ◽  
pp. 2111-2136 ◽  
Author(s):  
Malin Velander ◽  
Edo van Uitert ◽  
Henk Hoekstra ◽  
Jean Coupon ◽  
Thomas Erben ◽  
...  
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Weak Gravitational Lensing

scholarly journals Detection of weak gravitational lensing distortions of distant galaxies by cosmic dark matter at large scales

Nature ◽  
2000 ◽  
Vol 405 (6783) ◽  
pp. 143-148 ◽  
Author(s):  
David M. Wittman ◽  
J. Anthony Tyson ◽  
David Kirkman ◽  
Ian Dell'Antonio ◽  
Gary Bernstein
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Weak Gravitational Lensing ◽  
Distant Galaxies

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 Weak Gravitational Lensing—The Need for Surveys

1998 ◽  
Vol 179 ◽  
pp. 241-248
Author(s):  
P. Schneider
Keyword(s):  
Mass Distribution ◽  
Gravitational Lensing ◽  
Compact Objects ◽  
Gravitational Lens ◽  
Weak Lensing ◽  
Wide Field ◽  
Redshift Distribution ◽  
Weak Gravitational Lensing ◽  
Distant Galaxies ◽  
Galaxy Population

Light rays from distant sources are deflected if they pass near an intervening matter inhomogeneity. This gravitational lens effect is responsible for the well-established lens systems like multiple-imaged QSOs, (radio) ‘Einstein’ rings, the giant luminous arcs in clusters of galaxies, and the flux variations of stars in the LMC and the Galactic bulge seen in the searches for compact objects in our Galaxy. These types of lensing events are nowadays called ‘strong lensing,’ to distinguish it from the effects discussed here: light bundles are not only deflected as a whole, but distorted by the tidal gravitational field of the deflector. This image distortion can be quite weak and can then not be detected in individual images. However, since we are lucky to live in a Universe where the sky is full of faint distant galaxies, this distortion effect can be discovered statistically. This immediately implies that weak lensing requires excellent and deep images so that image shapes (and sizes) can be accurately measured and the number density be as high as possible to reduce statistical uncertainties. Weak gravitational lensing can be defined as using the faint galaxy population to measure the mass and/or mass distribution of individual intervening cosmic structures, or the statistical properties of their mass distribution, or to detect them in the first place, independent of the physical state or nature of the matter, or the luminosity of these mass concentrations. In addition, weak lensing can be used to infer the redshift distribution of the faintest galaxies. After introducing the necessary concepts, I will list the main applications of weak lensing and discuss some of them in slightly more detail, stressing the need for very deep and wide-field images of the sky taken with instruments of excellent image quality.

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