KERR BLACK HOLE GRAVITATIONAL LENSING IN THE STRONG DEFLECTION LIMIT: AN ANALYTICAL APPROACH

2008 ◽  
Author(s):  
FABIANA De LUCA
Keyword(s):  
Black Hole ◽  
Gravitational Lensing ◽  
Analytical Approach ◽  
Kerr Black Hole ◽  
Deflection Limit

scholarly journals Exploring higher order images with Fe Kα-lines from relativistic disks: black hole spin determination and bias

2021 ◽  
Author(s):  
M Falanga ◽  
P Bakala ◽  
R La Placa ◽  
V De Falco ◽  
A De Rosa ◽  
...  
Keyword(s):  
Black Hole ◽  
Line Profile ◽  
Gravitational Lensing ◽  
Kerr Black Hole ◽  
Higher Order ◽  
Large Area ◽  
X Ray ◽  
Area Detector ◽  
Black Hole Spin ◽  
Stable Circular Orbit

Abstract We study the contributions to the relativistic Fe Kα line profile from higher order images (HOIs) produced by strongly deflected rays from the disk which cross the plunging region, located between the innermost stable circular orbit (ISCO) radius and the event horizon of a Kerr black hole. We investigate the characteristics features imprinted by the HOIs in the line profile for different black hole spins, disk emissivity laws and inclinations. We find that they extend from the red wing of the profile up to energies slightly lower than those of the blue peak, adding ∼0.4 − 1.3 per cent to the total line flux. The contribution to the specific flux is often in the ∼1 per cent to 7 per cent range, with the highest values attained for low and negative spin (a ≲ 0.3) black holes surrounded by intermediate inclination angle (i ∼ 40○) disks. We simulate future observations of a black hole X-ray binary system with the Large Area Detector of the planned X-ray astronomy enhanced X-ray Timing and Polarimetry Mission (eXTP) and find that the Fe Kα line profiles of systems accreting at ≲ 1 per cent the Eddington rate are affected by the HOI features for a range of parameters. This would provide evidence of the extreme gravitational lensing of HOI rays. Our simulations show also that not accounting for HOI contributions to the Fe Kα line profile may systematically bias measurements of the black hole spin parameter towards values higher by up to ∼0.3 than the inputted ones.

Strong gravitational lensing by Kerr–Newman-Nut-Quintessence black hole

2021 ◽  
Author(s):  
Niyaz Uddin Molla ◽  
Ujjal Debnath
Keyword(s):  
Black Hole ◽  
Equatorial Plane ◽  
Gravitational Lensing ◽  
Deflection Angle ◽  
Null Geodesic ◽  
Kerr Black Hole ◽  
Eos Parameter ◽  
Strong Gravitational Lensing ◽  
Spin Parameter ◽  
The Deflection Angle

We investigate the strong gravitational lensing on equatorial plane as well as quasi-equatorial plane by the Kerr–Newman-Nut-Quintessence (KNNQ) black hole (BH) with the equation of state (EoS) parameter of the quintessence [Formula: see text] and the quintessence density [Formula: see text]. Our results show that the strong gravitational lensing in the KNNQ black hole space–time has some distinct behaviors from those in the backgrounds of the four dimension Kerr black hole. Also, we investigate the strong gravitational lensing on equatorial plane as well as quasi-equatorial plane by the KNNQ BH with the effects of Nut charge, spin parameter and quintessence parameter. First, we calculate the null geodesic equations using the Hamilton–Jacobi separation method. Then we investigate the equatorial lensing by KNNQ black hole. We obtain the deflection angle and deflection coefficients in the equatorial plane, which is affected by EoS parameter of the quintessence [Formula: see text], quintessence density [Formula: see text], Nut parameter [Formula: see text], spin parameter [Formula: see text] and quintessence parameter [Formula: see text] [Formula: see text]. Next, we discuss the lens equation and the observables in the equatorial plane. Finally, we investigate gravitational lensing by the KNNQ black hole in the quasi-equatorial plane. In this work, the quintessence density [Formula: see text], the EoS parameter of the quintessence [Formula: see text], Nut parameter [Formula: see text], spin parameter [Formula: see text] and quintessence parameter [Formula: see text] [Formula: see text] have significant effects on the strong gravitational lensing both in equatorial plane as well as quasi-equatorial plane.

scholarly journals Strong lensing and observables around 5D Myers–Perry black hole spacetime

2018 ◽  
Vol 33 (23) ◽  
pp. 1850126
Author(s):  
Ravi Shankar Kuniyal ◽  
Hemwati Nandan ◽  
Uma Papnoi ◽  
Rashmi Uniyal ◽  
K. D. Purohit
Keyword(s):  
Black Hole ◽  
Deflection Angle ◽  
Strong Field ◽  
Kerr Black Hole ◽  
Four Dimensions ◽  
Test Particles ◽  
Spin Parameter ◽  
Black Hole Spacetime ◽  
Field Coefficient ◽  
Deflection Limit

We study the motion of massless test particles in a five-dimensional (5D) Myers–Perry black hole spacetime with two-spin parameters. The behavior of the effective potential in view of different values of black hole parameters is discussed in the equatorial plane. The frequency shift of photons is calculated which is found to depend on the spin parameter of black hole and the observed redshift is discussed accordingly. The deflection angle and the strong deflection limit coefficients are also calculated and their behavior with the spin parameters is analyzed in detail. It is observed that the behaviors of both deflection angle and strong field coefficient differs from Kerr black hole spacetime in four dimensions in General Relativity (GR), which is mainly due to the presence of two-spin parameters in higher dimension.

scholarly journals Null Geodesics and Gravitational Lensing in a Nonsingular Spacetime

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Shao-Wen Wei ◽  
Yu-Xiao Liu ◽  
Chun-E Fu
Keyword(s):  
Black Hole ◽  
Gravitational Lensing ◽  
Angular Position ◽  
Angular Separation ◽  
Null Geodesics ◽  
Astronomical Instruments ◽  
Black Hole Background ◽  
Deflection Limit ◽  
Near Future

The null geodesics and gravitational lensing in a nonsingular spacetime are investigated. According to the nature of the null geodesics, the spacetime is divided into several cases. In the weak deflection limit, we find the influence of the nonsingularity parameterqon the positions and magnifications of the images is negligible. In the strong deflection limit, the coefficients and observables for the gravitational lensing in a nonsingular black hole background and a weakly nonsingular spacetime are obtained. Comparing these results, we find that, in a weakly nonsingular spacetime, the relativistic images have smaller angular position and relative magnification but larger angular separation than those of a nonsingular black hole. These results might offer a way to probe the spacetime nonsingularity parameter and put a bound on it by the astronomical instruments in the near future.

Gravitational Lensing by Kerr-Sen Dilaton-Axion Black Hole in the Weak Deflection Limit

2010 ◽  
Author(s):  
G. N. Gyulchev ◽  
S. S. Yazadjiev ◽  
Michail D. Todorov ◽  
Christo I. Christov
Keyword(s):  
Black Hole ◽  
Gravitational Lensing ◽  
Deflection Limit
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