scholarly journals Bending angle of light in equatorial plane of Kerr–Sen Black Hole

2018 ◽  
Vol 782 ◽  
pp. 185-192 ◽  
Author(s):  
Rashmi Uniyal ◽  
Hemwati Nandan ◽  
Philippe Jetzer
Keyword(s):  
Black Hole ◽  
Equatorial Plane ◽  
Bending Angle

On embeddings of the Kerr geometry

1981 ◽  
Vol 59 (5) ◽  
pp. 688-692 ◽  
Author(s):  
Nigel A. Sharp
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Equatorial Plane ◽  
Kerr Metric ◽  
Intrinsic Structure ◽  
Kerr Geometry ◽  
Rotating Black Hole ◽  
Isometric Embeddings

The use of isometric embeddings of curved geometries reveals their intrinsic structure in a way that is readily appreciated. This is done for 3 two-surfaces sliced from the Kerr metric which describes a rotating black hole: the equatorial plane, the event horizon, and the ergosurface.

scholarly journals Tidal disruption event discs around supermassive black holes: disc warp and inclination evolution

2019 ◽  
Vol 487 (4) ◽  
pp. 4965-4984 ◽  
Author(s):  
J J Zanazzi ◽  
Dong Lai
Keyword(s):  
Black Hole ◽  
Equatorial Plane ◽  
Accretion Rate ◽  
Accretion Disc ◽  
Precession Frequency ◽  
Tidal Disruption ◽  
Eigenmode Analysis ◽  
Accretion Rates ◽  
Rigid Disc ◽  
Disruption Event

ABSTRACT After the tidal disruption event (TDE) of a star around a supermassive black hole (SMBH), the bound stellar debris rapidly forms an accretion disc. If the accretion disc is not aligned with the spinning SMBH’s equatorial plane, the disc will be driven into Lense–Thirring precession around the SMBH’s spin axis, possibly affecting the TDE’s light curve. We carry out an eigenmode analysis of such a disc to understand how the disc’s warp structure, precession, and inclination evolution are influenced by the disc’s and SMBH’s properties. We find an oscillatory warp may develop as a result of strong non-Keplarian motion near the SMBH. The global disc precession frequency matches the Lense–Thirring precession frequency of a rigid disc around a spinning black hole within a factor of a few when the disc’s accretion rate is high, but deviates significantly at low accretion rates. Viscosity aligns the disc with the SMBH’s equatorial plane over time-scales of days to years, depending on the disc’s accretion rate, viscosity, and SMBH’s mass. We also examine the effect of fallback material on the warp evolution of TDE discs, and find that the fallback torque aligns the TDE disc with the SMBH’s equatorial plane in a few to tens of days for the parameter space investigated. Our results place constraints on models of TDE emission which rely on the changing disc orientation with respect to the line of sight to explain observations.

LOOP VARIABLE AND HOLONOMY TRANSFORMATIONS IN THE KERR–NEWMAN SPACE–TIME

2007 ◽  
Vol 16 (08) ◽  
pp. 1327-1339
Author(s):  
J. GOMES DE ASSIS ◽  
C. FURTADO ◽  
V. B. BEZERRA
Keyword(s):  
Black Hole ◽  
Equatorial Plane ◽  
Space Time ◽  
Charged Black Hole

We compute the loop variable for different curves in the Kerr–Newman space–time, taking into account the appropriate modification of these quantities due to the rotation of the source. In parallel transporting of both vectors and spinors, we examine how the rotation of the charged black hole affects the holonomy for a circle on the equatorial plane.

scholarly journals Global embeddings and hydrodynamic properties of Kerr black hole

2016 ◽  
Vol 31 (35) ◽  
pp. 1650204
Author(s):  
Soon-Tae Hong
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Equatorial Plane ◽  
Kerr Black Hole ◽  
Kerr Spacetime ◽  
Stable Circular Orbit ◽  
Massive Particles ◽  
Flat Embedding ◽  
Bound Orbits ◽  
The Impact

In the presence of a rotating Kerr black hole, we investigate hydrodynamics of the massive particles and massless photons to construct relations among number density, pressure and internal energy density of the massive particles and photons around the rotating Kerr black hole and to study an accretion onto the black hole. On equatorial plane of the Kerr black hole, we investigate the bound orbits of the massive particles and photons around the black hole to produce their radial, azimuthal and precession frequencies. With these frequencies, we study the black holes GRO J1655-40 and 4U 1543-47 to explicitly obtain the radial, azimuthal and precession frequencies of the massive particles in the flow of perfect fluid. We next consider the massive particles in the stable circular orbit of radius of 1.0 ly around the supernovas SN 1979C, SN 1987A and SN 2213-1745 in the Kerr curved spacetime, and around the potential supermassive Schwarzschild black holes M87, NGC 3115, NGC 4594, NGC 3377, NGC 4258, M31, M32 and Galatic center, to estimate their radial and azimuthal frequencies, which are shown to be the same results as those in no precession motion. The photon unstable orbit is also discussed in terms of the impact parameter of the photon trajectory. Finally, on the equatorial plane of the Kerr black hole, we construct the global flat embedding structures possessing (9 + 3) dimensionalities outside and inside the event horizon of the rotating Kerr black hole. Moreover, on the plane, we investigate the warp products of the Kerr spacetime.

Trajectories of material particles in Kerr–Newman–de Sitter space–time

1989 ◽  
Vol 67 (5) ◽  
pp. 501-504
Author(s):  
K. D. Krori ◽  
Ranjana Choudhury ◽  
J. C. Sarmah
Keyword(s):  
Black Hole ◽  
Equatorial Plane ◽  
De Sitter Space ◽  
Space Time ◽  
De Sitter ◽  
Newman Black Hole

In this paper we show that in the Kerr–Newman–de Sitter space–time material particles may move in stable orbits in the equatorial plane (θ = π/2) of the Kerr–Newman black hole.

scholarly journals Deflection of light around a rotating BTZ black hole

2020 ◽  
Vol 35 (39) ◽  
pp. 2050323
Author(s):  
Shubham Kala ◽  
Hemwati Nandan ◽  
Prateek Sharma
Keyword(s):  
Black Hole ◽  
Cosmological Constant ◽  
Test Particle ◽  
Gravitational Lensing ◽  
Critical Parameters ◽  
Btz Black Hole ◽  
Bending Angle ◽  
Retrograde Motion ◽  
Test Particles ◽  
Dimensional Gravity

We present a detailed study of gravitational lensing around a rotating Bañados–Teitelboim–Zanelli (BTZ) black hole in (2 + 1)-dimensional gravity. The study of orbits for massless test particle around this BH spacetime is performed to describe the nature of cosmological constant in lower dimensions. We study the effect of cosmological constant on the photon orbit in view of other critical parameters. The bending angle of light is studied in view of different values of cosmological constant for direct and retrograde motion of test particles. It is being observed that the bending angle slightly decreases as the value of cosmological constant increases in the negative region.

Effects of the external magnetic field on the Lense–Thirring precession

2021 ◽  
Author(s):  
Muhammad Rizwan ◽  
Tooba Feroze
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
External Magnetic Field ◽  
Equatorial Plane ◽  
Polar Axis ◽  
Precession Frequency ◽  
Black Hole Spacetime ◽  
Newman Black Hole

In this paper, we study the effects of the external magnetic field on the Lense–Thirring (LT) precession of a test gyroscope attached to an observer in magnetized black hole spacetime. For this, we consider a Kerr–Newman black hole embedded in the external magnetic field. The LT precession of a test gyroscope diverges near the ergosurface and remains finite everywhere outside the ergosurface. It is seen that by increasing the external magnetic field, the LT precession frequency in the region of large [Formula: see text] decreases as [Formula: see text] increases, while the precession frequency in the region of small [Formula: see text] increases as [Formula: see text] increases, whereas it increases with increasing the charge of the black hole. The LT precession of a test gyroscope attached to observers moving along the directions close to the polar axis is greater than that of the observer moving in the equatorial plane.

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