scholarly journals Twisted light, a new tool for general relativity and beyond — Revealing the properties of rotating black holes with the vorticity of light —

Author(s):  
F. Tamburini ◽  
F. Feleppa ◽  
B. Thidé

We describe and present the first observational evidence that light propagating near a rotating black hole is twisted in phase and carries orbital angular momentum. The novel use of this physical observable as an additional tool for the previously known techniques of gravitational lensing allows us to directly measure, for the first time, the spin parameter of a black hole. With the additional information encoded in the orbital angular momentum, not only can we reveal the actual rotation of the compact object, but we can also use rotating black holes as probes to test general relativity.

2007 ◽  
Vol 22 (26) ◽  
pp. 4849-4858 ◽  
Author(s):  
A. SHEYKHI ◽  
N. RIAZI

We consider charged black holes with curved horizons, in five-dimensional dilaton gravity in the presence of Liouville-type potential for the dilaton field. We show how, by solving a pair of coupled differential equations, infinitesimally small angular momentum can be added to these static solutions to obtain charged rotating dilaton black hole solutions. In the absence of dilaton field, the nonrotating version of the solution reduces to the five-dimensional Reissner–Nordström black hole, and the rotating version reproduces the five-dimensional Kerr–Newman modification thereof for small rotation parameter. We also compute the angular momentum and the angular velocity of these rotating black holes which appear at the first order.


2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
S. H. Hendi ◽  
M. Allahverdizadeh

We study charged slowly rotating black hole with a nonlinear electrodynamics (NED) in the presence of cosmological constant. Starting from the static solutions of Einstein-NED gravity as seed solutions, we use the angular momentum as the perturbative parameter to obtain slowly rotating black holes. We perform the perturbations up to the linear order for black holes in 4 dimensions. These solutions are asymptotically AdS and their horizon has spherical topology. We calculate the physical properties of these black holes and study their dependence on the rotation parameteraas well as the nonlinearity parameterβ. In the limitβ→∞, the solution describes slowly rotating AdS type black holes.


2020 ◽  
Author(s):  
Deep Bhattacharjee

This paper is totally based on the mathematical physics of the Black holes. In Einstein’s theory of “General Relativity”, Schwarzschild solution is the vacuum solutions of the Einstein Field Equations that describes the gravity potential from outside the body of a spherically symmetric object having zero charge, zero mass and zero cosmological constant[1]. It was discovered by Karl Schwarzschild in 1916, a little more than a month after the publication of the famous GR and the singularity is a point singularity which can be best described as a coordinate singularity rather than a real singularity, however, the drawback of this theory is that it fails to take into account the real life scenario of black holes with charge and spin angular momentum. The black hole is based on event horizon and Schwarzschild radius. However, Physicists were trying to develop a metric for the real life scenario of a black hole with a spin angular momen-tum and ultimately the exact solution of a charged rotating black hole had been discovered by Roy Kerr in 1965 as the Kerr-Newman metric[2][3]. The Kerr metric is one of the toughest metric in physics and is the extensional generalization to a rotating body of the Schwarzschild metric. The metric describes the vacuum geometry of space-time around a rotating axially-symmetric black hole with a quasipotential event horizon. In Kerr metric there are two event hori-zons (inner and outer), two ergospheres and an ergosurface. The most important effect of the Kerr metric is the frame dragging (also known as Lense-Thirring Precession) is a distinctive prediction of General relativity. The first direct observation of the collision of two Kerr Black Holes has been discovered by LIGO in 2016 hence setting up a milestone of General Relativity in the history of Physics. Here, the Kerr metric has been introduced in the Boyer-Lindquist forms and it is derived from the Schwarzschild metric using the Spin-Coefficient formalism. According to the “Cosmic Censorship Hypothesis”, a naked singularity cannot exist in nature as nature always hides the singularity via an event horizon. However, in this paper I will prove the existence of the “Naked Singularity" taking the advantage of the Ring Singularity of the Kerr Black Hole and thereby making the way to manipulate the mathematics by taking the larger root of Δ as zero and thereby vanishing the ergosphere and event horizon making the way for the naked ring singularity which can be easily connected via a cylindrical wormhole and as ‘a wormhole is a black hole without an event horizon’ therefore, this cylindrical connection paved the way for the Einstein-Rosen Bridge allowing particles or null rays to travel from one universe to another ending up in a future directed Cauchy horizon while changing constantly from spatial to temporal and again spatial paving the entrance to another Kerr Black hole (which would act as a white hole) in the other universes. I will not go in detail about the contradiction of ‘Chronology Protection Conjecture” [4]whether the Stress-Energy-Momentum Tensor can violate the ANEC (Average Null Energy Conditions) or not with the values of less than zero or greater than, equal to zero, instead I will focus definitely on the creation of the mathematical formulation of a wormhole from a Naked Ring Kerr Singularity of a Kerr Black Hole without any event horizon or ergosphere. Another important thing to mention in this paper is that I have taken the time to be imaginary[5] as because, a singularity being an eternal point of time can only be smoothen out if the time is imaginary rather than real which will allow the particle or null rays inside a wormhole to cross the singularity and making entrance to the other universe. The final conclusion would be to determine the mass-energy equivalence principle as spin angular momentum increases with a decrease in BH mass due to the vanishing event horizon and ergosphere thereby maintaining the equivalence via apparent and absolute masses in relation to spin J along the orthogonal Z axis. A ‘NAKED SINGULARITY’ alters every parameters of a BH and to include this parameters along with affine spin coefficient, it has been proved that without any spin angular momentum the generation of wormhole and vanishing of event horizon and singularity is not possible.


2012 ◽  
Vol 21 (08) ◽  
pp. 1250068 ◽  
Author(s):  
ALEXIS LARRAÑAGA

In this paper, we analyze the area spectrum of BTZ three-dimensional black holes by considering an outgoing wave and relating its period of motion with the period of the gravitational system with respect to Euclidean time. The area spectra obtained for the rotating and non-rotating black holes are equally spaced and it is important to note that in this paper, we do not need to use the small angular momentum assumption which is necessary in the quasinormal mode approach for rotating black holes. The results suggest that the periodicity of the black hole gravitational system may be the origin of area quantization.


Entropy ◽  
2019 ◽  
Vol 21 (10) ◽  
pp. 1017
Author(s):  
Bogeun Gwak

We investigate the energy of the gravitational wave from a binary black hole merger by the coalescence of two Kerr black holes with an orbital angular momentum. The coalescence is constructed to be consistent with particle absorption in the limit in which the primary black hole is sufficiently large compared with the secondary black hole. In this limit, we analytically obtain an effective gravitational spin–orbit interaction dependent on the alignments of the angular momenta. Then, binary systems with various parameters including equal masses are numerically analyzed. According to the numerical analysis, the energy of the gravitational wave still depends on the effective interactions, as expected from the analytical form. In particular, we ensure that the final black hole obtains a large portion of its spin angular momentum from the orbital angular momentum of the initial binary black hole. To estimate the angular momentum released by the gravitational wave in the actual binary black hole, we apply our results to observations at the Laser Interferometer Gravitational-Wave Observatory: GW150914, GW151226, GW170104, GW170608 and GW170814.


2007 ◽  
Vol 3 (S248) ◽  
pp. 498-499
Author(s):  
W. B. Han

AbstractIn general, the model of galaxy assumes a central huge black hole surrounded by a massive halo, disk or ring. In this paper, we investigate the gravitational field structure of a slowly rotating black hole with a dipolar halo, and the dynamics and chaos of test particles moving in it. Using Poincaré sections and fast Lyapunov indicator (FLI) in general relativity, we investigate chaos under different dynamical parameters, and find that the FLI is suitable for detecting chaos and even resonant orbits.


1998 ◽  
Vol 07 (03) ◽  
pp. 471-488 ◽  
Author(s):  
T. LØVÅS

The use of modified Newtonian potentials to describe the gravitational field around black holes has proven successful. I will present here an investigation of the accuracy of several modified Newtonian potentials proposed in the literature, by comparing the result with the exact relativistic solution. I will do so for optically thin accretion disks that are more sensitive to the form of the potential than optically thick standard disks. I find that simple modified Newtonian potentials capture the essential features of general relativity, and the results from using the modified Newtonian potentials deviate from the relativistic result only by 20% at most for nonrotating black holes. For rotating black holes the accuracy depends on the rotation of the black hole.


2016 ◽  
Vol 25 (07) ◽  
pp. 1650079 ◽  
Author(s):  
Gamal G. L. Nashed

We derive set of solutions with flat transverse sections in the framework of a teleparallel equivalent of general relativity which describes rotating black holes. The singularities supported from the invariants of torsion and curvature are explained. We investigate that there appear more singularities in the torsion scalars than in the curvature ones. The conserved quantities are discussed using Einstein–Cartan geometry. The physics of the constants of integration is explained through the calculations of conserved quantities. These calculations show that there is a unique solution that may describe true physical black hole.


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