Measurement of the spin of the M87 black hole from its observed twisted light

ABSTRACT We present the first observational evidence that light propagating near a rotating black hole is twisted in phase and carries orbital angular momentum (OAM). This physical observable allows a direct measurement of the rotation of the black hole. We extracted the OAM spectra from the radio intensity data collected by the Event Horizon Telescope from around the black hole M87* by using wavefront reconstruction and phase recovery techniques and from the visibility amplitude and phase maps. This method is robust and complementary to black hole shadow circularity analyses. It shows that the M87* rotates clockwise with an estimated rotation parameter a = 0.90 ± 0.05 with an $\sim 95{{\ \rm per\ cent}}$ confidence level (c.l.) and an inclination i = 17° ± 2°, equivalent to a magnetic arrested disc with an inclination i = 163° ± 2°. From our analysis, we conclude that, within a 6σ c.l., the M87* is rotating.

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Slowly Rotating Black Holes with Nonlinear Electrodynamics

Advances in High Energy Physics ◽

10.1155/2014/390101 ◽

2014 ◽

Vol 2014 ◽

pp. 1-7 ◽

Cited By ~ 8

Author(s):

S. H. Hendi ◽

M. Allahverdizadeh

Keyword(s):

Black Holes ◽

Black Hole ◽

Angular Momentum ◽

Linear Order ◽

Rotation Parameter ◽

Nonlinear Electrodynamics ◽

Nonlinearity Parameter ◽

Static Solutions ◽

Rotating Black Holes ◽

Spherical Topology

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.

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

International Journal of Modern Physics D ◽

10.1142/s0218271821420177 ◽

2021 ◽

Author(s):

F. Tamburini ◽

F. Feleppa ◽

B. Thidé

Keyword(s):

Black Holes ◽

General Relativity ◽

Black Hole ◽

Angular Momentum ◽

Orbital Angular Momentum ◽

Gravitational Lensing ◽

Compact Object ◽

Additional Tool ◽

Physical Observable ◽

Rotating Black Holes

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.

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Photon boomerang in a nearly extreme Kerr metric

Classical and Quantum Gravity ◽

10.1088/1361-6382/ac36e5 ◽

2021 ◽

Author(s):

Don N Page

Keyword(s):

Black Hole ◽

Angular Momentum ◽

Opposite Direction ◽

Elliptic Integral ◽

Polar Axis ◽

Rotation Parameter ◽

Kerr Metric ◽

Complete Elliptic Integral ◽

The North ◽

North Polar

Abstract The Kerr rotating black hole metric has unstable photon orbits that orbit around the hole at ﬁxed values of the Boyer-Lindquist coordinate r that depend on the axial angular momentum of the orbit, as well as on the parameters of the hole. For zero orbital axial angular momentum, these orbits cross the rotational axes at a ﬁxed value of r that depends on the mass M and angular momentum J of the black hole. Nonzero angular momentum of the hole causes the photon orbit to rotate so that its direction when crossing the north polar axis changes from one crossing to the next by an angle I shall call ∆φ, which depends on the black hole dimensionless rotation parameter a/M = cJ/(GM2) by an equation involving a complete elliptic integral of the ﬁrst kind. When the black hole has a/M ≈ 0.994 341 179 923 26, which is nearly maximally rotating, a photon sent out in a constant-r direction from the north polar axis at r ≈ 2.423 776 210 035 73 GM/c2returns to the north polar axis in precisely the opposite direction (in a frame nonrotating with respect to the distant stars), a photon boomerang.

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Infrared effects in the late stages of black hole evaporation

Journal of High Energy Physics ◽

10.1007/jhep07(2021)137 ◽

2021 ◽

Vol 2021 (7) ◽

Author(s):

Éanna É. Flanagan

Keyword(s):

Black Hole ◽

Angular Momentum ◽

Center Of Mass ◽

Planck Scale ◽

Black Hole Mass ◽

Order Unity ◽

Intrinsic Angular Momentum ◽

Hole Position ◽

Late Stages ◽

Shear Tensor

Abstract As a black hole evaporates, each outgoing Hawking quantum carries away some of the black holes asymptotic charges associated with the extended Bondi-Metzner-Sachs group. These include the Poincaré charges of energy, linear momentum, intrinsic angular momentum, and orbital angular momentum or center-of-mass charge, as well as extensions of these quantities associated with supertranslations and super-Lorentz transformations, namely supermomentum, superspin and super center-of-mass charges (also known as soft hair). Since each emitted quantum has fluctuations that are of order unity, fluctuations in the black hole’s charges grow over the course of the evaporation. We estimate the scale of these fluctuations using a simple model. The results are, in Planck units: (i) The black hole position has a uncertainty of $$ \sim {M}_i^2 $$ ∼ M i 2 at late times, where Mi is the initial mass (previously found by Page). (ii) The black hole mass M has an uncertainty of order the mass M itself at the epoch when M ∼ $$ {M}_i^{2/3} $$ M i 2 / 3 , well before the Planck scale is reached. Correspondingly, the time at which the evaporation ends has an uncertainty of order $$ \sim {M}_i^2 $$ ∼ M i 2 . (iii) The supermomentum and superspin charges are not independent but are determined from the Poincaré charges and the super center-of-mass charges. (iv) The supertranslation that characterizes the super center-of-mass charges has fluctuations at multipole orders l of order unity that are of order unity in Planck units. At large l, there is a power law spectrum of fluctuations that extends up to l ∼ $$ {M}_i^2/M $$ M i 2 / M , beyond which the fluctuations fall off exponentially, with corresponding total rms shear tensor fluctuations ∼ MiM−3/2.

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Gaseous Disks in the Nuclei of Elliptical Galaxies

International Astronomical Union Colloquium ◽

10.1017/s0252921100043293 ◽

1997 ◽

Vol 163 ◽

pp. 620-625 ◽

Cited By ~ 4

Author(s):

H. Ford ◽

Z. Tsvetanov ◽

L. Ferrarese ◽

G. Kriss ◽

W. Jaffe ◽

...

Keyword(s):

Black Holes ◽

Black Hole ◽

Angular Momentum ◽

Accretion Disks ◽

Large Scale ◽

Elliptical Galaxies ◽

Central Mass ◽

Massive Black Holes ◽

Radio Jets

AbstractHST images have led to the discovery that small (r ~ 1″ r ~ 100 – 200 pc), well-defined, gaseous disks are common in the nuclei of elliptical galaxies. Measurements of rotational velocities in the disks provide a means to measure the central mass and search for massive black holes in the parent galaxies. The minor axes of these disks are closely aligned with the directions of the large–scale radio jets, suggesting that it is angular momentum of the disk rather than that of the black hole that determines the direction of the radio jets. Because the disks are directly observable, we can study the disks themselves, and investigate important questions which cannot be directly addressed with observations of the smaller and unresolved central accretion disks. In this paper we summarize what has been learned to date in this rapidly unfolding new field.

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Circum-nuclear molecular disks: Role in AGN fueling and feedback

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320001544 ◽

2019 ◽

Vol 15 (S359) ◽

pp. 312-317

Author(s):

Francoise Combes

Keyword(s):

Black Hole ◽

Angular Momentum ◽

High Resolution ◽

Large Scale ◽

Active Galaxy ◽

Small Scale ◽

Massive Black Hole ◽

Molecular Outflows ◽

Molecular Outflow

AbstractGas fueling AGN (Active Galaxy Nuclei) is now traceable at high-resolution with ALMA (Atacama Large Millimeter Array) and NOEMA (NOrthern Extended Millimeter Array). Dynamical mechanisms are essential to exchange angular momentum and drive the gas to the super-massive black hole. While at 100pc scale, the gas is sometimes stalled in nuclear rings, recent observations reaching 10pc scale (50mas), may bring smoking gun evidence of fueling, within a randomly oriented nuclear gas disk. AGN feedback is also observed, in the form of narrow and collimated molecular outflows, which point towards the radio mode, or entrainment by a radio jet. Precession has been observed in a molecular outflow, indicating the precession of the radio jet. One of the best candidates for precession is the Bardeen-Petterson effect at small scale, which exerts a torque on the accreting material, and produces an extended disk warp. The misalignment between the inner and large-scale disk, enhances the coupling of the AGN feedback, since the jet sweeps a large part of the molecular disk.

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Simulations of disks in binary systems using parallelized SPH to reach extreme spatial resolution

Symposium - International Astronomical Union ◽

10.1017/s0074180900207596 ◽

2003 ◽

Vol 208 ◽

pp. 427-428

Author(s):

D. Molteni ◽

F. Fauci ◽

G. Gerardi ◽

M. A. Valenza

Keyword(s):

Black Hole ◽

Angular Momentum ◽

Numerical Simulations ◽

Spatial Resolution ◽

Spectral Properties ◽

Binary Systems ◽

Compact Star ◽

Close Binary ◽

Gas Transfer ◽

Set Up

Results of 3D numerical simulations of the gas transfer in close binary systems show that it is possible the production of accretion streams having low specific angular momentum in a region close to the accreting star. These streams are mainly placed above the orbital disc. The eventual formation of such bulges and shock heated flows is interesting in the context of advection dominated solutions and for the explanation of spectral properties of the Black Hole candidates in binary systems. We set up a parallelized version of 3D S.P.H. code, using domain decomposion. with increasing spatial resolution around the compact star.

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