Special Issue "Black Hole Physics and Astrophysics"

A special issue of Universe (ISSN 2218-1997).

Deadline for manuscript submissions: 29 February 2020.

Special Issue Editor

Prof. Dr. Vyacheslav Ivanovich Dokuchaev
E-Mail Website
Guest Editor
Institute for Nuclear Research of the Russian Academy of Sciences, Moscow 117312, Russia
Interests: black holes; cosmology; theory of gravity; physics of the early universe

Special Issue Information

Dear Colleagues,

Nowadays the technological achievements in astrophysical observations earnestly demonstrate that black holes are the most important objects in the universe. Comprehensive observational and theoretical investigations are urgently requested for better understanding of black hole physics, as the outside and also inside of the black hole event horizon.

Reviews and papers with fresh data and ideas are especially welcome.

Prof. Dr. Vyacheslav Ivanovich Dokuchaev
Guest Editor

Manuscript Submission Information

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Keywords

  • Black holes
  • Primordial black holes
  • Cosmological black holes
  • Black hole interiors
  • Dark energy around black holes
  • Dark matter around black holes
  • Physics of the early universe
  • Theory of gravity
  • Einstein gravity
  • Black holes in modified gravity
  • Spacetime singularities
  • Astroparticle physics
  • Relativistic accretion
  • Gravitational waves

Published Papers (4 papers)

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Research

Open AccessArticle
Static State of a Black Hole Supported by Dark Matter
Universe 2019, 5(9), 198; https://doi.org/10.3390/universe5090198 - 13 Sep 2019
Abstract
The possibility of an equilibrium state of a gravitating scalar field (describing ordinary matter) inside a black hole, compressed to the state of boson condensate, in balance with a longitudinal vector field (describing dark matter) from the outside, is considered. Analytical analysis, confirmed [...] Read more.
The possibility of an equilibrium state of a gravitating scalar field (describing ordinary matter) inside a black hole, compressed to the state of boson condensate, in balance with a longitudinal vector field (describing dark matter) from the outside, is considered. Analytical analysis, confirmed numerically, shows that there are regular static solutions to the Einstein equations with no limitation on the mass of a black hole. The metric tensor component grr(r) changes sign twice. The behavior of the gravitational field and material fields in the vicinity of these two Schwarzschild radii were studied in detail. The equality of the energy–momentum tensors of the scalar and longitudinal vector fields at the interface supports the phase equilibrium of a black hole and dark matter. Considering the gravitating scalar field as an example, a possible internal structure of a black hole and its influence on the dark matter at the periphery of a galaxy are clarified. In particular, the speed on the plateau of a galaxy rotation curve as a function of a black hole’s mass is determined. Full article
(This article belongs to the Special Issue Black Hole Physics and Astrophysics)
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Open AccessArticle
Hot Accretion Flow in Two-Dimensional Spherical Coordinates: Considering Pressure Anisotropy and Magnetic Field
Universe 2019, 5(9), 197; https://doi.org/10.3390/universe5090197 - 12 Sep 2019
Abstract
For systems with extremely low accretion rate, such as Galactic Center Sgr A* and M87 galaxy, the ion collisional mean free path can be considerably larger than its Larmor radius. In this case, the gas pressure is anisotropic to magnetic field lines. In [...] Read more.
For systems with extremely low accretion rate, such as Galactic Center Sgr A* and M87 galaxy, the ion collisional mean free path can be considerably larger than its Larmor radius. In this case, the gas pressure is anisotropic to magnetic field lines. In this paper, we pay attention to how the properties of outflow change with the strength of anisotropic pressure and the magnetic field. We use an anisotropic viscosity to model the anisotropic pressure. We solve the two-dimensional magnetohydrodynamic (MHD) equations in spherical coordinates and assume that the accretion flow is radially self-similar. We find that the work done by anisotropic pressure can heat the accretion flow. The gas temperature is heightened when anisotropic stress is included. The outflow velocity increases with the enhancement of strength of the anisotropic force. The Bernoulli parameter does not change much when anisotropic pressure is involved. However, we find that the energy flux of outflow can be increased by a factor of 20 in the presence of anisotropic stress. We find strong wind (the mass outflow is about 70% of the mass inflow rate) is formed when a relatively strong magnetic field is present. Outflows from an active galactic nucleus can interact with gas in its host galaxies. Our result predicts that outflow feedback effects can be enhanced significantly when anisotropic pressure and a relatively powerful magnetic field is considered. Full article
(This article belongs to the Special Issue Black Hole Physics and Astrophysics)
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Open AccessArticle
The Brightest Point in Accretion Disk and Black Hole Spin: Implication to the Image of Black Hole M87*
Universe 2019, 5(8), 183; https://doi.org/10.3390/universe5080183 - 05 Aug 2019
Cited by 3
Abstract
We propose the simple new method for extracting the value of the black hole spin from the direct high-resolution image of black hole by using a thin accretion disk model. In this model, the observed dark region on the first image of the [...] Read more.
We propose the simple new method for extracting the value of the black hole spin from the direct high-resolution image of black hole by using a thin accretion disk model. In this model, the observed dark region on the first image of the supermassive black hole in the galaxy M87, obtained by the Event Horizon Telescope, is a silhouette of the black hole event horizon. The outline of this silhouette is the equator of the event horizon sphere. The dark silhouette of the black hole event horizon is placed within the expected position of the black hole shadow, which is not revealed on the first image. We calculated numerically the relation between the observed position of the black hole silhouette and the brightest point in the thin accretion disk, depending on the black hole spin. From this relation, we derive the spin of the supermassive black hole M87*, a = 0.75 ± 0.15 . Full article
(This article belongs to the Special Issue Black Hole Physics and Astrophysics)
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Open AccessArticle
Quantum Complexity and Chaos in Young Black Holes
Universe 2019, 5(4), 93; https://doi.org/10.3390/universe5040093 - 22 Apr 2019
Cited by 1
Abstract
We argue that the problem of calculating retention time scales in young black holes is a problem of relative state complexity. In particular, we suggest that Alice’s ability to estimate the time scale for a perturbed black hole to release the extra n [...] Read more.
We argue that the problem of calculating retention time scales in young black holes is a problem of relative state complexity. In particular, we suggest that Alice’s ability to estimate the time scale for a perturbed black hole to release the extra n qubits comes down to her decoding the Hilbert space of the Hawking radiation. We then demonstrate the decoding task Alice faces is very difficult, and in order to calculate the relative state complexity she would either need to act with an exponentially complex unitary operator or apply an extremely fine-tuned future precursor operator to the perturbed state in S U ( 2 K ) . Full article
(This article belongs to the Special Issue Black Hole Physics and Astrophysics)
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