scholarly journals Electrically-charged black holes and the Blandford-Znajek mechanism

2021 ◽  
Author(s):  
Serguei S Komissarov
Keyword(s):  
Magnetic Field ◽  
Black Holes ◽  
Black Hole ◽  
Electric Charge ◽  
Meissner Effect ◽  
Charged Black Holes ◽  
Field Lines ◽  
The One ◽  
Electrically Charged ◽  
The Magnetic Field

Abstract Recently, it was claimed by King & Pringle that accretion of electric charge by a black hole rotating in an aligned external magnetic field results in a “dead” vacuum magnetosphere, where the electric field is totally screened, no vacuum breakdown is possible, and the Blandford-Znajek mechanism cannot operate. Here we study in details the properties of the Wald solution for electrically charged black holes discussed in their paper. Our results show that the claim is erroneous as in the solution with the critical charge q0 = 2aB0 there exists a drop of electrostatic potential along all magnetic field lines except the one coinciding with the symmetry axis. It is also found that while uncharged rotating black holes expel external vacuum magnetic field from their event horizon (the Meissner effect), electric charging of black holes pulls the magnetic field lines back on it, resembling what has been observed in some previous force-free, RMHD and PIC simulations of black hole magnetospheres. This suggests that accretion of electric charge may indeed be a feature of the black hole electrodynamics. However, our analysis shows that the value q0 of the BH charge given by Wald is likely to be only an upper limit, and that the actual value depends of the details of the magnetospheric physics.

scholarly journals Very High-Energy Emission from the Direct Vicinity of Rapidly Rotating Black Holes

Galaxies ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 122 ◽  
Author(s):  
Kouichi Hirotani
Keyword(s):  
Magnetic Field ◽  
Black Holes ◽  
Black Hole ◽  
Electric Field ◽  
Gamma Rays ◽  
Accretion Rate ◽  
High Energy ◽  
Relativistic Electrons ◽  
Field Lines ◽  
The Magnetic Field

When a black hole accretes plasmas at very low accretion rate, an advection-dominated accretion flow (ADAF) is formed. In an ADAF, relativistic electrons emit soft gamma-rays via Bremsstrahlung. Some MeV photons collide with each other to materialize as electron-positron pairs in the magnetosphere. Such pairs efficiently screen the electric field along the magnetic field lines, when the accretion rate is typically greater than 0.03–0.3% of the Eddington rate. However, when the accretion rate becomes smaller than this value, the number density of the created pairs becomes less than the rotationally induced Goldreich–Julian density. In such a charge-starved magnetosphere, an electric field arises along the magnetic field lines to accelerate charged leptons into ultra-relativistic energies, leading to an efficient TeV emission via an inverse-Compton (IC) process, spending a portion of the extracted hole’s rotational energy. In this review, we summarize the stationary lepton accelerator models in black hole magnetospheres. We apply the model to super-massive black holes and demonstrate that nearby low-luminosity active galactic nuclei are capable of emitting detectable gamma-rays between 0.1 and 30 TeV with the Cherenkov Telescope Array.

scholarly journals Comments on magnetic black holes

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Juan Maldacena
Keyword(s):  
Magnetic Field ◽  
Black Holes ◽  
Radiation Effects ◽  
Magnetic Charge ◽  
Two Dimensional ◽  
Electroweak Symmetry ◽  
Charged Black Holes ◽  
The Standard Model ◽  
Field Lines ◽  
The Magnetic Field

Abstract We discuss aspects of magnetically charged black holes in the Standard Model. For a range of charges, we argue that the electroweak symmetry is restored in the near horizon region. The extent of this phase can be macroscopic. If Q is the integer magnetic charge, the fermions lead to order Q massless two dimensional fermions moving along the magnetic field lines. These greatly enhance Hawking radiation effects.

scholarly journals ELECTRIC CHARGE ESTIMATION OF A NEWBORN BLACK HOLE

2009 ◽  
Vol 18 (13) ◽  
pp. 2035-2045 ◽  
Author(s):  
ANTON BAUSHEV ◽  
PASCAL CHARDONNET
Keyword(s):  
Magnetic Field ◽  
Black Holes ◽  
Black Hole ◽  
Electric Charge ◽  
Charge Separation ◽  
Mass Ratio ◽  
Hole Formation ◽  
Upper Limit ◽  
Good Conductor ◽  
Charge Formula

Though a black hole can theoretically possess a very big charge ([Formula: see text]), the charge of the real astrophysical black holes is usually considered to be negligible. This supposition is based on the fact that an astrophysical black hole is always surrounded by some plasma, which is a very good conductor. However, it disregards the fact that black holes usually have some angular momentum, which can be interpreted as their rotation of a sort. If in the plasma surrounding the hole there is some magnetic field, it leads to electric field creation and, consequently, charge separation. In this article we estimate the upper limit of the electric charge of stellar mass astrophysical black holes. We have considered a new black hole formation process and shown that the charge of a newborn black hole can be significant (~ 1013 C ). Though the obtained charge of an astrophysical black hole is big, the charge-to-mass ratio is small, [Formula: see text], and it is not enough to affect significantly either the gravitational field of the star or the dynamics of its collapse.

scholarly journals S-DUALITY AND THE ENTROPY OF BLACK HOLES IN HETEROTIC STRING THEORY

1996 ◽  
Vol 11 (39n40) ◽  
pp. 3103-3111 ◽  
Author(s):  
AMIT GHOSH ◽  
JNANADEVA MAHARANA
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Partition Function ◽  
Heterotic String ◽  
Heterotic String Theory ◽  
Charged Black Holes ◽  
Duality Transformations ◽  
Extremal Limit ◽  
Electrically Charged ◽  
Black Hole Solutions

Four-dimensional heterotic string effective action is known to admit non-rotating electrically and magnetically charged black hole solutions. The partition function and entropy is computed for electrically charged black holes and is vanishing in some extremal limit. For the magnetically charged black holes the entropy is also argued to be vanishing in the same extremal limit when these black hole solutions are related by S-duality transformations.

scholarly journals MOTION OF CHARGED PARTICLES ON THE REISSNER–NORDSTRÖM (ANTI)-DE SITTER BLACK HOLE SPACETIME

2011 ◽  
Vol 26 (39) ◽  
pp. 2923-2950 ◽  
Author(s):  
MARCO OLIVARES ◽  
JOEL SAAVEDRA ◽  
CARLOS LEIVA ◽  
JOSÉ R. VILLANUEVA
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Charged Particles ◽  
De Sitter ◽  
Point Particles ◽  
Charged Black Holes ◽  
Black Hole Spacetime ◽  
Jacobi Functions ◽  
Electrically Charged ◽  
Charged Point

We study the motion of relativistic, electrically charged point particles in the background of charged black holes with nontrivial asymptotic behavior. We compute the exact trajectories of massive particles and express them in terms of elliptic Jacobi functions. As a result, we obtain a detailed description of particles orbits in the gravitational field of Reissner–Nordström (anti)-de Sitter black hole, depending of their charge, mass and energy.

scholarly journals CONSTRAINTS ON X-RAY POLARIZATION OF SYNCHROTRON JETS FROM STELLAR-MASS BLACK HOLES

2012 ◽  
Vol 08 ◽  
pp. 102-107
Author(s):  
D. M. RUSSELL
Keyword(s):  
Magnetic Field ◽  
Black Holes ◽  
Black Hole ◽  
Synchrotron Emission ◽  
Relativistic Jets ◽  
X Ray ◽  
Linearly Polarized ◽  
Hard State ◽  
X Ray Binaries ◽  
The Magnetic Field

For most black hole X-ray binaries, the fraction of X-ray flux originating in the synchrotron jets is generally thought to be low in the hard state. However in one intriguing case, the infrared – X-ray correlations, evolution of broadband spectra and timing signatures suggest that synchrotron emission from a jet likely dominated both the infrared and X-ray flux on the hard state decline of an outburst of XTE J1550–564 at a luminosity of ~ (2 × 10-4 – 2 × 10-3) L Edd . Synchrotron emission from the relativistic jets launched close to black holes can be highly linearly polarized, depending on the configuration of the magnetic field. It has recently been shown that the polarimetric signature of their jets is detected in the infrared and is highly variable. This reveals the magnetic geometry in a region of the compact jet near its base, close to the black hole. From these results, it is predicted that in some cases, high (possibly up to 10%), variable levels of X-ray polarization from synchrotron emission originating in jets will be detected from accreting black holes by future spaceborne X-ray polarimeters.

Plasma flows in a converging and diverging configuration and the associated plasma particle acceleration: kinetic approach

1975 ◽  
Vol 13 (3) ◽  
pp. 481-497 ◽  
Author(s):  
M. Fridman
Keyword(s):  
Magnetic Field ◽  
Average Velocity ◽  
Particle Flux ◽  
Plasma Particle ◽  
Series Development ◽  
Field Lines ◽  
The One ◽  
The Relationship ◽  
The Magnetic Field ◽  
Transport Laws

Transport laws in collisionless systems must be derived from the one-particle Liouville equation. The simplest cases are those of the CGL invariants along the magnetic field lines, together with the resulting equations of continuity and motion, in circumstances where a supersonic particle flux is parallel to a diminishing magnetic field. We give functional expressions for the two contributions to the parallel heat flux, with integrated forms of kinetic theory. The general expressions, corresponding to the moments of greater order, coincide with those obtained by series development of the differential equation of moments. Moreover, we illustrate a case of both parallel and convergent flux, for which the equation of continuity gives considerable acceleration to the precipitation flux average velocity in the absence of any important electric field, because that acceleration is important in understanding the relationship between the plasmasheet and the ionosphere.

scholarly journals Dissipation of Turbulent Magnetic Fields in Accreting Black Holes

1997 ◽  
Vol 163 ◽  
pp. 749-750 ◽  
Author(s):  
Victor Kowalenko ◽  
Fulvio Melia
Keyword(s):  
Magnetic Field ◽  
Black Holes ◽  
Black Hole ◽  
Magnetic Fields ◽  
Magnetic Field Intensity ◽  
Tearing Mode ◽  
Massive Black Hole ◽  
Basic Principles ◽  
Alternative Approach ◽  
The Magnetic Field

AbstractCalculations of the spectrum resulting from accretion onto a massive black hole often make use of the “equipartition assumption” in order to estimate the magnetic field intensity. Thus, the mechanism for the dissipation of the magnetic field and the resulting dynamical influence on the gas have not been treated quantitatively, nor self-consistently. Here, we introduce an alternative approach for modelling the magnetic field dissipation from basic principles, using current ideas about turbulent fields and tearing mode instabilities.

scholarly journals Superconducting properties of vacuum in strong magnetic field

2014 ◽  
Vol 23 (06) ◽  
pp. 1430009 ◽  
Author(s):  
M. N. Chernodub
Keyword(s):  
Magnetic Field ◽  
Strong Magnetic Field ◽  
W Bosons ◽  
Meissner Effect ◽  
Quantum Numbers ◽  
Anisotropic Superconductivity ◽  
Type Ii Superconductivity ◽  
Electroweak Model ◽  
Electrically Charged ◽  
The Magnetic Field

We discuss superconducting phases of vacuum induced by strong magnetic field in the electroweak model and in Quantum Chromodynamics (QCD) at zero temperature. In these phases, the vacuum behaves as an anisotropic inhomogeneous superconductor which supports superconductivity along the axis of the magnetic field while in the transversal directions, the superconductivity does not exist. The magnetic-field-induced anisotropic superconductivity appears as a result of condensation of electrically charged spin-one particles, which are elementary W bosons in the case of the electroweak model and composite quark–antiquark pairs with quantum numbers of ρ-mesons in the case of QCD. Due to the anisotropic nature of superconductivity, the Meissner effect is absent. Intrinsic inhomogeneities of the superconducting ground state are characterized by ensembles of certain topological vortices in an analogy with a mixed Abrikosov state of a type-II superconductivity.

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