Electrodynamics of black hole magnetospheres

By Komissarov S S. 2004

221 citations recorded by the source corpus.

The main goal of this research is to get better insights into the properties of the plasma-filled magnetospheres of black holes by means of direct numerical simulations and, ultimately, to resolve the controversy surrounding the Blandford-Znajek mechanism. Driven by the need to write the equations of black hole electrodynamics in a form convenient for numerical applications, we constructed a new system of 3 + 1 equations, which not only has a more traditional form than the now classic 3 + 1 system of Thorne and Macdonald but also is more general. To deal with the magnetospheric current sheets, we also developed a simple model of radiative resistivity based on the inverse Compton scattering of background photons. The results of numerical simulations combined with simple analytical arguments allow us to make a number of important conclusions on the nature of the Blandford-Znajek mechanism. We show that, just like in the Penrose mechanism and in the magnetohydrodynamic models of Punsly and Coroniti, the key role in this mechanism is played by the black hole ergosphere. The poloidal currents are driven by the gravitationally induced electric field, which cannot be screened within the ergosphere by any static distribution of the electric charge of locally created pair plasma. Contrary to what is expected in the membrane paradigm, the energy and angular momentum are extracted not only along the magnetic field lines penetrating the event horizon but also along all field lines penetrating the ergosphere. In dipolar magnetic configurations symmetric relative to the equatorial plane, the force-free approximation breaks down within the ergosphere, where a strong current sheet develops along the equatorial plane. This current sheet supplies energy and angular momentum at infinity to the surrounding force-free magnetosphere. The Blandford-Znajek monopole solution is found to be asymptotically stable and causal. The so-called horizon boundary condition of Znajek is shown to be a regularity condition at fast critical surface.

Subfields: Astronomy and Astrophysics, Geophysics

View Paper: https://www.semanticscholar.org/paper/a2fb8782a3f6b297b7b31983eda0aaa747c7b146

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Citations in the corpus

Beyond ideal MHD: towards a more realistic modelling of relativistic astrophysical plasmas (2008, background): “The second improvement consists of considering a non-scalar and anisotropic Ohm’s law, so that the behaviourof the currents in the magnetosphere can be described by using a very high conductivity along the magnetic lines and a negligiblysmall one in the transverse directions (Komissarov 2004).”
Simulations of the axisymmetric magnetospheres of neutron stars (2006, methodology): “The MHD simulations were carried out using a Godunovtype scheme that is described in Komissarov(1999; 2004b).”
Influence of Cosmic Repulsion and Magnetic Fields on Accretion Disks Rotating around Kerr Black Holes (2020, background): “Of course, the induced electric charge giving the electrostatic energy for particle acceleration should not be screened by plasma [95]—as shown in [96], the total screening needs the conditions”
General relativistic magnetohydrodynamic simulations of the jet formation and large-scale propagation from black hole accretion systems (2006, unknown): “In GRMHD numerical models of Poynting jets, the black hole’s polar region is always completely evacuated (McKinney & Gammie 2004; Komissarov 2004, 2005; De Villiers, Hawley, & Krolik 2003; De Villiers et al. 2005a).”
Electromagnetic Extraction of Energy from Kerr Black Holes (2005, background): “These criticality conditions are meaningful for the field lines threading both Sff∞ and Sff H where the surface currents are Joule-dissipated, but will be meaningless for the field lines threading the ergosphere (cf. Komissarov 2004).”
A Measurement of the Electromagnetic Luminosity of a Kerr Black Hole (2004, background): “There has been some concern about causality in the application of the force-free ap- proximation (e.g. Punsly 2003, see also Komissarov 2002, 2004a).”
Spacetime approach to force-free magnetospheres (2014, methodology): “This was shown using a different method by Komissarov (2004), who has given a detailed discussion of the properties of the light surfaces of Kerr.”
Time-dependent Force-free Pulsar Magnetospheres: Axisymmetric and Oblique Rotators (2006, methodology): “This is equivalent to replacing the parallel current with a resistive term σ‖E‖ (Komissarov 2004), where the parallel conductivity σ‖ is taken to infinity.”
The physics of gamma-ray bursts & relativistic jets (2014, background): “…relativistic MHD have led to significant progress in our understanding of the magnetic jet launching mechanism, propagation and acceleration (e.g. Komissarov, 2001, 2004; McKinney, 2006; Komissarov, 2007; Komissarov et al., 2007; McKinney and Narayan, 2007; Tchekhovskoy et al., 2008; Komissarov…”
Superradiance (2015, background): “tively use the disk as a battery. This is in fact the mechanism behind the electromotive force developed by rotating magnetized stars [442,443] and planets [444]. However, as was pointed out in Refs. [445,427] the membrane paradigm suggests that the horizon plays a similar role to the surface of a m”
ECHO: a Eulerian conservative high-order scheme for general relativistic magnetohydrodynamics and magnetodynamics (2007, methodology): “Notice that all the above relations are valid for both Boyer-Lindquist coordinates and Kerr-Schild coordinates (e.g. Komissarov 2004), which have non-vanishing gtr, gtφ, and grφ terms needed to remove the (unphysical) singularity at the event horizon.”
Superradiance: Energy Extraction, Black-Hole Bombs and Implications for Astrophysics and Particle Physics (2015, background): “[455, 442, 456, 457, 458]) and recent GRMHD simulations seem to indicate that magnetic fields generated by accretion disks have large split monopole components [445, 446, 447] suggesting that the BZ mechanism should occur in fully dynamical setups.”