Electromagnetic Extraction of Energy from Kerr Black Holes
By I. Okamoto. 2005
473 citations recorded by the source corpus.
The energy extraction process from Kerr black holes is elucidated compared with that from pulsars in force-free degenerate electrodynamics (FFDE). It is argued for the force-free magnetosphere of a Kerr black hole in a steady axisymmetric state that the function of unipolar inductors in the presence of global magnetic fluxes threading the horizon is equipped by a frame-dragging effect in the Kerr spacetime metric to the upper null surface, SN, with the axial distance, � N, where the local value of the angular velocity of the frame-dragging, ω, is equal to the rotational frequency of each field line, i.e., ω(� N )= ΩF, and the rotational velocity of each field line, vF, measured by “zeroangular-momentum-observers” changes in sign. There must be a pair-creation gap at SN, from which the paired winds, ingoing and outgoing, are initiated. The poloidal electric current, I, for each wind is determined by solving the eigenvalue problem with the “criticality condition” imposed at the fast surfaces nearly at the horizon and at infinity, and the “current-closure condition” at SN determines the ultimate eigenvalues of ΩF and I in terms of the hole’s angular velocity, ΩH = ω(rH), and the distribution of the magnetic flux at the horizon. It is not in the ordinary ergosphere, but in the effective ergosphere in the region of ΩH >ω> ΩF and vF < 0 that general-relativistic effects play the most significant role for electromagnetic extraction of the hole’s energy. The flow there must be regarded as an ingoing magneto-centrifugal wind, rather than an accretion flow. In a kind of extreme state that “force-free” field lines be frozen in “massless” particles in FFDE, the “membrane paradigm” combined with the DC circuit model is useful in black hole as well as pulsar magnetospheres.
Subfields: Astronomy and Astrophysics
View Paper: https://www.semanticscholar.org/paper/9d5c4ce9a7cd16a05cb071ea9faacedb74c193f4
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In Astronomy and Astrophysics
Citations in the corpus
- The physics of gamma-ray bursts & relativistic jets (2014, methodology): “(248) The spin-dependent function F (a∗) needs full general relativity to solve (Blandford and Znajek, 1977).”
- The Masses and Spins of Neutron Stars and Stellar-Mass Black Holes (2014, background): “This activity makes GRS 1915+105 a particularly interesting source in which to try measure the black hole spin, since spin may power jets ([270]).”
- Cool outflows in galaxies and their implications (2020, background): “…accelerated by processes associated with the magnetized accretion disk (e.g., Blandford and Payne 1982; Lynden-Bell 2003, 2006; Hawley and Krolik 2006), but may be larger in cases where the kinetic energy is delivered by jets produced by the Blandford-Znajek mechanism (Blandford and Znajek 1977).”
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- Science with the space-based interferometer eLISA. III: probing the expansion of the universe using gravitational wave standard sirens (2016, background): “Besides this effect, which is due to the twisting of magnetic field lines by the rapidly inspiralling MBHB, accretion also powers standard radio jets through the Blandford-Znajeck effect [76], with luminosity dependent on the mass accretion rate.”
- The black hole accretion code (2016, background): “The agreement can be considered as very good, that is apart from a slightly higher magnetisation in HARM for r ∈ [20, 30], the differences of which are well within the 1σ standard deviation over the averaging time.”