The Cosmic Battery in Astrophysical Accretion Disks

Abstract

The aberrated radiation pressure at the inner edge of the accretion disk around an astrophysical black hole imparts a relative azimuthal velocity on the electrons with respect to the ions which gives rise to a ring electric current that generates large scale poloidal magnetic field loops. This is the Cosmic Battery established by Contopoulos and Kazanas in 1998. In the present work we perform realistic numerical simulations of this important astrophysical mechanism in advection-dominated accretion flows-ADAF. We confirm the original prediction that the inner parts of the loops are continuously advected toward the central black hole and contribute to the growth of the large scale magnetic field, whereas the outer parts of the loops are continuously diffusing outward through the turbulent accretion flow. This process of inward advection of the axial field and outward diffusion of the return field proceeds all the way to equipartition, thus generating astrophysically significant magnetic fields on astrophysically relevant timescales. We confirm that there exists a critical value of the magnetic Prandtl number between unity and 10 in the outer disk above which the Cosmic Battery mechanism is suppressed.

11 pages, 5 figures, acceped for publication in the Astrophysical Journal

References in corpus (10)

• Advection-Dominated Accretion and the Black Hole Event Horizon
• Particle acceleration in axisymmetric pulsar current sheets
• Three-dimensional numerical simulations of the pulsar magentoshere: Preliminary results
• Magnetized Tori around Kerr Black Holes: Analytic Solutions with a Toroidal Magnetic Field
• Black-hole jets without large-scale net magnetic flux
• Advection/Diffusion of Large-Scale B-Field in Accretion Disks
• Black Hole Magnetospheres
• The Cosmic Battery Revisited
• Simulations of the Poynting--Robertson Cosmic Battery in Resistive Accretion Disks
• Accretion disk radiation dynamics and the cosmic battery

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• Magnetic field structure in the vicinity of a super-massive black hole in low luminosity galaxies: the case of Sgr A*
• Episodic Jets from Black Hole Accretion Disks
• The energy distribution of electrons in radio jets
• The immediate environment of an astrophysical black hole
• Magnetic seed generation by plasma heat flux in accretion disks
• Radiative transfer dynamo effect