Journal of Physics & Astronomy

J. Z. G. Ma ¹

Affiliations
1 California Institute of Integral Studies, San Francisco, CA, US

Abstract

Since the discovery of Quasars, giant magnetic flares about Kerr black holes (BHs) have drawn much attention to elucidate the mechanism of astrophysical high-energy phenomena and processes, such as quasi-periodic oscillations (QPOs), γ-ray bursts (GRBs), and outflow jets. Up to now, three kinds of flares are suggested: quasi-solar flares, cascade flares, and outflow flares. Both BH-dynamo theory in Gravitomagnetic (GM) field and force-free magnetosphere are developed in the curved 4D space-time by the manipulation of the 3+1 split of geometry (i.e., 3D in space+1D in time). We introduce first of all the disk-corona model of giant flares. Then, we describe the BH dynamo processes in the GM Field. Furthermore, we overview the magnetic topology of BH magnetosphere, helicity transfer, and the Penrose process. Finally, we provide a summary on the future work of the giant flare physics. It is predicted that the dynamics of the high-energy radiation in giant flares will be brought to light by the investigation of the general relativistic magnetohydrodynamic (GRMHD) dynamo action outside the central BHs residing in a tokamak-like cosmic magnetic field.

Keywords

Magnetic Flare, Kerr Black Hole, Gravitomagnetic Field, Force-Free Magnetosphere, Penrose Process, General Relativistic Magnetohydrodynamic Dynamo.

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J. Z. G. Ma ¹

Affiliations
1 California Institute of Integral Studies, San Francisco, CA, US

Abstract

ASCA observations present broad iron (Fe) Kα emission lines in Seyfert(-like) AGNs. The line is explained to originate from a thin disk surrounding the central black hole (BH) which is either rotating or non-rotating. Based on previous theoretical and observational studies, we propose a non-disk thin-torus to exist in the inner region of the disk around a Kerr (rotating) BH. We develop the commonly-used thin-disk model to the thin torus model in this special region under the Kerr metric and calculate the profiles of the Fe K α lines. By extending previous work, we formulate in details the emission mechanism in this paper. The spectra of a sample galaxy, NGC 3516, is then revisited. New results are as follows: (1) the central BH is not static but rotating, with a dimensionless specific angular momentum, a>0.4, the best-fit of which is 0.9; (2) the radial position of the thin torus is within (20-40)r_g, where r_g is the gravitational radius of the BH; (3) the inclination angle θ0 of the observer is smaller than 50°; and, (4) the extension of torus to both sides of the equatorial plane can reach 67.3°. Specifically, simulations expose that the so-called "absorption" feature of the line spectrum around 6.0 key may not be realistic; and, the humps and troughs of the broad line spectra are contributed by the four types of particles around the central BH.

Keywords

Black Hole, Fe Kα Lines, AGNs, Seyfert, Kerr Metric, Photons, NGC.

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