Plasma Regimes in the Surroundings of Black Holes, Composite Plasma Disk Structures and Relevant Accretion Processes

Abstract

The theory of the composite plasma disk structures and of the relevant magnetic field configurations that can surround black holes is presented, consistently with recent experimental observations indicating that highly coherent magnetic field configurations exist in the core of these structures. Concepts developed to describe the physics of magnetically confined laboratory plasmas are used. Thus the “paradox”, that arises when considering accreting plasmas in the presence of a transverse magnetic field is resolved by considering accretion as an intermittent process whereby particles are carried in steps, along a sequence of magnetic separatrices containing the formed magnetic islands, by the onset of the equivalent of “edge localized modes” (ELMs) observed in laboratory experiments. Inactive galactic black holes are suggested as being associated with older galaxies that have been subjected to collisions destroying the coherent structures needed to guide relevant accretion flows. Alternatively, tridimensional spiral structures can emerge from axisymmetric disk configurations in a region close to the black hole and guide the relevant accretion flows. The radial gradient of the rotation frequency and the vertical gradient of the plasma pressure are the excitation factors for spirals as well as for axisymmetric modes. These can produce vertical flows of thermal energy and particles in opposing directions that can be connected to the winds emanating from disks in Active Galactic Nuclei (AGNs). In the close vicinity of Binary Black Holes the existence of three characteristic plasma regions is envisioned. The intermediate of these regions exhibits three physical regimes that differ both for the magnetic field structure and the spectrum of the emitted radiation, with jets and High Frequency Periodic Oscillations (HFQPOs) produced in two of these regimes.