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      Very High-Energy Emission from the Direct Vicinity of Rapidly Rotating Black Holes

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          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          When a black hole accretes plasmas at very low accretion rate, an advection-dominated accretion flow (ADAF) is formed. In an ADAF, relativistic electrons emit soft gamma-rays via Bremsstrahlung. Some MeV photons collide with each other to materialize as electron-positron pairs in the magnetosphere. Such pairs efficiently screen the electric field along the magnetic field lines, when the accretion rate is typically greater than 0.03-0.3% of the Eddington rate. However, when the accretion rate becomes smaller than this value, the number density of the created pairs becomes less than the rotationally induced Goldreich-Julian density. In such a charge-starved magnetosphere, an electric field arises along the magnetic field lines to accelerate charged leptons into ultra-relativistic energies, leading to an efficient TeV emission via an inverse-Compton (C) process, spending a portion of the extracted hole's rotational energy. In this review, we summarize the stationary lepton accelerator models in black hole magnetospheres. We apply the model to super-massive black holes and demonstrate that nearby low-luminosity active galactic nuclei are capable of emitting detectable gamma-rays between 0.1 and 30 TeV with the Cherenkov Telescope Array.

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          Most cited references 54

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          Gamma-Ray Pulsars: Radiation Processes in the Outer Magnetosphere

           Roger Romani (1996)
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            High-Resolution X-ray imaging and spectroscopy of N 103B

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              Magnetohydrodynamic production of relativistic jets.

               D Meier,  S Koide,  Y Uchida (2001)
              A number of astronomical systems have been discovered that generate collimated flows of plasma with velocities close to the speed of light. In all cases, the central object is probably a neutron star or black hole and is either accreting material from other stars or is in the initial violent stages of formation. Supercomputer simulations of the production of relativistic jets have been based on a magnetohydrodynamic model, in which differential rotation in the system creates a magnetic coil that simultaneously expels and pinches some of the infalling material. The model may explain the basic features of observed jets, including their speed and amount of collimation, and some of the details in the behavior and statistics of different jet-producing sources.
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                Author and article information

                Journal
                22 November 2018
                Article
                10.3390/galaxies6040122
                1811.09349

                http://arxiv.org/licenses/nonexclusive-distrib/1.0/

                Custom metadata
                Galaxies 2018, 6, 122
                Invited review article, published in Radio Galaxies at TeV Energies, special issue of Galaxies; 37 pages, 18 figures
                astro-ph.HE

                High energy astrophysical phenomena

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