Very High-Energy Emission from the Direct Vicinity of Rapidly Rotating Black Holes
AbstractWhen 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 (IC) 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. View Full-Text
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Hirotani, K. Very High-Energy Emission from the Direct Vicinity of Rapidly Rotating Black Holes. Galaxies 2018, 6, 122.
Hirotani K. Very High-Energy Emission from the Direct Vicinity of Rapidly Rotating Black Holes. Galaxies. 2018; 6(4):122.Chicago/Turabian Style
Hirotani, Kouichi. 2018. "Very High-Energy Emission from the Direct Vicinity of Rapidly Rotating Black Holes." Galaxies 6, no. 4: 122.
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