%AKimura, Shigeo [Department of Physics, Pennsylvania State University, University Park, PA 16802, USA, Center for Particle and Gravitational Astrophysics, Pennsylvania State University, University Park, PA 16802, USA, Department of Astronomy & Astrophysics, Pennsylvania State University, University Park, PA 16802, USA]%ATomida, Kengo [Department of Earth & Space Science, Osaka University, Osaka 560-0043, Japan, Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA]%AMurase, Kohta [Department of Physics, Pennsylvania State University, University Park, PA 16802, USA, Center for Particle and Gravitational Astrophysics, Pennsylvania State University, University Park, PA 16802, USA, Department of Astronomy & Astrophysics, Pennsylvania State University, University Park, PA 16802, USA, Center for Gravitational Physics, Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 Japan]%BJournal Name: Monthly Notices of the Royal Astronomical Society; Journal Volume: 485; Journal Issue: 1; Related Information: CHORUS Timestamp: 2019-12-16 23:17:29 %D2019%IOxford University Press; None %JJournal Name: Monthly Notices of the Royal Astronomical Society; Journal Volume: 485; Journal Issue: 1; Related Information: CHORUS Timestamp: 2019-12-16 23:17:29 %K %MOSTI ID: 10127575 %PMedium: X %TAcceleration and escape processes of high-energy particles in turbulence inside hot accretion flows %XAbstract

We investigate acceleration and propagation processes of high-energy particles inside hot accretion flows. The magnetorotational instability (MRI) creates turbulence inside accretion flows, which triggers magnetic reconnection and may produce non-thermal particles. They can be further accelerated stochastically by the turbulence. To probe the properties of such relativistic particles, we perform magnetohydrodynamic simulations to obtain the turbulent fields generated by the MRI, and calculate orbits of the high-energy particles using snapshot data of the MRI turbulence. We find that the particle acceleration is described by a diffusion phenomenon in energy space with a diffusion coefficient of the hard-sphere type: Dε ∝ ε2, where ε is the particle energy. Eddies in the largest scale of the turbulence play a dominant role in the acceleration process. On the other hand, the stochastic behaviour in configuration space is not usual diffusion but superdiffusion: the radial displacement increases with time faster than that in the normal diffusion. Also, the magnetic field configuration in the hot accretion flow creates outward bulk motion of high-energy particles. This bulk motion is more effective than the diffusive motion for higher energy particles. Our results imply that typical active galactic nuclei that host hot accretion flows can accelerate CRs up to ε ∼ 0.1−10 PeV.

%0Journal Article