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Title: Acceleration of relativistic electrons by magnetohydrodynamic turbulence: Implications for non-thermal emission from black hole accretion disks

We use analytic estimates and numerical simulations of test particles interacting with magnetohydrodynamic (MHD) turbulence to show that subsonic MHD turbulence produces efficient second-order Fermi acceleration of relativistic particles. This acceleration is not well described by standard quasi-linear theory but is a consequence of resonance broadening of wave-particle interactions in MHD turbulence. We provide momentum diffusion coefficients that can be used for astrophysical and heliospheric applications and discuss the implications of our results for accretion flows onto black holes. In particular, we show that particle acceleration by subsonic turbulence in radiatively inefficient accretion flows can produce a non-thermal tail in the electron distribution function that is likely important for modeling and interpreting the emission from low-luminosity systems such as Sgr A* and M87.
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. Physics Department, University of California, Berkeley, CA 94720 (United States)
  2. Astronomy Department and Theoretical Astrophysics Center, University of California, Berkeley, CA 94720 (United States)
  3. Space Science Center and Department of Physics, University of New Hampshire, Durham, NH 03824 (United States)
  4. Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8 (Canada)
Publication Date:
OSTI Identifier:
22365359
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 791; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; ACCRETION DISKS; ASTROPHYSICS; BLACK HOLES; COMPUTERIZED SIMULATION; DIFFUSION; DISTRIBUTION FUNCTIONS; ELECTRONS; EMISSION; LUMINOSITY; MAGNETOHYDRODYNAMICS; PLASMA; RELATIVISTIC RANGE; TURBULENCE