Cosmic-Ray Acceleration in Radio-jet Shear Flows: Scattering Inside and Outside the Jet

A steady-state, analytical model of energetic particle acceleration in radio-jet shear flows due to cosmic-ray viscosity is explored, including particle scattering both into and out of the shear flow acceleration region. This involves solving a mixed Dirichlet-Von Neumann boundary value problem at t...

Full description

Saved in:
Bibliographic Details
Published in:The Astrophysical journal 2020-05, Vol.894 (2), p.95
Main Authors: Webb, G. M., Mostafavi, P., Al-Nussirat, S., Barghouty, A. F., Li, G., le Roux, J. A., Zank, G. P.
Format: Article
Language:English
Subjects:
Active galactic nuclei
Alpha rays
Astronomical models
Astrophysics
Boundary value problems
Cosmic rays
Dirichlet problem
Energetic particles
Flow velocity
High energy astronomy
Momentum
Particle acceleration
Radio jets
Radio jets (astronomy)
Relativistic jets
Scattering
Shear flow
Steady state models
Transport equations
Ultra-high-energy cosmic radiation
Viscosity
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:A steady-state, analytical model of energetic particle acceleration in radio-jet shear flows due to cosmic-ray viscosity is explored, including particle scattering both into and out of the shear flow acceleration region. This involves solving a mixed Dirichlet-Von Neumann boundary value problem at the edge of the jet. The spectrum of the accelerated particles is harder than the free-escape case from the edge of the jet. The flow velocity u = u(r) ez is along the axis of jet (the z-axis). u is independent of distance z along the jet axis, and u(r) is a monotonically decreasing function of cylindrical radius r from the jet axis. The scattering time where p is the particle momentum in the fluid frame in the shear flow region 0 < r < r2, and outside the jet (r > r2). Green's functions are obtained for monoenergetic injection of particles with momentum p = p0 at radius r = r1 (0 < r1 < r2). The Green's function and Green's formula are used to determine solutions for a general spectrum of particles at . Solutions are obtained corresponding to a monoenergetic spectrum at infinity. We discuss the implications of these results for the acceleration of ultra-high-energy cosmic-rays in active galactic nucleus jet sources. Leaky box models of particle acceleration in shear flows, including synchrotron losses and particle escape, are used to describe the momentum spectrum of accelerated particles. The use of the relativistic telegrapher transport equation model is discussed.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/ab8635