Particle Acceleration by Cosmic Ray Viscosity in Radio-jet Shear Flows
Particle Acceleration by Cosmic Ray Viscosity in Radio-jet Shear Flows
复制标题
无线电射流剪切流中宇宙射线粘度的粒子加速
作者：
G. Webb;S. Al;P. Mostafavi;A. Barghouty;G. Li;J. L. le Roux;G. Zank
探讨了相对论喷流中高能带电粒子由于宇宙线粘性和流体剪切而加速的稳态分析模型。该模型将Webb等人的工作扩展到平均散射时间τ（r，p）的其他形式。射流的流速分布u = u（r）ez与沿着射流轴线的距离z无关。u（r）是关于射流轴线的圆柱半径r的单调递减函数。散射时间是在流体坐标系中测量的粒子动量p的幂律函数。这些解是涉及J 0贝塞尔函数和p的幂律函数的本征函数展开。这些解用于讨论射流中剪切流中的粒子加速，并确定高能宇宙射线（即，具有动能T EeV）的粒子可以在候选活动星系核喷流源中加速到这些能量。绿色的功能解决方案，涉及JM贝塞尔函数和更一般的边界条件在射流的外缘。我们使用一个依赖于时间的模型来评估宇宙射线惯性在限制由于宇宙射线粘性和由于阿尔文波的二阶费米加速的上部粒子动量pmax（t）的影响。该模型描述了由于动量空间扩散的能量增益和由于同步辐射损失或逆康普顿损失的粒子的能量损失之间的竞争。
A steady-state, analytical model for the acceleration of energetic charged particles owing to cosmic ray viscosity and fluid shear in relativistic jets is explored. The model extends the work of Webb et al. to alternative forms of the mean scattering time τ (r, p). The flow velocity profile u = u(r) ez of the jet is independent of distance z along the axis of the jet. u(r) is a monotonic decreasing function of cylindrical radius r about the jet axis. The scattering time is a power-law function of the particle momentum p as measured in the fluid frame. The solutions are eigenfunction expansions involving J0 Bessel functions and power-law functions of p. The solutions are used to discuss particle acceleration in shear flows in jets, and to determine if high-energy cosmic rays (i.e., with kinetic energies T ∼ EeV) can be accelerated to these energies in candidate AGN jet sources. Green’s function solutions involving Jm Bessel functions and more general boundary conditions at the outer edge of the jet are described. We use a time-dependent model to assess the effects of cosmic ray inertia in limiting the upper particle momentum pmax(t) due to cosmic ray viscosity and from second-order Fermi acceleration due to Alfvén waves. The model describes the competition between energy gains due to momentum space diffusion and energy losses of the particles due to synchrotron losses or inverse Compton losses.
DOI：
10.3847/1538-4357/aa7410
发表时间：
2017-06
期刊：
The Astrophysical Journal
影响因子：
--
作者：
Ruo-Yu Liu;F. Rieger;F. Aharonian
通讯作者：
Ruo-Yu Liu;F. Rieger;F. Aharonian
DOI：
10.3847/1538-4357/833/1/34
发表时间：
2016-11
期刊：
The Astrophysical Journal
影响因子：
--
作者：
F. Rieger;P. Duffy
通讯作者：
F. Rieger;P. Duffy
DOI：
10.3847/1538-4357/aaeb91
发表时间：
2018-11
期刊：
The Astrophysical Journal
影响因子：
--
作者：
P. Mostafavi;G. Zank;G. Webb
通讯作者：
P. Mostafavi;G. Zank;G. Webb