scholarly journals STOCHASTIC ELECTRON ACCELERATION IN SNR RX J1713.7-3946

2013 ◽  
Vol 23 ◽  
pp. 319-323 ◽  
Author(s):  
ZHONGHUI FAN ◽  
SIMING LIU

Stochastic acceleration of charged particles due to their interactions with plasma waves may be responsible for producing superthermal particles in a variety of astrophysical systems. This process can be described as a diffusion process in the energy space with the Fokker-Planck equation. In this paper, a time-dependent numerical code is used to solve the reduced Fokker-Planck equation involving only time and energy variables with general forms of the diffusion coefficients. We also propose a self-similar model for particle acceleration in Sedov explosions and use the TeV SNR RX J1713.7-3946 as an example to demonstrate the model characteristics. Markov Chain Monte Carlo method is utilized to constrain model parameters with observations.

In two recent papers a method of calculation of the coefficients of the Fokker-Planck equa­tion which includes in a proper way correlation effects between distant particles has been expounded. In this paper the theory is extended to include a proper treatment of close binary encounters. It is also shown that the higher-order terms of the Fokker-Planck equation may be summed to produce a Boltzmann-like contribution to the collision term. Finally, it is shown that in the approximation in which only ‘dominant’ terms are retained, the theory reproduces a number of well-known formulae, including the ordinary Boltzmann collision term, but now with a suitable cut-off built in.


2015 ◽  
Vol 22 (11) ◽  
pp. 113706
Author(s):  
M. Bakhtiyari-Ramezani ◽  
J. Mahmoodi ◽  
N. Alinejad

In a recent paper (Thompson & Hubbard 1960) it was shown how the diffusion coefficients of the Fokker-Planck equation could be calculated in the case of a plasma in thermal equilibrium by a method which included automatically correlation effects and avoided the use of a cut-off procedure. In this paper the method is extended to plasmas not in thermal equilibrium and a calculation of the friction coefficient is given.


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