Abstract
The origin of high-energy particles in the Universe is one of the key issues of high-energy solar physics, space science, astrophysics, and particle astrophysics. Charged particles in astrophysical plasmas can be accelerated to very high energies by electric fields. Based on the characteristics of interactions between charged particles and electric fields carried by the background plasma, the mechanisms of charged particle acceleration can be divided into several groups: resonant interactions between plasma waves and particles, acceleration by electric fields parallel to magnetic fields, and acceleration caused by drift of the guiding center of particle gyro-motion around magnetic fields in magnetic field in-homogeneity-related curvature and gradient, etc. According to macroscopic energy conversion mechanisms leading to acceleration of particles, several theories of particle acceleration have been developed: stochastic particle acceleration by turbulent electromagnetic fields, diffusive shock acceleration of particles, and particle acceleration during magnetic re-connections. These theories have their own assumptions and characteristics and find applications in different astrophysical contexts. With advances in high-energy astrophysical observations and in combination with analyses of characteristics of high-energy particle acceleration and radiation, we can better understand the underlying physical processes in dramatically evolving astrophysical environments.
Highlights
The origin of high-energy astrophysics can be traced back to the early 20th century when cosmic rays, high energy particles that can ionize gases in the atmosphere, were discovered by Victor Francis Hess (1936 Nobel Laureate in Physics
The acceleration of energetic particles becomes a key issue in high-energy space science, high-energy solar physics, high-energy astrophysics, and particle astrophysics
The stochastic particle acceleration mechanism originally proposed by Fermi is still the starting point of most macroscopic theories of particle acceleration (Fermi, 1949; Parker, 1958; Toptygin, 1980; Petrosian and Liu, 2004)
Summary
The origin of high-energy astrophysics can be traced back to the early 20th century when cosmic rays, high energy particles that can ionize gases in the atmosphere, were discovered by Victor Francis Hess (1936 Nobel Laureate in Physics). The stochastic particle acceleration mechanism originally proposed by Fermi (i.e., charged particles are accelerated gradually to higher energies via stochastic interactions with electromagnetic field fluctuations carried by the background plasma) is still the starting point of most macroscopic theories of particle acceleration (Fermi, 1949; Parker, 1958; Toptygin, 1980; Petrosian and Liu, 2004) Current researches in this area focus on using the associated radiation mechanisms to infer distribution function of energetic particles from observations, in combination with the relevant energy release processes (such as magnetic reconnection, shocks, MHD instabilities, etc.), analyzing the related particle acceleration and transport, plasma heating, and magnetic field amplification processes. This review is organized as the following: General Characteristics of HIGH-ENERGY Particle Acceleration in a Fluid discusses microscopic interactions leading to changes in particle energy; Specific Acceleration Mechanisms summarize particle acceleration in specific astrophysical conditions; Conclusions are drawn in Conclusion
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
