천문우주과학과

일시: 2022년 12월 8일 목요일 오전 10시 자4514호(세미나실)

연사: Huirong Yan교수(독일 포츠담대학교/DESI) 

제목: Magnetohydrodynamic Turbulence and Cosmic Ray Transport   

초록: 

  Cosmic ray propagation is determined by the properties of interstellar turbulence. The multiphase nature of ISM and diversity of driving mechanisms give rise to spatial variation of turbulence properties. A new chapter of CR propagation research has begun when studies of particle transport and interstellar turbulence can confront each other. I shall report our current understandings of MHD turbulence and particle transport. In particular, the proportion of magnetosonic modes is revealed to increase with increasing compressive forcing from turbulence simulations, which entails an extra spatial dependence of cosmic rays transport. Both theoretical and observational studies will be presented. With the advanced technique we developed, it is found that Alfven and magnetosonic modes are distinguishable from observations. Clear signatures of critically balanced turbulence as well as the compressible modes are revealed from both space and astro plasma. Different regimes of particle transport, e.g., diffusion vs. superdiffusion, isotropic vs. anisotropic diffusion, will be discussed in relation to turbulence properties.