Cosmic Ray Diffusion in the Multi-phase and Partially Ionized ISM
by
Tsung-Dao Lee Institute/S4F-SW - Open Area
Tsung-Dao Lee Institute
Host: Dong Lai
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Abstract:
Cosmic rays are a key non-thermal component of galaxies, yet their transport through the interstellar medium remains difficult to model because the ISM is turbulent, magnetized, multi-phase, and often only partially ionized. In this talk, I will discuss how these realistic ISM conditions reshape TeV–PeV cosmic-ray diffusion. I will show that MHD turbulence drives perpendicular superdiffusion through magnetic-field-line wandering, while compressibility, magnetic mirroring, ion–neutral damping, and thermal phase transitions regulate parallel scattering and confinement. These effects are especially important in cold and partially ionized gas, as well as for TeV–PeV cosmic rays propagating through a multi-phase ISM. I will also discuss how these transport mechanisms may help interpret recent LHAASO observations of Galactic PeVatrons and their extended TeV–PeV gamma-ray emission.
Biography:
Dr. Yue Hu is a NASA Hubble Fellow at the Institute for Advanced Study, Princeton. He received his Ph.D. in Physics from the University of Wisconsin–Madison in 2024, and his B.E. from Tongji University and the University of Bologna in 2018.His research spans astrophysical magnetism, MHD turbulence, cosmic rays, and multi-scale plasma physics across the ISM, CGM, and ICM. He develops novel statistical and machine learning techniques to map, for the first time, the large-scale magnetic fields threading the cosmic web. He has over 70 refereed publications, with work appearing in Nature Astronomy and Nature Communications. He is the recipient of the American Physical Society (APS) Cecilia Payne-Gaposchkin Dissertation Award and the Overseas Chinese Physics Association (OCPA) Outstanding Dissertation Award.
