2025/12/31(Wed) 14:00 -15:00 七樓研討室 7F, P7A Seminar Room
Title
Hadronic processes in large astrophysical structures
Speaker
Dr. Kinwah Wu (Mullard Space Science Laboratory,University College London, UK)Abstract
The largest structures in the Universe are cosmic filaments and voids. Below them in the hierarchy are super-clusters and galaxy clusters. These large astrophysical structures are permeated by magnetic fields, which would trap populations of energetic particles, i.e. cosmic rays. Cosmic rays with energies as high as 1e20 eV can be produced in violent environments associated with star-formation and AGN activities. Some of these cosmic rays would be injected into the vast intergalactic space, where clusters, super-clusters, filaments and void reside. While cosmic rays in galaxies and sub-galactic systems have been studied intensively over decades, cosmic rays in astrophysical environments above cluster scale have received very little attention. This talk will explore the various aspects of cosmic rays and their associated physics in large astrophysical structures, with focus on the hadronic processes and the "life journeys" of the most energetic particles. I will present some of the recent findings of my collaboration and will discuss why some of the standard approaches and ethodologies adopted for the studies of cosmic rays in galactic and sub-galactic systems could be inadequate
when investigating the cosmic rays in complex environments spanning across the top hierarchy of cosmological structures. I will present a more holistic, ecological approach that we have developed and some of the findings results from our work. More specifically, I will show how hadronic processes shape the life cycles of cosmic rays, some unusual phenomena occurring in the interfaces between systems in the hierarchy of cosmological structures, the fate of energetic cosmic-ray particles,
and the evolution of cosmic-ray contents in cosmological filaments and voids.
Language
演講語言 (Language): in English