Shanghai Astronomical Observatory Astrophysics Colloquium

Title : The Origin of Galactic Cosmic Rays

Speaker: Prof. Siming Liu (Southwest Jiaotong University)

Time：3:00 pm Dec.25th (Thursday)

Tencent Meeting：46822606747, password: 6360

Location: Lecture Hall, 3rd floor

Abstract：

Since the discovery of cosmic rays in 1912, its origin has been a topic of persistent interests in both the science community and the general public. Besides driving the development of the standard model of particle physics during the first half-a-century of its discovery before the construction of powerful accelerators, researches on cosmic rays have shown that they dominate the synthesis of beryllium and boron elements in the universe, control the abundance of radioactive elements in the atmosphere, and may play a role in regulating the climate. In this talk, I will focus on origin of cosmic rays with an energy up to PeV. Precise measurement of cosmic ray spectra, in combination with advances in gamma-ray astronomy, during the past two decades, have made it possible to address the origin of cosmic rays quantitatively. In particular, the standard paradigm that low energy (GeV to TeV) cosmic rays are mostly accelerated by shocks of supernova remnants remains valid. PeV cosmic rays, however, are likely accelerated by processes beyond the classical diffusive shock acceleration mechanism.

CV：

Siming Liu is a professor at the school of physical science and technology, Southwest Jiaotong University. He has been mostly working acceleration and radiation of high-energy particles in the Universe. Since obtained a PhD in physics from the University of Arizona working on accretion of supermassive black holes in 2002, he has carried out researches at Stanford University, Los Alamos National Laboratory, University of Glasgow, Purple Mountain Observatory on varieties of high energy phenomena, including solar flares, active galactic nuclei, supernova remnants, pulsar wind nebulae. He joined the Southwest Jiaotong University in 2021 and has been the leader of the particle astrophysics group.  

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