【T. D. Lee Colloquium No. 17】Explore the Time Frontier: from Galileo to Cosmic Antennae
by
S500 Lecture Hall
Human's perception and philosophy of the cosmos depend on our collective sensors. Modern optical sky surveys in the 20th century gave rise to the concept of dynamic Universe, the forefront of which currently lies in radio bands and manifests itself as fast radio bursts (FRB). FRB researches have been awarded the 2023 Shaw prize and the 2024 Marcel Grossman Award. We built the largest radio telescope, namely, the Five-hundred-meter Aperture Spherical radio Telescope (FAST), which has been leading the field of characterizing repeating FRBs ever since the its inception in 2020. With close to 100 FAST-based papers on FRBs, including 5 on Nature and 2 on Science, we started to establish an evolutionary picture for FRBs. With compact objects being the leading candidate engine of FRBs, the lack of short-time-scale periodicity present a major mystery regarding FRBs' origin. Recently, we invented the Pincus-Lyapunov diagram to help ascertain the stochastic nature of FRBs. The P-L diagram quantify FRBs to be less chaotic than Earthquakes, but way more random, akin to a Brownian motion on the energy-time bi-variate space. This stochastic behavior presumably reflects the young ages of FRBs. To help systematically localize and discover multi-band counterparts, we are building a next generation FRB machine, namely Cosmic Antennae (CA), the aim of which is to increase the discovery rate by orders of magnitude over all current radio telescopes.
Dr. Di Li is a radio astronomer. He was the Chief Scientist of FAST and is now a chair professor of Tsinghua University. He pioneered several observing techniques, including HI narrow self-absorption (HINSA), based on which a precise measurement of interstellar magnetic field was obtained and published on the cover of Nature. Dr. Li has led multiple discoveries, including the first detection of interstellar molecular oxygen, the largest set of fast radio burst (FRB) events, the first persistently active FRB, etc. He has published more than 300 peer-reviewed journal articles, including 6 on Nature and 2 on Science. Dr. Li won numerous awards, including the 2022 Distinguished Achievement Award of the Chinese Academy of Sciences (CAS) as the PI, the 3rd national Innovation Award in 2023. and the 2024 Marcel Grossmann award. He took on leading roles in national and international organizations, including the Steering Committee of Australia Telescope National Facility (ATNF), the SEAC of SKA, the advisory panel of the Breakthrough Listen initiative.
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