Magnetic field is one of the most important physical quantities regulating the evolution of interstellar medium and star formation in the Milky Way. Despite enormous surveys using techniques of dust polarization, Faraday rotation, and synchrotron polarization to reveal the magnetic field structure of the Milky Way, none of the techniques can give accurate magnetic field strength. Zeeman effect is the only method to directly measure interstellar magnetic field strength, but large-scale mapping of Zeeman effect is still not available due to the lack of high-sensitive and well-calibrated telescope. Recently, I finished the polarization commissioning of the FAST 19-beam receiver, and the efficiency of FAST Zeeman observations hence increases by an order of magnitude than the previous telescopes. The FAST observations of HI emission and HI narrow self-absorption Zeeman measurements offer critical evidence addressing the classical magnetic flux problem in star formation. I am currently a Jansky fellow leading a VLA Zeeman project and actively participating ngVLA. I plan to apply the technique of Zeeman observations to the large projects of FAST, FASTA, and SKA to produce the first map of interstellar magnetic field strength at galactic scale.
Tao-Chung Ching (庆道冲) is a Jansky fellow in the National Radio Astronomy Observatory. He received his PhD in 2017 from the Institute of Astronomy in the National Tsing-Hua University, Taiwan. During his graduated study, he was also a Predoctoral Fellow of the Harvard-Smithsonian Center for Astrophysics from 2013 to 2015. He worked in National Astronomical Observatories, Chinese Academy of Sciences (NAOC) as a FAST Postdoctoral Fellow from 2017 to 2019 and as a Chinese Academy of Sciences Fellow of Taiwanese Young Talented Scholar from 2019 to early 2022. He later became a research fellow in the Research Institute of Intelligent Computing, Zhejiang Lab. He joined the National Radio Astronomy Observatory since September 2022. He was the first author of a Nature cover article and a major collaborator of a Nature Communication article. His research interests are interstellar magnetic fields and star formation through observations from submillimeter to radio wavelengths with single-dish and interferometric telescopes.
Host: Xuening Bai