Shanghai Astronomical Observatory Astrophysics Colloquium

Title：Radiation and Variability of Active Galactic Nuclei

Speaker：Zhen-Yi Cai (USTC)

Time：3:00 pm May 30th (Thursday)

Tencent Meeting：42915400486 password: 6360

Location: Lecture Hall, 3rd floor

Abstract：

Active Galactic Nuclei (AGNs) feature gas swirling towards a supermassive black hole (BH) inhabiting a galactic center. This "BH-accretion" paradigm, involving cold disk and hot corona, is believed to be the central engine for AGNs. The cold disk produces enormous amounts of radiation from optical to ultraviolet wavelengths, while the hot corona is responsible for the X-ray emission. Moreover, the optical to X-ray radiation is variable and there are complex relationships, e.g., co-ordination and time delay, among multi-band variations. However, both the multi-wavelength (e.g., extreme ultraviolet in particular) radiation properties and the variability origin of AGNs have not been fully understood yet. In this talk, I should review the current status of our knowledge on radiation and variability of AGNs and mainly introduce what I have learned over the past decade.

CV：Zhen-Yi Cai obtained his BS in physics from Xiamen University (XMU) in 2007, and his PhD in astrophysics in 2013 through a joint PhD project between XMU and SISSA (Italy). From 2014 to 2020, he was a postdoctoral fellow and then an associate researcher in the Department of Astronomy at the University of Science and Technology of China (USTC). Since April 2020, he is an associate professor at USTC. Currently, his main research interest is the variability of active galactic nuclei.

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