2020年7月24日, 星期五

Astronomy Colloquium (06.02/2020): Spin Evolution of Massive Black Holes in Galactic Centers

06.02.2020 12:45 pm - 1:45 pm


Meeting ID: 523 477 035
Joining Link:
Speaker:Prof. Youjun Lu, NAOC

Prof. Youjun Lu got his PhD from USTC in 1997 and subsequently spent ~10 years working at various leading institutes in north America including Princeton, CITA, UC Berkeley and UCSC, before joining NAOC as a professor in 2014. He is now leading the gravitational wave astrophysics group at NAOC. Prof. Lu's research covers many theoretical astrophysics fields, including black holes, gravitational wave, high energy astrophysics, dynamics, galaxies and cosmology.

Abstract:Massive Black Holes (MBHs) in galactic centers are believed to be described by the Kerr metric with only two parameters (mass and spin; no-hair theorem). The distribution of those MBHs on the mass and spin plane contains rich information on the MBH growth history. In this talk, I will report our recent investigations on the spin evolution of MBHs under various accretion processes. We show that different accretion modes (e.g., coherent, chaotic, or tidal star accretion) result in quite different spin distribution. Assuming a two phase accretion model, an initial coherent accretion followed by a later chaotic accretion phase, we use the current available spin measurements to obtain constraints on the MBH growth history and discuss future prospects for such constraints . I will also talk about the possible correlation between the radiative efficiency of QSOs and the MBH mass.
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