The fundamental role of black holes in regulating how galaxies grow and die over cosmic time

Almost every massive galaxy contains a supermassive black hole (BH) at its center. For decades, both theory and numerical simulations have suggested that BHs play a central role in regulating the growth and quenching of galaxies. In particular, BH feedback by heating or blowing out the interstellar or circumgalactic medium (ISM and CGM) forms the basis of current models of massive galaxy formation. However, observationally it remains unclear whether and how BHs influence the global ISM and CGM in general galaxies. In this talk , I will first present our recent findings that BH masses serve as the fundamental driver of the atomic hydrogen (HI) content  in nearby galaxies, with galaxies hosting more massive BHs having lower HI gas content. This provides critical evidence that the accumulated energy from BH accretion affects the cooling of galaxy-wide ISM and CGM, which will eventually quench galaxies. I will then move on to the early Universe, and discuss how different galaxy populations, including the earliest quasars at cosmic dawn and massive galaxies at cosmic noon, may also fit into the same picture:  galaxies with more massive BHs may consume their gas faster and be quenched earlier than systems with lower-mass BHs.

Fangzhou Jiang
Thursday, March 21, 2024 - 3:30PM to Thursday, March 21, 2024 - 4:30PM
Tao Wang is a professor of Astronomy at the School of Astronomy and Space Science, Nanjing University. He received his Ph.D. degree from Nanjing University in 2012. He was a postdoctoral fellow at CEA-Saclay, France, from 2013 to 2016, and at Tokyo University, Japan, from 2017 to 2020. He joined Nanjing University in 2021. His main research focuses on the formation and evolution of galaxies and galaxy clusters over cosmic time, using multi-wavelength observations from the world's most powerful optical, submillimeter, and radio telescopes.