Lunch talk on Apr. 1, 2024

Exploring the Supermassive Black Hole at the Galactic Center and the Star Formation History in its Environment

Speaker: Zhuo Chen (University of Washington)

Venue: Video Conference

Time: 12:30 PM, Monday, Apr. 1, 2024

Abstract: 

As the closest galactic nucleus, the Galactic center provides a unique opportunity for learning about the supermassive black hole at the center of the Milky Way, Sgr A*, and the composition and formation of the stellar population in this extreme environment. In this talk I will present the investigation of the long-term near-infrared accretion properties of Sgr A* with the longest time baseline yet considered. I will then introduce a new window on the star formation history at the Galactic center. The limitation in our current understanding of the nuclear star cluster (NSC) star formation history is that previous studies assumed that all stars have solar metallicity. However, age and metallicity are degenerate parameters in star formation histories; by ignoring the effect of metallicities, the age estimates can be biased. Recent spectroscopic surveys showed a significant spread in the metallicity of stars in the NSC, which motivates us to revisit the star formation history and its implications on the formation and evolution of the NSC. In this talk I will present NSC star formation history for the first time with metallicity constraints as obtained from a large sample of stellar metallicity measurements from Gemini and the Very Large Telescope. The analysis shows significantly different star formation history than any previously published works. In addition, we test different initial mass functions, and present more accurate estimates on the number of compact objects and black hole-black hole merger rates at the Galactic center.

Report PPT:  SWIFAR_Zhuo Chen.pdf