Colloquium on Sep. 7, 2023

Understanding the galaxy formation and metal-enrichment in the view of gas-regulator framework

Speaker:Enci Wang (USTC)

Venue:SWIFAR Building 2111

Time:16:00 PM, Thursday, Sep. 7, 2023

Abstract:

Star-forming galaxies are actively accreting gas from surrounding materials during the cosmic time, while the feedback from star formation on the other hand blows the gas away as well as enriches the inter-stellar/-galactic medium. The interplay between inflow, outflow and star formation is then the key to understand the formation and evolution of star-forming galaxies, as well as the relevant observational facts. Under this point of view, we propose the idea of using the time-variability to understand the dispersion of star formation rate (SFR) and metallicity within and across galaxies. This idea is directly verified from the observation, which opens the time-dimension to study galaxy formation and evolution. Based on the continuity equations, we construct a theoretical frame of the coevolution between star formation, chemical enrichment and cold gas content. This frame explains many observational facts, revealing that the dispersion in SFR and metallicity is driven by time-varying inflow rate at galactic scale. In addition, we also construct a leaky accretion disk model to describe the formation of gas disk in galaxies. This model quantitatively explains the radial gradient of gas-phase metallicity, and uncovers that the origin of the exponential star-forming disk is the viscous process induced by magneto-rotational instability.

Report PPT:SWIFAR_Enci Wang.pdf