Speaker
Description
I will talk about the formation of exponential star-forming disk and the corresponding metal enrichment in the modified accretion disk (MAD) framework. The MAD is suggested by the recent simulations that coplanar gas inflow mainly provides the fuel of star formation. We treat the galactic gas disk as a simple gas-regulator system that the SFR is instantaneously determined by the gas content, which is regulated by the interplay between inflow, outflow and star formation. Based on this simple model, we can obtain the analytic solution of radial profile of the gas-phase metallicity, which well characterises the overall features of the observed ones. The negative gradient of gas-phase metallicity is a natural consequence of the radial inflow of cold gas which is continuously enriched by in-situ star formation. We also show that magnetic stresses from magneto-rotational instability are the most plausible source of the required viscosity that sustains the exponential star-forming disk.
