Speaker
Description
The gas cycle, comprising both inflow and outflow, is critical to galaxy evolution. Within this cycle, cold gas supplies raw material for star formation and black hole growth via inflow, and dominates the mass and energy of outflow. To investigate the role of cold gas cycle in galaxy evolution, we firstly collected a sample of gas-star misaligned galaxies from the MaNGA survey, which are believed to accrete gas from the environment. The interaction between pre-existing and accreted gas can consume angular momentum and trigger gas inflow. Applying the curve-of-growth method to quantify the HI profiles, we found that the cold HI gas in these misaligned galaxies is more centrally concentrated than their aligned controls. We also observed enhanced star formation in the center of star-forming misaligned galaxies. In a complementary study, we investigated the star formation driven cold molecular outflow in NGC 253 using the ALMA observation. We constrained the dense gas fraction with HCN/CO(1-0) ratio and the shock strength with SiO(2-1)/13CO(1-0) ratio. The elevated dense gas fraction and shock strength at the base of outflow streamers suggest that the star formation inside the giant molecular clouds can generate the shocks and further drive the molecular outflow.
