The Study Of AGN Feedback And Outflow

M-σ and MBH-M_bulge relationship indicate that black hole and galaxies are coevolving. Through the study of quasar, people find M-σ relationship still holds for quasars. This shows the AGN activity and star-forming activity are linked. The details of how they linked is unclear. Some authors think gas losses angular momentum due to galaxy interaction, and gas falls to the nuclei. Star-burst activity and AGN activity are then triggered, and the AGN activity feedback on the star-formation, suppress the star-formation by ejecting large amount of energy into the gas, quenching its cooling. This feedback process also acts to quench black hole accretion. The feedback gives rise to some link between accretion rate of black hole and star-formation rate. Meanwhile, how the energy is released and how efficient it influences the surrounding gas are crucial to our understanding of this process.Outflows are the carrier of AGN feedback. We find that the quasars with strong outflows have enhanced infrared emission through studying a sample of z-2quasars. This could be either a large amount of hot dust is embedded in the outflow or the outflow interact with the surrounding gas that produces the excess IR emission. Physically, high speed outflow can blow away cold gas clouds through the viscosity of the wind. The outflow produced by quasars may drive away the cold gas in the host galaxy so that suppresses the star formation.A key point to study of AGN-Starformation relationship is how to determine the relative time interval between these two activities. E+A galaxy have ever experienced a recent star-burst activity and their star-formation were truncated recently. We construct a sample of strong-H5absorption AGNs. We found that these galaxies have quite similar star formation history to the E+A galaxies. This type of galaxies might be good time candidates to study the relationship between AGN and star-burst activity.