Quasar Outflows: Regulating Galaxy Evolution and Feedback Mechanisms

Quasar outflows, including broad absorption lines (BALs), play a significant role in regulating the coevolution between supermassive black holes (SMBHs) and their host galaxies, as well as establishing correlations between SMBH mass and properties of the surrounding bulge. These outflows, which indicate the existence of gas outflows, are also considered as potential candidates for active galactic nuclei (AGN) feedback processes, including terminating star formation in the interstellar medium (ISM) and regulating accretion onto the SMBHs. The presence of blueshifted absorption troughs with large outward velocities in quasar spectra provides direct observational evidence for gaseous outflows and supports the notion of feedback mechanisms from central engines to regulate star formation in host galaxies.