Research Progress on Velocity Shifts of Quasar Absorption Lines postprint

Abstract: Outflows serve as a crucial feedback mechanism in quasars, playing a significant role in understanding the co-evolution processes between quasars and their host galaxies. This paper collects and organizes literature on the research of velocity shifts in outflow ab#2;sorption lines, compares and analyzes the identification methods, challenges, and generation mechanisms of such velocity shifts, and discusses potential future research directions. While current empirical cases of absorption line velocity shifts are limited and their underlying physical mechanisms remain unclear, the growth of quasar survey data and advancements in data processing techniques are expected to lead to breakthroughs in this field, such progress will not only deepen our understanding of quasar outflows, but also offer new perspectives for galaxy evolution studies.