Ionized outflows from active galactic nuclei as the essential elements of feedback

Outflows from active galactic nuclei (AGNs) are one of the fundamental mechanisms by which the central supermassive black hole interacts with its host galaxy. Detected in ≥50% of nearby AGNs, these outflows have been found to carry kinetic energy that is a large fraction of the AGN power, and thereby give `negative' feedback to their host galaxies. To understand the physical processes that regulate them, it is important to have a robust estimate of their physical and dynamical parameters. In this Review Article, we summarize our current understanding of the physics of the ionized outflows detected via absorption in the ultraviolet and X-ray wavelength bands. We discuss the most relevant observations and our current knowledge and uncertainties in the measurements of the outflow parameters, as well as their origin and acceleration mechanisms. The commissioning and concept studies of large telescope missions with high-resolution spectrographs in ultraviolet/optical and X-rays along with rapid advancements in simulations offer great promise for discoveries in this field over the next decade.