HST/COS Observations of Quasar Outflows in the 500-1050 Å Rest Frame. I. The Most Energetic Outflows in the Universe and Other Discoveries

The Hubble Space Telescope/Cosmic Origins Spectrograph (COS) has opened a new discovery space for studying quasar absorption outflows and their contribution to active galactic nucleus (AGN) feedback. Specifically, COS provides high-quality far-ultraviolet (FUV) spectra covering the diagnostic-rich 500-1050 Å rest frame (hereafter, EUV500) of medium redshift objects. The quality and quantity of EUV500 diagnostic troughs allow us to probe the very high-ionization phase, which carries 90% or more of the outflowing material, as well as to determine the distance of most outflows from the central source (R). The first objective is impossible to achieve with ground-based spectra, and R can be measured in only ∼1% of them. Here, we summarize the main results of the first dedicated survey of such outflows, including the following.