FUSE Observations of Active Galactic Nuclei and Prospects for the Future

Abstract

Over its 8‐year lifetime, the Far Ultraviolet Spectroscopic Explorer observed over 200 hundred active galactic nuclei (AGN). Many of these observations were campaigns dedicated to AGN science, including coordinated observations with other observatories such as Chandra, XMM‐Newton, and the Hubble Space Telescope. However, most observations were part of large samples of nearby AGN that served as background probes of gas in the interstellar medium, the Galactic halo and the local intergalactic medium. These large samples and the dedicated campaigns have broadly advanced our understanding of the far‐ultraviolet continuum of AGN and the ubiquitous outflows of photoionized gas from their active nuclei. The bright, nearby, lower‐luminosity AGN observed with FUSE generally have bluer continua than their higher luminosity counterparts observed with HST, and the spectral shapes are broadly consistent with accretion disk models. More than half of the Type 1 AGN observed with FUSE show blueshifted intrinsic absorption by the O VI doublet, indicative of highly ionized outflows from the central nuclear regions. I will give an overview of these observations, and interpret them in the context of winds from accretion disks and thermally driven winds originating from the obscuring torus, with an eye toward what observational capabilities are needed in the future to understand the role of outflows in the structure and evolution of AGN, and their impact on their environments.