Far-Ultraviolet Spectra of AGN: First Results from FUSE

Composite spectra derived from HST observations of moderate redshift (z ∼ 1) quasars show that the peak of the spectral energy distribution is at ∼1000 Å, and that the ionizing continuum falls off smoothly to shorter wavelengths as fν ∼ ν −1.8. HUT and FUSE observations of nearby AGN (e.g., 3C 273) show similar results. FUSE spectra reveal a wealth of detail in the 912–1200 Å spectral range, including multi-component intrinsic absorption in the O vi doublet and Lyβ, and surprisingly strong narrow-line emission from O vi λλ1032, 1038. Monitoring observations of AGN below 1200 Å are feasible, and such experiments could help to unravel the structure of intrinsic absorbers in AGN as well as the highest ionization portions of the broad-line region.