Multiwavelength studies of the Seyfert 1 galaxy NGC7469. I - Far UV observations with FUSE

We obtained far-ultraviolet spectra of the Seyfert 1 galaxy NGC 7469 using the Far Ultraviolet Spectroscopic Explorer on 1999 December 6. Our spectra cover the wavelength range 990–1187 Å with a resolution of ∼ 0.05 Å. We see broad emission lines of C III, N III, O VI, and He II as well as intrinsic absorption lines in the O VI λλ1032, 1038 resonance doublet. The absorption arises in two distinct kinematic components at systemic velocities of−569 km s−1 and −1898 km s−1. Both components are very highly ionized—no significant Lyβ absorption is present. The higher blueshift component is not quite saturated, and it has a total O VI column density of 8× 10 cm−2. It covers more than 90% of the continuum and broad-line emission. The lower blueshift component is heavily saturated and covers only ∼ 50% of the continuum and broadline emission. It too has a column density of 8 × 10 cm−2, but this is less certain due to the high saturation. We set an upper limit of < 1.5 × 10 cm−2 on the O VI column density of this component. Its line depth is consistent with coverage of only the continuum, and thus this component may lie interior to the broad emission-line gas. The component at −569 km s−1 has a velocity comparable to the high-ionization X-ray absorption lines seen in the XMM-Newton grating spectrum of NGC 7469, and photoionization models show that the observed column densities of O VI and H I are compatible with their formation in the same gas as that causing the X-ray absorption. The gas at−1898 km s−1 has lower ionization and column density, and no significant X-ray absorption is associated with it.