A high signal-to-noise ultraviolet spectrum of NGC 7469: New support for reprocessing of continuum radiation

From 1996 June 10 to 1996 July 29, the International AGN Watch monitored th e Seyfert I galaxy NGC 7469 using the International Ultraviolet Explorer, t he Rossi X-Ray Timing Explorer, and a network of ground-based observatories . On 1996 June 18, in the midst of this intensive monitoring period, we obt ained a high signal-to-noise snapshot of the UV spectrum from 1150 to 3300 Angstrom using the Faint Object Spectrograph (FOS) on the Hubble Space Tele scope. This spectrum allows us to disentangle the UV continuum more accurat ely from the broad wings of the emission lines, to identify clean continuum windows free of contaminating emission and absorption, and to deblend line complexes such as Ly alpha + N V, C IV + He II + O III], Si III] + C III], and Mg II + Fe II. Using the FOS spectrum as a template, are have fitted a nd extracted line and continuum fluxes from the IUE monitoring data. The cl eaner continuum extractions confirm the discovery of time delays between th e different UV continuum bands by Wanders et al. Our new measurements show delays increasing with wavelength for continuum bands centered at 1485, 174 0, and 1825 Angstrom relative to 1315 Angstrom with delays of 0.09, 0.28, a nd 0.36 days, respectively. Like many other Seyfert 1 galaxies, the UV spec trum of NGC 7469 shows intrinsic, blueshifted absorption in Ly alpha, N V, and C IV. Soft X-ray absorption is also visible in archival ASCA X-ray spec tra. The strength of the UV absorption, however, is not compatible with a s ingle-zone model in which the same material absorbs both the UV and X-ray l ight. Similar to other Seyfert galaxies, such as NGC 3516, the UV-absorbing gas in NGC 7469 has a lower ionization parameter and column density than t he X-ray-absorbing material. While the UV and X-ray absorption does not ari se in the same material, the frequent occurrence of both associated UV abso rption and X-ray warm absorbers in the same galaxies suggests that the gas supply for each has a common origin.