Steps toward Determination of the Size and Structure of the Broad‐Line Region in Active Galactic Nuclei. XIV. Intensive Optical Spectrophotometric Observations of NGC 7469

Abstract

We present results of an intensive 2 month campaign of ground-based spectrophotometric monitoring of the Seyfert 1 galaxy NGC 7469, with a temporal resolution ≲ 1 day. The broad Hα and Hβ emission lines respond to ~35% ultraviolet continuum variations with an amplitude of ~10% and time delays of 5.6 ± 1.3 days and 5.4 ± 0.8 days, respectively. We interpret this as evidence of variable Balmer line gas ~5-6 light days from the central source in this object, widely believed to be a supermassive black hole. The virial mass of the central source implied by line widths and time delays is ~106-107 M☉. Concomitantly, we find evidence for wavelength-dependent continuum time delays: optical continuum variations lag those at 1315 Å by 1.0 ± 0.3 days at 4865 Å to 1.5 ± 0.7 days at 6962 Å. This suggests a stratified continuum reprocessing region extending several light days from the central source, possibly an accretion disk.