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

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 less than or similar to 1 day. The broad Ha and HE emission lines respond to similar to 35% ultraviolet continuum variations with an amplitude of similar to 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 similar to 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 similar to 10(6)-10(7) M-.. Concomitantly, we find evidence for wavelength-dependent continuum time delays: optical continuum variations lag those at 1315 Angstrom by 1.0 +/- 0.3 days at 4865 Angstrom to 1.5 +/- 0.7 days at 6962 Angstrom. This suggests a stratified continuum reprocessing region extending several light days from the central source, possibly an accretion disk.</p

Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. XVI. A 13 year study of spectral variability in NGC 5548

We present the final installment of an intensive 13 year study of variations of the optical continuum and broad Hbeta emission line in the Seyfert 1 galaxy NGC 5548. The database consists of 1530 optical continuum measurements and 1248 Hbeta measurements. The Hbeta variations follow the continuum variations closely, with a typical time delay of about 20 days. However, a year-by-year analysis shows that the magnitude of emission-line time delay is correlated with the mean continuum flux. We argue that the data are consistent with the simple model prediction between the size of the broad-line region and the ionizing luminosity, rproportional toL(ion)(1/2). Moreover, the apparently linear nature of the correlation between the Hbeta response time and the nonstellar optical continuum F-opt arises as a consequence of the changing shape of the continuum as it varies, specifically F(opt)proportional toF(UV)(0.56).