No abstract

We present the final results from a high sampling rate, multi-month, spectrophotometric reverberation mapping campaign undertaken to obtain either new or improved Hβ reverberation lag measurements for several relatively low-luminosity active galactic nuclei (AGNs). We have reliably measured the time delay between variations in the continuum and Hβ emission line in six local Seyfert 1 galaxies. These measurements are used to calculate the mass of the supermassive black hole at the center of each of these AGNs. We place our results in context to the most current calibration of the broad-line region (BLR) R BLR -L relationship, where our results remove outliers and reduce the scatter at the low-luminosity end of this relationship. We also present velocity-resolved Hβ time-delay measurements for our complete sample, though the clearest velocity-resolved kinematic signatures have already been published.

We present extinction curves derived from the broad emission lines and continua of samples of 72 radio-loud and 1018 radio-quiet AGNs. The curves are significantly flatter in the UV than are curves for the local ISM. The reddening curves for the radio-quiet LBQS quasars are slightly steeper than those of the radio-loud quasars in the UV, probably because of additional reddening by dust further out in the host galaxies of the former. The UV extinction curves for the radio-loud AGNs are very flat. This is explicable with slight modifications to standard MRN dust models: there is a relative lack of small grains in the nuclear dust. Our continuum and broad-emission line reddening curves agree in both shape and amplitude, confirming that the continuum shape is indeed profoundly affected by reddening for all but the bluest AGNs. With correction by our generic extinction curve, all of the radio-loud AGNs have continuous optical-UV spectra consistent with a single shape. We show that radio-quiet AGNs have very similar intrinsic UV to optical shape over orders of magnitude in luminosity. We also argue that radio-loud and radio-quiet AGNs probably share the same underlying continuum shape and that most of the systematic differences between their observed continuum shapes are due to higher nuclear reddening in radio-selected AGNs, and additional reddening from dust further out in the host galaxies in radio-quiet AGNs. Our conclusions have important implications for the modelling of quasar continua and the analysis of quasar demographics.

I review progress made in understanding the nature of the broad-line region (BLR) of active galactic nuclei (AGNs) and the role BLRs play in the AGN phenomenon. The high equivalent widths of the lines imply a high BLR covering factor, and the absence of clear evidence for absorption by the BLR means that the BLR has a flattened distribution and that we always view it near pole-on. The BLR gas is strongly self-shielding near the equatorial plane. Velocity-resolved reverberation mapping has long strongly excluded significant outflow of the BLR and shows instead that the predominant motions are Keplerian with large turbulence and a significant net inflow. The rotation and turbulence are consistent with the inferred geometry. The blueshifting of high-ionization lines is a consequence of scattering off inflowing material rather than the result of an outflowing wind. The rate of inflow of the BLR is sufficient to provide the accretion rate needed to power the AGN. Because the motions of the BLR are gravitationally dominated, and the BLR structure is very similar in most AGNs, consistent black hole masses can be determined. The good correlation between these estimates and masses predicted from the bulge luminosities of host galaxies provides strong support for the similarity of AGN continuum shapes and the correctness of the BLR picture presented. It is concluded that although many mysteries remain about the details of how AGNs work, a general overall picture of the torus and BLR is becoming clear.Comment: Invited review given at 7th Serbian Conference on Spectral Line Shapes, Zrenjanin, Serbia, 15-19 June 2009. New Astronomy Reviews in press. 12 pages. 14 figures (some look best in color). Some additional references and discussion adde

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 day. The broad Ha and Hb emission [ 1 lines respond to D35% ultraviolet continuum variations with an amplitude of D10% 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 D5È6 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 D106È107 Concomi-M _. tantly, we Ðnd evidence for wavelength-dependent continuum time delays : optical continuum variations lag those at 1315 by 1.0^0.3 days at 4865 to 1.5^0.7 days at 6962 This suggests a stratiÐed A A A. continuum reprocessing region extending several light days from the central source, possibly an accretion disk.