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The radius-luminosity (R-L) relationship of active galactic nuclei (AGNs) established by the reverberation mapping (RM) observations has been widely used as a single-epoch black hole mass estimator in the research of large AGN samples. However, the recent RM campaigns discovered that the AGNs with high accretion rates show shorter time lags by factors of a few comparing with the predictions from the R-L relationship. The explanation of the shortened time lags has not been finalized yet. We collect 8 different single-epoch spectral properties to investigate how the shortening of the time lags correlate with those properties and to understand what is the origin of the shortened lags. We find that the flux ratio between Fe II and H$beta$ emission lines shows the most prominent correlation, thus confirm that accretion rate is the main driver for the shortened lags. In addition, we establish a new scaling relation including the relative strength of Fe II emission. This new scaling relation can provide less biased estimates of the black hole mass and accretion rate from the single-epoch spectra of AGNs.
Black hole masses for samples of active galactic nuclei (AGN) are currently estimated from single-epoch optical spectra. In particular, the size of the broad-line emitting region needed to compute the black hole mass is derived from the optical or ul
We present an updated and revised analysis of the relationship between the Hbeta broad-line region (BLR) radius and the luminosity of the active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness decompositio
We reinvestigate the relationship between the characteristic broad-line region size (R_blr) and the Balmer emission-line, X-ray, UV, and optical continuum luminosities. Our study makes use of the best available determinations of R_blr for a large num
We present high-resolution HST images of all 35 AGNs with optical reverberation-mapping results, which we have modeled to create a nucleus-free image of each AGN host galaxy. From the nucleus-free images, we determine the host-galaxy contribution to
We have conducted a study to quantify the systematic differences resulting from using different stellar population models in optical spectroscopic identification of type II AGN. We examined the different AGN detection fractions of 7069 nearby galaxie