We compile a sample consisting of 56 radio-quiet active galactic nuclei so as to investigate statistical properties of hot corona of accretion disks from ASCA observations. The black-hole masses in the sample are estimated via several popular methods and the bolometric luminosities from the multi-wavelength continuum. This allows us to estimate the Eddington ratio (E ≡ L Bol /L Edd ) so that the undergoing physical processes can be tested via hard X-ray data. We find a strong correlation between F X ≡ L 2−10keV /L Bol and E as F X ∝ E −0.64 with a multivariate regression. This indicates that the release of gravitational energy in the hot corona is controlled by the Eddington ratio. On the other hand, the correlation between the hard X-ray spectral index (Γ) and E depends critically on the types of objects: Γ is nearly constant (Γ ∝ E 0 ) in broad-line Seyfert 1's (BLS1s), whereas Γ ∝ log E 0.18 in narrow-line Seyfert 1's (NLS1s), although not very significant. We can set constraints on the forms of magnetic stress tensor on the condition that F X is proportional to the fraction f of gravitational energy dissipated in the hot corona and that f is proportional to magnetic energy density in the disk. We find that the shear stress tensor t rφ ∝ P gas is favored by the correlation in the present sample, where P gas is the gas pressure.

The radius-luminosity (R Hβ -L 5100 ) 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 Hβ -L 5100 relationship. The explanation of the shortened time lags has not been finalized yet. We collect 8 different singleepoch 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 Hβ 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.

This is the third in a series of papers reporting on a large reverberation-mapping campaign aimed to study the properties of active galactic nuclei (AGNs) with high accretion rates. We present new results on the variability of the optical Fe II emission lines in 10 AGNs observed by the Yunnan Observatory 2.4 m telescope from2012 to2013. We detect statistically significant timelags, relative to the AGN continuum, in nine of the sources. This accurate measurement is achieved using a sophisticated spectral fitting scheme that allows for apparent flux variations of the host galaxy, and several narrowlines, due to the changing observing conditions. Six of the newly detected lags are indistinguishable from the Hβ lags measured in the same sources. Two are significantly longer and one is slightly shorter. Combining these findings with the Fe II lags reported in previous studies, we find an Fe II radius-luminosity relationship similar to the one for Hβ, although our sample by itself shows no clear correlation. The results support the idea that Fe II emission lines originate in photoionized gas, which, for the majority of the newly reported objects, is indistinguishable from the Hβ-emitting gas. We also present a tentative correlation between the lag and intensity of Fe II and Hβ and comment on its possible origin.

The properties of relativistic radio jets are thought to be closely connected with the properties of accretion disks in active galactic nuclei. We explore this issue using a sample of 35 blazars with very long baseline observations, for which we can estimate the kinetic powers of their relativistic jets, the bolometric luminosity of their accretion disks, and the masses of their black holes. Contrary to previous claims, we find that the jet kinetic power is significantly correlated with the disk luminosity. This supports the notion that the disk is somehow coupled to the jet, even on parsec scales. Moreover, we show that the correlation improves by including the black hole mass as a second parameter. The dominance of the jet, parameterized as the ratio of the jet kinetic power to the disk luminosity, is largely controlled by and is inversely correlated with the Eddington ratio of the accretion disk. This empirical relation should serve as a useful guide for theoretical models for jet formation.

This is the second in a series of papers reporting on a large reverberation mapping (RM) campaign to measure black hole (BH) mass in high accretion rate active galactic nuclei (AGNs). The goal is to identify super-Eddington accreting massive black holes (SEAMBHs) and to use their unique properties to construct a new method for measuring cosmological distances. Based on theoretical models, the saturated bolometric luminosity of such sources is proportional to the BH mass which can be used to obtain their distance. Here we report on five new RM measurements and show that in four of the cases we can measure the BH mass and three of these sources are SEAMBHs. Together with the three sources from our earlier work, we now have six new sources of this type. We use a novel method based on a minimal radiation efficiency to identify nine additional SEAMBHs from earlier RM-based mass measurements. We use a Bayesian analysis to determine the parameters of the new distance expression, and the method uncertainties, from the observed properties of the objects in the sample. The ratio of the newly measured distances to the standard cosmological ones has a mean scatter of 0.14 dex, indicating that SEAMBHs can be use as cosmological distance probes. With their high luminosity, long period of activity and large numbers at high redshifts, SEAMBHs have a potential to extend the cosmic distance ladder beyond the range now explored by type Ia supernovae.

Double-peaked [O III] profiles in active galactic nuclei (AGNs) may provide evidence for the existence of dual AGNs, but a good diagnostic for selecting them is currently lacking. Starting from ∼ 7000 active galaxies in SDSS DR7, we assemble a sample of 87 type 2 AGNs with double-peaked [O III] profiles. The nuclear obscuration in the type 2 AGNs allows us to determine redshifts of host galaxies through stellar absorption lines. We typically find that one peak is redshifted and another is blueshifted relative to the host galaxy. We find a strong correlation between the ratios of the shifts and the double peak fluxes. The correlation can be naturally explained by the Keplerian relation predicted by models of co-rotating dual AGNs. The current sample statistically favors that most of the [O III] double-peaked sources are dual AGNs and disfavors other explanations, such as rotating disk and outflows. These dual AGNs have a separation distance at ∼ 1 kpc scale, showing an intermediate phase of merging systems. The appearance of dual AGNs is about ∼ 10 −2 , impacting on the current observational deficit of binary supermassive black holes with a probability of ∼ 10 −4 (Boroson & Lauer).

Supermassive black holes in active galactic nuclei (AGNs) undergo a wide range of accretion rates, which lead to diversity of appearance. We consider the effects of anisotropic radiation from accretion disks on the broad-line region (BLR), from the Shakura-Sunyaev regime to slim disks with super-Eddington accretion rates. The geometrically thick funnel of the inner region of slim disks produces strong self-shadowing effects that lead to very strong anisotropy of the radiation field. We demonstrate that the degree of anisotropy of the radiation fields grows with increasing accretion rate. As a result of this anisotropy, BLR clouds receive different spectral energy distributions depending on their location relative to the disk, resulting in diverse observational appearance of the BLR. We show that the self-shadowing of the inner parts of the disk naturally produces two dynamically distinct regions of the BLR, depending on accretion rate. These two regions manifest themselves as kinematically distinct components of the broad Hβ line profile with different line widths and fluxes, which jointly account for the Lorentzian profile generally observed in narrow-line Seyfert 1 galaxies. In the time domain, these two components are expected reverberate with different time lags with respect to the varying ionizing continuum, depending on the accretion rate and the viewing angle of the observer. The diverse appearance of the BLR due to the anisotropic ionizing energy source can be tested by reverberation mapping of Hβ and other broad emission lines (e.g., Fe II), providing a new tool to diagnose the structure and dynamics of the BLR. Other observational consequences of our model are also explored.

Broad emission lines in active galactic nuclei (AGNs) mainly arise from gas photoionized by continuum radiation from an accretion disk around a central black hole. The shape of the broad-line profile, described by D Hβ = FWHM/σ Hβ , the ratio of full width at half maximum to the dispersion of broad Hβ, reflects the dynamics of the broad-line region (BLR) and correlates with the dimensionless accretion rate (Ṁ ) or Eddington ratio (L bol /L Edd ). At the same time,Ṁ and L bol /L Edd correlate with R Fe , the ratio of optical Fe II to Hβ line flux emission. Assembling all AGNs with reverberation mapping measurements of broad Hβ, both from the literature and from new observations reported here, we find a strong bivariate correlation of the form log(Ṁ , L bol /L Edd ) = α + βD Hβ + γR Fe , where α = (2.47, 0.31), β = −(1.59, 0.82) and γ = (1.34, 0.80). We refer to this as the fundamental plane of the BLR. We apply the plane to a sample of z < 0.8 quasars to demonstrate the prevalence of super-Eddington accreting AGNs are quite common at low redshifts.