Six z~2-3 quasars with extreme LoBAL outflows and weak UV lines are interpreted as weak-emission-line quasars emerging from dust cocoons via disc winds that shatter grains and produce steeper extinction.
Reverberation Measurements for 17 Quasars and the Size-Mass-Luminosity Relations in Active Galactic Nuclei
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abstract
(abridged) We have spectrophotometrically monitored a well-defined sample of 28 Palomar-Green quasars in order to obtain measurements of their BLRs and to investigate the relationships between quasar luminosity, central black hole mass, and broad emission line region (BLR) size in active galactic nuclei (AGN). Spectrophotometry was obtained every 1-4 months for 7.5 years, yielding 20-70 observing epochs per object. Both the continuum and emission line fluxes of all of the quasars were observed to change during the duration of the observing program. Seventeen of the 28 objects were observed with adequate sampling to search for correlated variations between the Balmer emission lines and the continuum flux. For each of these 17 objects, a significant correlation was observed, with the Balmer line variations lagging those of the continuum by \~100 days (rest frame). Our work increases the available luminosity range for studying the size-mass-luminosity relations in AGN by two orders of magnitude and doubles the number of objects suitable for such studies. Combining our results with comparable published data available for Seyfert 1 galaxies, we find the BLR size scales with the rest-frame 5100 A luminosity as L^{0.70+-0.03}. This determination of the scaling of the size of the BLR as a function of luminosity is significantly different from those previously published, and suggests that the effective ionization parameter in AGN may be a decreasing function of luminosity. We are also able to constrain, subject to our assumption that gravity dominates the motions of the BLR gas, the scaling relationship between the mass of the central black holes and the luminosity in AGN: M \propto L^{0.5+-0.1}. This is inconsistent with all AGN having optical luminosity that is a constant fraction of the Eddington luminosity.
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Using simultaneous modeling of continuum lag-spectrum and broadband SED of Fairall 9 with the H0RIZON-AGN model, the authors obtain H0 = 72.4_{-3.7}^{+3.4} km s^{-1} Mpc^{-1}.
Slim-disk self-shadowing plus accretion-rate-dependent BLR density enhancement explains the observed offsets of high-Eddington AGNs below the canonical R-L relation.
Requiring thermal stability and single-valuedness in the thin-disk Ṁ-Σ plane produces a viscosity law α(X) with X = P_gas/P_rad that eliminates the radiation-pressure dominated instability while preserving the effective-temperature profile.
Presents a public spectroscopic atlas of 887 Southern broad-line AGNs at low redshift, including continuum decompositions and emission-line fits.
Radio precedes X-ray Compton luminosity by ~3 days in the rising hard state but lags by ~8 days in the decaying hard state of GX 339-4, with inner magnetic field strength estimated from accretion rate and truncation radius accounting for both.
Optical spectroscopy is required to unlock the full potential of SKAO extragalactic surveys through precise redshifts, activity diagnostics, HI stacking, and large-scale structure mapping.
Overview chapter summarizing traditional orientation-based and radiation-regulated unification models for AGN, including evolutionary aspects and changing-look AGN.
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Radiation-pressure instability is an artifact of constant-$\alpha$ closure
Requiring thermal stability and single-valuedness in the thin-disk Ṁ-Σ plane produces a viscosity law α(X) with X = P_gas/P_rad that eliminates the radiation-pressure dominated instability while preserving the effective-temperature profile.
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Radio-X-ray Time Lags in GX 339-4: Probing Magnetic Field Transport in Black Hole Accretion
Radio precedes X-ray Compton luminosity by ~3 days in the rising hard state but lags by ~8 days in the decaying hard state of GX 339-4, with inner magnetic field strength estimated from accretion rate and truncation radius accounting for both.