We present an updated and revised analysis of the relationship between the Hβ broad-line region (BLR) radius and the luminosity of the active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness decompositions of the host galaxies of 9 new AGNs imaged with the Hubble Space Telescope Wide Field Camera 3. The surface brightness decompositions allow us to create "AGN-free" images of the galaxies, from which we measure the starlight contribution to the optical luminosity measured through the ground-based spectroscopic aperture. We also incorporate 20 new reverberation-mapping measurements of the Hβ time lag, which is assumed to yield the average Hβ BLR radius. The final sample includes 41 AGNs covering four orders of magnitude in luminosity. The additions and updates incorporated here primarily affect the low-luminosity end of the R BLR -L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of α = 0.533 +0.035 −0.033 , consistent with previous work and with simple photoionization arguments. Only two AGNs appear to be outliers from the relationship, but both of them have monitoring light curves that raise doubt regarding the accuracy of their reported time lags. The scatter around the relationship is found to be 0.19 ± 0.02 dex, but would be decreased to 0.13 dex by the removal of these two suspect measurements. A large fraction of the remaining scatter in the relationship is likely due to the inaccurate distances to the AGN host galaxies. Our results help support the possibility that the R BLR -L relationship could potentially be used to turn the BLRs of AGNs into standardizable candles. This would allow the cosmological expansion of the Universe to be probed by a separate population of objects, and over a larger range of redshifts.

After the All-Sky Automated Survey for SuperNovae (ASAS-SN) discovered a significant brightening of the inner region of NGC 2617, we began a ∼ 70 day photometric and spectroscopic monitoring campaign from the X-ray through near-infrared (NIR) wavelengths. We report that NGC 2617 went through a dramatic outburst, during which its X-ray flux increased by over an order of magnitude followed by an increase of its optical/ultraviolet (UV) continuum flux by almost an order of magnitude. NGC 2617, classified as a Seyfert 1.8 galaxy in 2003, is now a Seyfert 1 due to the appearance of broad optical emission lines and a continuum blue bump. Such "changing look Active Galactic Nuclei (AGN)" are rare and provide us with important insights about AGN physics. Based on the Hβ line width and the radius-luminosity relation, we estimate the mass of central black hole to be (4 ± 1) × 10 7 M ⊙ . When we crosscorrelate the light curves, we find that the disk emission lags the X-rays, with the lag becoming longer as we move from the UV (2 − 3 days) to the NIR (6 − 9 days). Also, the NIR is more heavily temporally smoothed than the UV. This can largely be explained by a simple model of a thermally emitting thin disk around a black hole of the estimated mass that is illuminated by the observed, variable X-ray fluxes.

Quasars are galaxies hosting accreting supermassive black holes; due to their brightness, they are unique probes of the early universe. To date, only a few quasars have been reported at (<800 Myr after the big bang). In this work, we present six additional quasars discovered using the Pan-STARRS1 survey. We use a sample of 15 quasars to perform a homogeneous and comprehensive analysis of this highest-redshift quasar population. We report four main results: (1) the majority of quasars show large blueshifts of the broad C iv λ1549 emission line compared to the systemic redshift of the quasars, with a median value ∼3× higher than a quasar sample at ; (2) we estimate the quasars’ black hole masses ( (0.3–5) × 109 M ⊙) via modeling of the Mg ii λ2798 emission line and rest-frame UV continuum and find that quasars at high redshift accrete their material (with ) at a rate comparable to a luminosity-matched sample at lower redshift, albeit with significant scatter (0.4 dex); (3) we recover no evolution of the Fe ii/Mg ii abundance ratio with cosmic time; and (4) we derive near-zone sizes and, together with measurements for quasars from recent work, confirm a shallow evolution of the decreasing quasar near-zone sizes with redshift. Finally, we present new millimeter observations of the [C ii] 158 μm emission line and underlying dust continuum from NOEMA for four quasars and provide new accurate redshifts and [C ii]/infrared luminosity estimates. The analysis presented here shows the large range of properties of the most distant quasars.

We present ALMA detections of the [C II] 158 μm emission line and the underlying far-infrared (FIR) continuum of three quasars at 6.6<z<6.9 selected from the VIKING survey. The [C II] line fluxes range between 1.6 and 3.4 Jy km s −1 ([C II] luminosities ∼(1.9-3.9)×10 9 L e ). We measure continuum flux densities of 0.56-3.29 mJy around 158 μm (rest frame), with implied FIR luminosities of (0.6-7.5)×1012 L e and dust masses8 M e . In one quasar we derive a dust temperature of 30 9 12 -+ K from the continuum slope, below the canonical value of 47 K. Assuming that the [C II] and continuum emission are powered by star formation, we find star formation rates from 100 to 1600 M e yr −1 based on local scaling relations. The L [C II] /L FIR ratios in the quasar hosts span a wide range from (0.3-4.6)×10 −3 , including one quasar with a ratio that is consistent with local star-forming galaxies. We find that the strength of the L [C II] and 158 μm continuum emission in z6 quasar hosts correlates with the quasar's bolometric luminosity. In one quasar, the [C II] line is significantly redshifted by ∼1700 km s −1 with respect to the Mg II broad emission line. Comparing to values in the literature, we find that, on average, the Mg II is blueshifted by 480 km s −1 (with a standard deviation of 630 km s −1 ) with respect to the host galaxy redshift, i.e., one of our quasars is an extreme outlier. Through modeling we can rule out a flat rotation curve for our brightest [C II] emitter. Finally, we find that the ratio of black hole mass to host galaxy (dynamical) mass is higher by a factor of 3-4 (with significant scatter) than local relations.