Recent studies of luminous infrared-selected active galactic nuclei (AGN) suggest that the reddest, most obscured objects display a higher angular clustering amplitude, and thus reside in higher-mass dark matter halos. This is a direct contradiction to the prediction of the simplest unification-by-orientation models of AGN and quasars. However, clustering measurements depend strongly on the "mask" that removes low-quality data and describes the sky and selection function. We find that applying a robust, conservative mask to WISE-selected quasars yields a weaker but still significant difference in the bias between obscured and unobscured quasars. These findings are consistent with results from previous Spitzer surveys, and removes any scale dependence of the bias. For obscured quasars with z = 0.99 we measure a bias of b q = 2.67 ± 0.16, corresponding to a halo mass of log(M h /M ⊙ h −1 ) = 13.3 ± 0.1, while for unobscured sources with z = 1.04 we find b q = 2.04 ± 0.17 with a halo mass log(M h /M ⊙ h −1 ) = 12.8 ± 0.1. This improved measurement indicates that WISE-selected obscured quasars reside in halos only a few times more massive than the halos of their unobscured counterparts, a reduction in the factor of ∼10 larger halo mass as has been previously reported using WISE-selected samples. Additionally, an abundance matching analysis yields lifetimes for both obscured and unobscured quasar phases on the order of a few 100 Myr (∼ 1% of the Hubble time) -however, the obscured phase lasts roughly twice as long, in tension with many model predictions.

Currently, the ability to produce black hole mass estimates using the C iv λ1549 line that are consistent with H β mass estimates is uncertain, due in large part to disagreement between velocity line width measurements for the two lines. This discrepancy between H β and C iv arises from the fact that both line profiles are treated the same way in single-epoch scaling relationships based on the assumption that the broad-line region is virialized, even though a non-virialized emission component is often significant in the C iv line and absent or weak in the H β line. Using quasi-simultaneous optical and ultra-violet spectra for a sample of 85 optically bright quasars with redshifts in the range z = 0.03 − 1.4, we present a significant step along the path to rehabilitating the C iv line for black hole mass estimates. We show that the residuals of velocity line width between C iv and H β are significantly correlated with the peak flux ratio of Si iv+O iv] λ1400 to C iv. Using this relationship, we develop a prescription for estimating black hole masses from the ultra-violet spectrum that agree better with H β-based masses than the traditional C iv masses. The scatter between H β and C iv masses is initially 0.43 dex in our sample and is reduced to 0.33 dex when using our prescription. The peak flux ratio of Si iv+O iv] λ1400 to C iv is an ultraviolet indicator of the suite of spectral properties commonly known as "Eigenvector 1", thus the reduction in scatter between C iv and H β black hole masses is essentially due to removing an Eigenvector 1 bias in C iv-based masses.

We present observed mid-infrared and optical colors and composite spectral energy distributions (SEDs) of type 1 (broad-line) and 2 (narrow-line) quasars selected from Sloan Digital Sky Survey (SDSS) spectroscopy. A significant fraction of powerful quasars are obscured by dust and are difficult to detect in optical photometric or spectroscopic surveys. However, these may be more easily identified on the basis of mid-infrared (MIR) colors and SEDs. Using samples of SDSS type 1 and 2 matched in redshift and [O III] luminosity, we produce composite restframe 0.2-15 μm SEDs based on SDSS, UKIDSS, and Wide-field Infrared Survey Explorer photometry and perform model fits using simple galaxy and quasar SED templates. The SEDs of type 1 and 2 quasars are remarkably similar, with the differences explained primarily by the extinction of the quasar component in the type 2 systems. For both types of quasar, the flux of the active galactic nucleus (AGN) relative to the host galaxy increases with AGN luminosity (L O III [ ] ) and redder observed MIR color, but we find only weak dependencies of the composite SEDs on mechanical jet power as determined through radio luminosity. We conclude that luminous quasars can be effectively selected using simple MIR color criteria similar to those identified previously (W1 W2 0.7; > -Vega), although these criteria miss many heavily obscured objects. Obscured quasars can be further identified based on optical-IR colors (for example, u W3 AB). These results illustrate the power of large statistical studies of obscured quasars selected on the basis of MIR and optical photometry.

We have built a sample of 74 radio-selected broad absorption line quasars from the Sloan Digital Sky Survey Data Release 5 (SDSS DR5) and Faint Images of the Radio Sky at Twenty Centimeters (FIRST), along with a well matched sample of 74 unabsorbed "normal" quasars. The sources have been observed with the NRAO Very Large Array/Expanded Very Large Array at 8.4 GHz (3.5 cm) and 4.9 GHz (6 cm). All sources have additional archival 1.4 GHz (21 cm) data. Here we present the measured radio fluxes, spectral indices, and our initial findings. The percentage of BAL quasars with extended structure (on the order of 10%) in our sample is similar to previous studies at similar resolutions, suggesting that BAL quasars are indeed generally compact, at least at arsecond resolutions. The majority of sources do not appear to be significantly variable at 1.4 GHz, but we find two previously unidentified BAL quasars that may fit into the "polar" BAL category. We also identify a significant favoring of steeper radio spectral index for BAL compared to non-BAL quasars. This difference is apparent for several different measures of the spectral index, and persists even when restricting the samples to only include compact objects. Because radio spectral index is a statistical indicator of viewing angle for large samples, these results suggest that BAL quasars do have a range of orientations but are more often observed farther from the jet axis compared to normal quasars.

Recent work has found evidence for a difference in the bias and dark matter halo masses of WISE-selected obscured and unobscured quasars, implying a distinction between these populations beyond random line-of-sight effects. However, the significance of this difference in the most up-to-date measurements is relatively weak, at ∼2σ for individual measurements but bolstered by agreement from different techniques, including angular clustering and cross-correlations with cosmic microwave background (CMB) lensing maps. Here, we expand the footprint of previous work, aiming to improve the precision of both methods. In this larger area we correct for position dependent selection effects, in particular fluctuations of the WISE-selected quasar density as a function of Galactic latitude. We also measure the crosscorrelation of the obscured and unobscured samples and confirm that they are well-matched in redshift, both centred at z = 1. Combined with very similar detection fractions and magnitude distributions in the long-wavelength WISE bands, this redshift match strongly supports the fact that IR selection identifies obscured and unobscured quasars of similar bolometric luminosity. Finally, we perform cross-correlations with confirmed spectroscopic quasars, again confirming the results from other methods -obscured quasars reside in haloes a factor of 3 times more massive than unobscured quasars. This difference is significant at the ∼5σ level when the measurements are combined, strong support for the idea that obscuration in at least some quasars is tied to the larger environment, and may have an evolutionary component.