We present a simple model of how quasars occupy dark matter halos from z = 0 to z = 5 using the observed mBH −σ relation and quasar luminosity functions. This provides a way for observers to statistically infer host halo masses for quasar observations using luminosity and redshift alone. Our model is deliberately simple and sidesteps any need to explicitly describe the physics. In spite of its ...

We have examined the occurrence of extremely red objects (EROs) in the fields of 13 luminous quasars (11 radio-loud and two radio-quiet) at 1.8 < z < 3.0. The average surface density of Ks 19 mag EROs is 2–3 times higher than in large, random-field surveys, and the excess is significant at the 3 level even after taking into account that the ERO distribution is highly inhomogeneous. This is the ...

Over the last few years, the Sloan Digital Sky Survey (SDSS) has discovered several hundred quasars with redshift between 4.0 and 6.4. Including the effects of magnification bias, one expects a priori that an appreciable fraction of these objects are gravitationally lensed. We have used the Advanced Camera for Surveys on the Hubble Space Telescope to carry out a snapshot imaging survey of high-...

The integrated line width derived from CO spectroscopy provides a powerful tool to study the internal kinematics of extragalactic objects, including quasars at high redshift, provided that the observed line width can be properly translated to more conventionally used kinematical parameters of galaxies. We show, through construction of a Ks-band CO Tully-Fisher relation for nearby galaxies spann...

We present Spitzer IRS observations of a complete sample of 57 SDSS type-1 quasars at z ∼ 1. Aromatic features at 6.2 and/or 7.7 μm are detected in about half of the sample and show profiles similar to those seen in normal galaxies at both lowand high-redshift, indicating a star-formation origin for the features. Based on the ratio of aromatic to star-formation IR (SFIR) luminosities for normal...

The recently discovered tight correlation between supermassive black hole mass and central velocity dispersion for both inactive and active galaxies suggests a possibility to estimate the black hole mass from the measured central velocity dispersion. However, for most AGNs it is difficult to measure the central velocity dispersions of their host galaxies directly with the spectroscopic studies....

A new sample of 341 possible local QSOs are presented, which are in the vicinity of low redshift galaxies. Physical characteristics of the sample quasars are determined and previously reported relations are confirmed: density redshift, absolute mag – radius, absolute mag – mass, mass – radius, mass – luminosity, and mass – density. These relations seem to support the basic assumptions that quas...

Aims. We study the uniformity of the distribution of compact flat-spectrum AGN on the sky and the evolution of their relativistic jets with cosmic epoch. Methods. A complete sample of compact extragalactic radio sources at 15 GHz was recently compiled to conduct the MOJAVE program. The MOJAVE sample comprises 133 radio-loud flat-spectrum AGN with compact relativistic outflows detected at parsec...

With close pairs of quasars at different redshifts, a background quasar sightline can be used to study a foreground quasar’s environment in absorption. We used a sample of 17 Lyman limit systems with column density NHI > 10 19 cm selected from 149 projected quasar pair sightlines, to investigate the clustering pattern of optically thick absorbers around luminous quasars at z ∼ 2.5. Specifically...

We report new continuum observations of fourteen z∼6 quasars at 250 GHz and fourteen quasars at 1.4 GHz. We summarize all recent millimeter and radio observations of the sample of the thirty-three quasars known with 5.71 ≤ z ≤ 6.43, and present a study of the rest frame far-infrared (FIR) properties of this sample. These quasars were observed with the Max Plank Millimeter Bolometer Array (MAMBO...