We present sub-mm photometry for 11 Hyperluminous Infrared Galaxies (HLIRGs, LIR > 10 h 65 L⊙) and use radiative transfer models for starbursts and AGN to examine the nature of the IR emission. In all the sources both a starburst and AGN are required to explain the total IR emission. The mean starburst fraction is 35%, with a range spanning 80% starburst dominated to 80% AGN dominated. In all c...

We compute two-point correlation functions and measure the shear signal due to galaxy-galaxy lensing for 80 000 optically identified and 5 700 radio-loud AGN from Data Release 4 (DR4) of the Sloan Digital Sky Survey. Halo occupation models are used to estimate halo masses and satellite fractions for these two types of AGN. The large sample size allows us to separate AGN according to the stellar...

The connection between normal and active galaxies is reviewed, by summarizing our progress on answering nine key questions. (1) Do all galaxies contain massive dark objects (MDOs)? (2) Are these MDOs actually supermassive black holes? (3) Why are the dark objects so dark? (4) Do all galaxies contain an Active Galactic Nucleus (AGN)? (5) Are the " dwarf AGN " really AGN? (6) Does AGN activity co...

AGN are elusive objects across that are visible across the electromagnetic spectrum. Currently, there is no complete picture of AGN formation and evolution in galaxy clusters. A general understanding of the AGN population has been impeded by cluster and selection biases and recent studies have shown that there is a large population of obscured or optically unremarkable AGN in galaxy clusters. T...

Using the known numbers and evolution of unobscured AGN, and assuming that there is a large number of corresponding obscured AGN — as expected if AGN unification is correct — we predict the infrared number counts of AGN. These agree well with the observed GOODS Spitzer data at 3.6, 8 and 24 μm, provided that the dust content of the obscuring torus is ∼ 2x less than assumed. This strongly suppor...

We review critically the evidence concerning the fraction of Active Galactic Nuclei (AGN) which appear as Type 2 AGN, carefully distinguishing strict Type 2 AGN from both more lightly reddened Type 1 AGN, and from low excitation narrow line AGN, which may represent a different mode of activity. Low excitation AGN occur predominantly at low luminosities; after removing these, true Type 2 AGN rep...

In this study, we investigate the relationship between the star formation rate (SFR) and AGN luminosity (LAGN) for ∼2000 X-ray detected AGN. The AGN span over three orders of magnitude in X-ray luminosity (1042 <L2−8 keV < 1045.5 erg s−1) and are in the redshift range z = 0.2–2.5. Using infrared (IR) photometry (8–500 μm), including deblended Spitzer and Herschel images and taking into account ...

We present the two–point correlation function (2PCF) of narrow-line active galactic nuclei (AGN) selected within the First Data Release of the Sloan Digital Sky Survey. Using a sample of 13605 AGN in the redshift range 0.055 < z < 0.2, we find that the AGN auto–correlation function is consistent with the observed galaxy auto–correlation function on scales 0.2hMpc to > 100hMpc. The AGN hosts tra...

The connection between normal and active galaxies is reviewed, by summarizing our progress on answering nine key questions. (1) Do all galaxies contain massive dark objects (MDOs)? (2) Are these MDOs actually supermassive black holes? (3) Why are the dark objects so dark? (4) Do all galaxies contain an Active Galactic Nucleus (AGN)? (5) Are the “dwarf AGN ” really AGN? (6) Does AGN activity cor...

Using Spitzer-IRS spectroscopy, we investigate the ubiquity of Active Galactic Nuclei (AGN) in a complete (≈ 94 percent), volume-limited sample of the most bolometrically-luminous galaxies (LIR, 8−1000 μm & (0.3–20) ×10 10 L⊙) to D < 15 Mpc. Our analyses are based on the detection of the high-excitation emission line [NeV]λ14.32 μm (97.1 eV) to unambiguously identify AGN activity. We find that ...