An Optical/Near-Infrared Study of Radio-Loud Quasar Environments I. Methods and z=1-2 Observations

Abstract

We have conducted an optical/near-infrared study of the environments of radio-loud quasars (RLQs) at redshifts z=0.6-2. In this paper we discuss the sample selection and observations for the z=1-2 subsample and the reduction and cataloguing techniques used. We discuss technical issues at some length, since few detailed descriptions of near-IR data reduction and multicolor object cataloguing are currently available in single literature references. Our sample of 33 RLQs contains comparable numbers of flat- and steep- radio spectrum sources and sources of various radio morphologies, and spans a similar range of absolute magnitude and radio power, allowing us to disentangle dependence of environment on such properties from redshift evolution. We use the standard ``shift-and-stare'' method of creating deep mosaiced images where the exposure time (and thus the RMS noise) at each pixel is not constant across the mosaic. An unusual feature of our reduction procedure is the creation of images with constant RMS noise from such mosaics. We adopted this procedure to enable use of the FOCAS detection package over almost the entire mosaic instead of only in the area of deepest observation where the RMS noise is constant, thereby roughly doubling our areal coverage. We correct the object counts in our fields for stellar contamination using the SKY model of Cohen (1995) and compare the galaxy counts to those in random fields. Even after accounting for possible systematic magnitude offsets we find a significant excess of K>=19 galaxies. Analysis and discussion of this excess population is presented by Hall & Green (1998).

Accepted to ApJS; 49 pages including 12 figures and 8 tables. Also available from http://www.astro.utoronto.ca/~hall/thesis.html

References in corpus (5)

• Near-Infrared Galaxy Counts to J and K ~ 24 as a Function of Image Size
• An Optical/Near-Infrared Study of Radio-Loud Quasar Environments II. Imaging Results
• K-Band Galaxy Counts in the South Galactic Pole Region
• The ESO K'-band Galaxy Survey - Galaxy Counts
• The Interpretation of Near-Infrared Star Counts at the South Galactic Pole

Cited by in corpus (26)

• Spectral Energy Distributions and Multiwavelength Selection of Type 1 Quasars
• Distant Radio Galaxies and their Environments
• Binary Quasars in the Sloan Digital Sky Survey: Evidence for Excess Clustering on Small Scales
• The First Appearance of the Red Sequence of Galaxies in Proto-Clusters at 2<~z<~3
• The K20 survey. III. Photometric and spectroscopic properties of the sample
• The Luminosity Dependence of Quasar Clustering
• A Review of Exoplanetary Biosignatures
• The CORALS Survey II: Clues to Galaxy Clustering Around QSOs from z_abs ~ z_em Damped Lyman Alpha Systems
• Proto-Clusters with Evolved Populations around Radio Galaxies at z~2.5
• Cluster Selection and the Evolution of Brightest Cluster Galaxies
• Near-Infrared Properties of Moderate-Redshift Galaxy Clusters: Luminosity Functions and Density Profiles
• A Deep Multicolor Survey. VI. Near-Infrared Observations, Selection Effects, and Number Counts
• Extremely Red Objects in the Field of QSO 1213-0017: A Galaxy Concentration at z=1.31
• Overdensities of Extremely Red Objects in the Fields of High-Redshift Radio-Loud Quasars
• Very Red and Extremely Red Galaxies in the Fields of z ~ 1.5 Radio-Loud Quasars
• The Near-Infrared properties of the host galaxies of radio quasars
• An excess of damped Lyman alpha galaxies near QSOs
• Cluster of galaxies around seven radio-loud QSOs at 1<z<1.6: K-band images
• Near-Infrared Observations of the Environments of Radio Quiet QSOs at z >~ 1
• The density of extremely red objects around high-z radio-loud AGN
• The cluster environments of radio-loud quasars at 0.6 < z < 1.1
• Infrared observations of gravitational lensing in Abell 2219 with CIRSI
• CFHT AO Imaging of the CLASS Gravitational Lens System B1359+154
• Tunable-filter imaging of quasar fields at z~1. I. A cluster around MRC B0450-221
• A multi-wavelength survey of AGN in the XMM-LSS field: I. Quasar selection via the KX technique
• Wide Field Multiband Imaging of Low Redshift Quasar Environments