Pat Hall

U. Toronto

The CNOC2 Menagerie

The Canadian Network for Observation Cosmology Field Galaxy Redshift Survey
(CNOC2) has achieved its primary goal of obtaining 6000 faint galaxy redshifts.
I will review some of the main science goals and results of the survey,
and then focus on the serendipitous discovery of a few dozen active galactic
nuclei (AGN) and a handful of gravitational lens candidates.

AGN:  Most AGN and quasars are selected by their unusual optical colors.
The 45 confirmed CNOC2 AGN are the largest sample of AGN selected in the 
optical without regard to color.   They form a valuable check on the 
efficiency of color surveys, and on possible incompleteness in our 
knowledge of the properties of the radio-quiet quasar population.
The results are in general reassuring: color selection does not appear to
introduce extreme biases.  However, this sample does show a higher incidence
of associated MgII absorption than in previous surveys and an incidence of
associated CIV absorption more similar to radio-selected quasar samples than
optically-selected ones.  The sample also includes several unusual AGN, some
of which might be missed by color selection, such as one with a double-peaked
MgII emission line (probably due to a rotating accretion disk), one with an
OIII 3133 broad absorption line, and at least one with absorption instead of
emission lines in the rest UV.

Lenses:  Five objects in the CNOC2 database have a firm redshift from several
spectral features, but also show an additional emission line corresponding to
no known or plausible transition.  It is likely that these emission lines are
Lyman-alpha from faint galaxies gravitationally lensed by the CNOC2 target
galaxy.  High-resolution imaging of these sources can strongly constrain the
mass distribution of the lensing galaxy, and the CNOC2 sample increases the
number of these objects known from two to seven.