This study examines the large-scale environments of radio-loud and radio-quiet quasars. The large-scale environments of quasars are interesting because quasars are thought to be triggered by interactions with neighboring galaxies and/or intercluster gas. Studies show that quasars reside in overdense regions, and radio-quiet quasars, while more likely to have close companions than field galaxies, tend to reside in poorer clusters than radio-loud quasars. To improve our understanding of the correlation between radio properties and environment, we imaged a carefully selected sample from the Large Bright Quasar Survey (LBQS). The sample consists of sixteen quasars in the redshift range 0.4 < z < 0.5 with absolute blue magnitudes between -23.0 and -26.5. Six of the quasars are radio-loud, and the ten remaining quasars have 8.4 GHz luminosities <= 10(23.5) W * Hz(-1) . R-band images of the quasars and control fields were taken at the Steward 90 inch. The same fields were then imaged in the H-band using a new wide-field infrared camera, PISCES. PISCES is an ideal instrument for this study because its 8.5' field corresponds to a projected distance of 2.4 Mpc at z ~ 0.4. This allows simultaneous sampling of the quasar environment and a control field. The H and R-band photometry allows identification of companion galaxies, and the color information helps to discriminate between foreground and cluster galaxies. Preliminary results are presented comparing galaxy counts within 1 Mpc of the quasars to field galaxy counts.
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1998