The Sloan Digital Sky Survey View of the Palomar-Green Bright Quasar Survey

We investigate the extent to which the Palomar-Green (PG) Bright QuasarSurvey (BQS) is complete and representative of the general quasar population bycomparing with imaging and spectroscopy from the Sloan Digital Sky Survey. Acomparison of SDSS and PG photometry of both stars and quasars reveals the needto apply a color and magnitude recalibration to the PG data. Using the SDSSphotometric catalog, we define the PG's parent sample of objects that are notmain-sequence stars and simulate the selection of objects from this parentsample using the PG photometric criteria and errors. This simulation shows thatthe effective U-B cut in the PG survey is U-B < -0.71 (rather than the intendedU-B < -0.44), implying a color-related incompleteness. As the colordistribution of bright quasars peaks near U-B=-0.7 and the 2-sigma error in U-Bis comparable to the full width of the color distribution of quasars, the colorincompleteness of the BQS is approximately 50% and essentially random withrespect to U-B color for z<0.5. There is, however, a bias against brightquasars at 0.5 < z < 1, which is induced by the color-redshift relation ofquasars (although quasars at z>0.5 are inherently rare in bright surveys in anycase). We find no evidence for any other systematic incompleteness whencomparing the distributions in color, redshift, and FIRST radio properties ofthe BQS and a BQS-like subsample of the SDSS quasar sample. However, theapplication of a bright magnitude limit biases the BQS toward the inclusion ofobjects which are blue in g-i, in particular compared to the full range of g-icolors found among the i-band limited SDSS quasars, and even at i-bandmagnitudes comparable to those of the BQS objects.Comment: 23 pages in emulateapj, accepted for publication in A