RADIO PROPERTIES OF OPTICALLY SELECTED QUASARS

Approximately one-quarter (256 objects) of the Large Bright Quasar Survey (LBQS) has been observed with the VLA at 8.4 GHz, resulting in 44 detections (17%) with a median 3 sigma noise limit of 0.29 mJy. Quasars with radio luminosity detectable at this limit are underrepresented at faint absolute blue magnitudes (M(B) greater than or equal to-24), an effect which cannot be explained by a potential LBQS selection bias against quasars which have large radio luminosities and small optical luminosities. The radio-loud (8 GHz luminosity > 10(25) W Hz(-1)) fraction is observed to change as a function of redshift and M(B), for M(B) < -24, although the causal variable is ambiguous. The description most consistent with the available data is that radio-loud fraction is approximately constant over the range -27.5 less than or similar to M(B) less than or similar to-24 and increases at brighter absolute magnitudes. The radio-loud fraction as a function of red shift reaches a local maximum at z approximate to 1, and, aside from the effects of increased radio-loud fraction at bright M(B), remains roughly constant to redshifts approaching 5. The log R(8.4) distribution (radio-to-optical luminosity ratio) of the current LBQS sample may be bimodal, but the results of statistical tests are ambiguous, requiring a larger sample size to become definite.