Optical Variability of Radio-Luminous PG Quasars

We observed the 10 quasars with the highest core radio luminosity in the Palomar-Green Bright Quasar Survey to look for both short- (i.e., intra- and interday) and long- (i.e., months to years) term optical variability. In most models, the central quasi-stellar object (QSO) radio source is thought to have high apparent radio luminosity because a jet of relativistic material is beamed close to our line of sight. We expect more variability in the radio luminous sample than in a sample of radio-quiet QSOs if a shock in a beamed jet is the cause of variability; seven of 10 quasars showed short-term variability, and all 10 quasars have long-term variability. Comparison with other samples indicates our radio-loud QSOs are more likely to have short-term variations than radio-quiet QSOs. This result supports the model of QSO variability being dominated by shock waves in the relativistic plasma jet.