A COMPARATIVE-STUDY OF THE MICROVARIABILITY PROPERTIES IN RADIO-LOUD AND RADIO-QUIET QUASARS

We have performed photometric optical observations of a sample of 17 c ore-dominated radio-loud quasars (CRLQs) and 17 radio-quiet quasars (R QQs). The aims were to confirm the existence of microvariations in str ictly radio-quiet objects and to compare the properties of the variati ons in both types of quasars. Great care was taken to avoid selection effects and spurious biases in the samples. We present a new observati onal and statistical procedure for searching for microvariability, bas ed on the analysis of variance. The results show that microvariations in RQQs may be as frequent as in CRLQs. The implications for the physi cal models for microvariations are briefly discussed.