Probing spectral properties of radio-quiet quasars searched for optical microvariability

We obtained Sloan Digital Sky Survey spectra for a set of 37 radio-quiet quasars [(radio-quiet quasi-stellar objects (RQQSOs)] that had been previously examined for rapid small-scale optical variations, or microvariability. Their H beta and Mg II emission lines were carefully fit to determine linewidths (full width at half-maximum) as well as equivalent widths (EW) due to the broad emission-line components. The linewidths were used to estimate black hole masses and Eddington ratios, l. Both EWand FWHM are anticorrelated with l. The EW distributions provide no evidence for the hypothesis that a weak jet component in the RQQSOs is responsible for their microvariability.