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

TL;DR

This study investigates the spectral properties of radio-quiet quasars and Seyfert 1 galaxies to understand the mechanisms behind their optical microvariability, finding no evidence linking weak jets to this variability.

Contribution

It expands previous research by including new spectra of 46 objects and analyzing their emission lines to explore correlations with microvariability.

Findings

No correlation between emission line properties and microvariability.

Spectral properties do not support weak jet components as the cause of microvariability.

Most trends consistent with previous work, except lower luminosity association.

Abstract

In the context of AGN unification scheme rapid variability properties play an important role in understanding any intrinsic differences between sources in different classes. In this respect any clue based on spectral properties will be very useful toward understanding the mechanisms responsible for the origin of rapid small scale optical variations, or microvariability. Here we have added spectra of 46 radio-quiet quasars (RQQSOs) and Seyfert 1 galaxies to those of our previous sample of 37 such objects, all of which had been previously searched for microvariability. We took new optical spectra of 33 objects and obtained 13 others from the literature. Their \hbeta and \mgii emission lines were carefully fit to determine line widths (FWHM) as well as equivalent widths (EW) due to the broad emission line components. The line widths were used to estimate black hole masses and Eddington ratios, $\ell$. Both EW and FWHM are anticorrelated with $\ell$. Nearly all trends were in agreement with our previous work, although the tendency for sources exhibiting microvariability to be of lower luminosity was not confirmed. Most importantly, this whole sample of EW distributions provides no evidence for the hypothesis that a weak jet component in the radio quiet AGNs is responsible for their microvariability.