Spectral line variability amplitudes in AGNs

Abstract

We present the results of a long-term variability campaign of very broad-line AGNs with line widths broader than FWHM $>$ 5000 kms$^{-1}$. The main goal of our investigation was to study whether the widths of the optical broad emission lines are correlated with the optical intensity variations on timescales of years. Our AGN sample consisted of 10 objects. We detected a significant correlation between optical continuum variability amplitudes and H$β$ emission line widths (FWHM) and, to a lesser degree, between H$β$ line intensity variations and H$β$ equivalent widths. We add the spectroscopic data of variable AGNs from the literature to supplement our sample. The AGNs from other optical variability campaigns with different line-widths helped to improve the statistical significance of our very broad-line AGN sample. After including the data on 35 additional galaxies, the correlation between optical continuum variability amplitudes and H$β$ emission line widths becomes even more significant and the probability that this is a random correlation drops to 0.7 percent.