relation $R_{BLR}\propto L^{\sim0.5}$. In other words, the mean size of BLR of 3C390.3 can be estimated by the continuum luminosity (line luminosity), while, the continuum emission strengthening leads to the size of BLR decreasing (not increasing) in different moments for 3C390.3. Then, we compared our results of 3C390.3 with the previous results reported in the literature for the other double-peaked emitters, and found that before to clearly correct effects from disk physical parameters varying (such as effects of disk precession) for long-term observed line spectra, it is not so meaningful to discuss the correlation of line parameters of double-peaked broad lines. Furthermore, due to the probable ’external’ ionizing source with so far unclear structures, it is hard to give one conclusion that the positive correlation between the line width and the line flux can be found for all double-peaked emitters, even after the considerations of disk physical parameters varying. However, once one positive correlation of broad line parameters was found, the accretion disk origination of the broad line should be firstly considered.'
title: 'Correlation between Line Width and Line Flux of Double-Peaked Broad H$\alpha$ of 3C390.3'
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Galaxies:Active – Galaxies:nuclei – Galaxies:Seyfert – quasars:Emission lines – Galaxies:individual: 3C390.3

Introduction
