3C390.3: More Stable Evidence for Origination of Double-Peaked Broad Balmer Lines from Accretion Disk Near Central Black Hole

TL;DR

This study confirms that the double-peaked broad Balmer lines in 3C390.3 originate from an accretion disk near its central black hole, using spectral analysis, reverberation mapping, and disk modeling.

Contribution

It provides new evidence supporting the accretion disk origin of double-peaked emission lines in 3C390.3 through detailed spectral and light-curve analysis.

Findings

Accretion disk model fits observed line profiles well.

Reverberation mapping supports disk-origin of broad lines.

Disk parameters influence BLR size measurements.

Abstract

In this manuscript, the structure of broad emission line regions (BLRs) of well-mapping double-peaked emitter (AGN with broad double-peaked low-ionization emission lines) 3C390.3 is studied. Besides the best fitted results for double-peaked broad optical balmer lines of 3C390.3 by theoretical disk model, we try to find another way to further confirm the origination of double-peaked line from accretion disk. Based on the long-period observed spectra in optical band around 1995 collected from AGN WATCH project, the theoretical disk parameters of disk-like BLRs supposed by elliptical accretion disk model (Eracleous et al. 1995) have been well determined. Through the theoretical disk-like BLRs, characters of observed light-curves of broad double-peaked H$\alpha$ of 3C390.3 can be well reproduced based on the reverberation mapping technique. Thus the accretion disk model is preferred as one better model for BLRs of 3C390.3. Furthermore, we can find that different disk parameters should lead to some different results about size of BLRs of 3C390.3 from the one measured through observational data, which indicates the measured disk parameters are significantly valid for 3C390.3. After that, the precession of theoretical elliptical disk-like BLRs being considered, we can find that the expected line profile in 2000 by theoretical model is consistent with the observed line profile by HST around 2000. Based on the results, we can further believe that the origination of broad double-peaked balmer emission lines of 3C390.3 are from accretion disk around central black hole.