Long term variability of the Broad Emission Line profiles in AGN

TL;DR

This study presents a decade-long analysis of broad emission line variability in three AGNs, revealing different BLR geometries and structural complexities through spectral profile changes and flux correlations.

Contribution

It provides the first long-term spectral monitoring of these AGNs, identifying distinct BLR structures and their evolution over time.

Findings

3C 390.3 and NGC 5548 exhibit disk-like BLR geometry.

NGC 4151's BLR appears to have multiple kinematic components.

BLR sizes are estimated from continuum-line lag measurements.

Abstract

Results of a long-term monitoring ($\gtrsim 10$ years) of the broad line and continuum fluxes of three Active Galactic Nuclei (AGN), 3C 390.3, NGC 4151, and NGC 5548, are presented. We analyze the H$\alpha$ and H$\beta$ profile variations during the monitoring period and study different details (as bumps, absorption bands) which can indicate structural changes in the Broad Line Region (BLR). The BLR dimensions are estimated using the time lags between the continuum and the broad lines flux variations. We find that in the case of 3C 390.3 and NGC 5548 a disk geometry can explain both the broad line profiles and their flux variations, while the BLR of NGC 4151 seems more complex and is probably composed of two or three kinematically different regions.