Complex Broad Emission Line Profiles of AGN - Geometry of the Broad Line Region

TL;DR

This paper investigates the complex shapes of broad emission lines in AGN spectra, proposing a two-component model combining accretion disk emission and surrounding region contributions to explain observed line profiles.

Contribution

It introduces a two-component model for broad emission lines in AGN, effectively describing both single-peaked and double-peaked profiles, advancing understanding of BLR geometry.

Findings

Model successfully reproduces observed line profiles

Supports the presence of accretion disks in AGN

Explains diversity in BEL shapes

Abstract

The Broad Emission Lines (BELs) in spectra of type 1 Active Galactic Nuclei (AGN) can be very complex, indicating a complex Broad Line Region (BLR) geometry. According to the standard unification model one can expect an accretion disk around a supermassive black hole in all AGN. Therefore, a disk geometry is expected in the BLR. However, a small fraction of BELs show double-peaked profiles which indicate the disk geometry. Here, we discuss a two-component model, assuming an emission from the accretion disk and one additional emission from surrounding region. We compared the modeled BELs with observed ones (mostly broad H$\alpha$ and H$\beta$ profiles) finding that the model can well describe single-peaked and double-peaked observed broad line profiles.