A Model for Type 2 Coronal Line Forest (CLiF) AGN

TL;DR

This paper introduces a model for CLiF AGN that links viewing angle and emission line strength, providing insights into AGN structure and the ratio of torus height to radius, with results matching observations.

Contribution

The paper presents a novel model connecting viewing angles to emission line strengths in CLiF AGN, aiding understanding of AGN-torus geometry and emission mechanisms.

Findings

Model accurately predicts [FeVII] emission at various angles.

Good agreement between model predictions and observed emission lines.

Relationship established between AGN type ratio and torus h/r ratio.

Abstract

We present a model for the classification of Coronal-Line Forest Active Galactic Nuclei (CLiF AGN). CLiF AGN are of special interest due to their remarkably large number of emission lines, especially forbidden high ionization lines (FHILs). Rose et al. (2015a) suggest that their emission is dominated by reflection from the inner wall of the obscuring region rather than direct emission from the accretion disk. This makes CLiF AGN laboratories to test AGN-torus models. Modeling AGN as an accreting supermassive black hole, surrounded by a cylinder of dust and gas, we show a relationship between viewing angle and the revealed area of the inner wall. From the revealed area, we can determine the amount of FHIL emission at various angles. We calculate the strength of [FeVII]{\lambda}6087 emission for a number of intermediate angles (30$^{\circ}$, 40$^{\circ}$, and 50$^{\circ}$) and compare the results with the luminosity of the observed emission line from six known CLiF AGN. We find that there is good agreement between our model and the observational results. The model also enables us to determine the relationship between the type 2 : type 1 AGN fraction vs the ratio of torus height to radius, h/r.