Coronal-Line Forest AGN: the best view of the inner edge of the AGN torus?

Marvin Rose; Martin Elvis; Clive Tadhunter

doi:10.1093/mnras/stv113

paper

Coronal-Line Forest AGN: the best view of the inner edge of the AGN torus?

arXiv:1501.02705 · doi:10.1093/mnras/stv113

Abstract

We introduce Coronal-Line Forest Active Galactic Nuclei (CLiF AGN), AGN which have a rich spectrum of forbidden high-ionization lines (FHILs, e.g. [FeVII], [FeX] and [NeV]), as well as relatively strong narrow ( $\sim$ 300 km s $^{- 1}$ ) H $α$ emission when compared to the other Balmer transition lines. We find that the kinematics of the CLiF emitting region are similar to those of the forbidden low-ionization emission-line (FLIL) region. We compare emission line strengths of both FHILs and FLILs to CLOUDY photoionization results and find that the CLiF emitting region has higher densities (10 $^{4.5}$ $<$ n $_{H}$ $<$ 10 $^{7.5}$ cm $^{- 3}$ ) when compared to the FLIL emitting region (10 $^{3.0}$ $<$ n $_{H}$ $<$ 10 $^{4.5}$ cm $^{- 3}$ ). We use the photoionization results to calculate the CLiF regions radial distances (0.04 $<$ R $_{C L i F}$ $<$ 32.5 pc) and find that they are comparable to the dust grain sublimation distances (0.10 $<$ R $_{S U B}$ $<$ 4.3 pc). As a result we suggest that the inner torus wall is the most likely location of the CLiF region, and the unusual strength of the FHILs is due to a specific viewing angle giving a maximal view of the far wall of the torus without the continuum being revealed.

arXiv comment22 pages, 14 Figures and 12 Tables. Resubmitted to MNRAS after minor corrections

Coronal-Line Forest AGN: the best view of the inner edge of the AGN torus?

Abstract

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