Coronal-line forest active galactic nuclei – I. Physical properties of the emission-line regions. Issue 2 (26th November 2020)

• Record Type: Journal Article
• Authors: Cerqueira-Campos, F C; Rodríguez-Ardila, A; Riffel, R; Marinello, M; Prieto, A; Dahmer-Hahn, L G
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 500:Issue 2(2021)
• Page Start: 2666
• Page End: 2684
• Publication Date: 2020-11-26
• Subjects: galaxies: active -- galaxies: Seyfert -- infrared: galaxies; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa3320
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: Coronal-line forest (CLiF) active galactic nuclei (AGNs) are characterized by strong high-ionization lines, which contrasts with what is found in most AGNs. Here, we carry out a multiwavelength analysis aimed at understanding the physical processes in the narrow-line region (NLR) of these objects, and at discovering whether they are indeed a special class of AGNs. By comparing coronal emission-line ratios we conclude that there are no differences between CLiF and non-CLiF AGNs. We derive physical conditions of the NLR gas and we find electron densities in the range of 3.6 × 10 2 to 1.7 × 10 4 cm −3 and temperatures of 3.7 × 10 3 to 6.3 × 10 4 K, suggesting that the ionization mechanism is associated primarily with photoionization by the AGN. We suggest an NLR dominated by matter-bounded clouds to explain the high-ionization line spectrum observed. The mass of the central black hole, derived from the stellar velocity dispersion, shows that most of the objects have values in the interval 10 7 –10 8 M⊙ . Our results imply that CLiF AGNs are not in a separate category of AGNs. In all optical/near-infrared emission-line properties analysed, they represent an extension to the low/high ends of the distribution within the AGN class.