Testing narrow‐line Seyfert 1 scenarios with photoionization models
/ Authors
/ Abstract
Narrow Line Seyfert 1 (NLSy1) galaxies have recently received a lot of attention due to their unusual optical--X-ray properties which are not yet well understood. Photoionization models of the circum-nuclear emission/absorption regions allow to investigate scenarios to explain the main characteristics of NLSy1s, i.e., (i) extremely steep X-ray spectra within the ROSAT energy range, (ii) narrow Balmer lines and (iii) weak forbidden lines except for some relatively strong high-ionization iron lines. Here, we focus on (iii). In particular, we study the influence of different EUV - soft-X-ray spectral shapes (a giant soft excess, a steep X-ray powerlaw, presence of a warm absorber) and NLR cloud properties on the predicted optical emission-line ratios. The calculations were carried out with Ferland's code Cloudy.
Journal: Astronomische Nachrichten
DOI: 10.1002/1521-3994(199908)320:4/5<310::AID-ASNA310>3.0.CO;2-N