The CaFe Project: Optical Fe ii and Near-infrared Ca ii Triplet Emission in Active Galaxies. I. Photoionization Modeling
Swayamtrupta Panda, Mary Loli Martínez-Aldama, Murilo Marinello, Bożena Czerny, Paola Marziani, Deborah Dultzin
Abstract
Abstract Optical Fe ii emission is a strong feature in quasar spectra originating in the broad-line region (BLR). The difficulty in understanding the complex Fe ii pseudo-continuum has led us to search for other reliable, simpler ionic species such as Ca ii . In this first part of the series, we confirm the strong correlation between the strengths of two emission features, the optical Fe ii and the NIR Ca ii , both from observations and photoionization modeling. With the inclusion of an up-to-date compilation of observations with both optical Fe ii and NIR Ca ii measurements, we span a wider and more extended parameter space and confirm the common origin of these two spectral features with our photoionization models using CLOUDY . Taking into account the effect of dust into our modeling, we constrain the BLR parameter space (primarily in terms of the ionization parameter and local cloud density) as a function of the strengths of Fe ii and Ca ii emission.