Strong FeII emission in NLS1s: An unsolved mystery

In Panda et al. 2018a, we constructed a refined sample from the original Shen et al.(2011) QSO catalog. Based on our hypothesis — the main driver of the Quasar Main Sequence is the maximum of the accretion disk temperature (T^BBB) defined by the Big Blue Bump on the Spectral Energy Distribution (Panda et al. 2017; Panda et al. 2018b). We select the four extreme sources that have R^FeII ⩾ 4.0 and use {CIGALE (Boquien et al. 2018) to fit their multi—band photometric data. We also perform detailed spectral fitting including the Fe II pseudo—continuum (based on Śniegowska et al. 2018) to estimate and compare the value of R^FEII. We show the dependence of FeII strength on changing metallicity.