We present spectra of six luminous quasars at z ~ 2, covering rest wavelengths 1600-3200 A. The fluxes of the UV Fe II emission lines and Mg II 2798 doublet, the line widths of Mg II, and the 3000 A luminosity were obtained from the spectra. These quantities were compared with those of low-redshift quasars at z = 0.06 - 0.55 studied by Tsuzuki et al. In a plot of the Fe II(UV)/Mg II flux ratio as a function of the cental black hole mass, Fe II(UV)/Mg II in our z ~ 2 quasars is systematically greater than in the low-redshift quasars. We confermed that luminosity is not responsible for this excess. It is unclear whether this excess is caused by rich Fe abundance at z ~ 2 over low-redshift or by non-abundance effects such as high gas density, strong radiation field, and high microturbulent velocity.
@article{arxiv.0902.2057,
title = {Ultraviolet Fe II emission in z ~ 2 quasars},
author = {Hiroaki Sameshima and Jose Maza and Yoshiki Matsuoka and Shinki Oyabu and Kimiaki Kawara and Yuzuru Yoshii and Naoko Asami and Nobuyuki Ienaka and Yumihiko Tsuzuki},
journal= {arXiv preprint arXiv:0902.2057},
year = {2009}
}
Comments
5pages, 5figures, 2tables, accepted for publication in MNRAS