2009/02/12 by H. Sameshima, Hiroaki Sameshima, Jose Maza +15
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Galaxies: Formation, Evolution, Phenomena #astro-ph.CO #astro-ph.GA
paper · pdf · doi:10.1111/j.1365-2966.2009.14605.x
5pages, 5figures, 2tables, accepted for publication in MNRAS
arxiv created 2009/02/12 · openalex publication_date 2009/04/01 · arxiv updated 2009/12/01 · openalex created_date 2019/06/27 · openalex updated_date 2026/07/28
We present spectra of six luminous quasars at z∼ 2, covering rest wavelengths 1600−3200 Å. The fluxes of the UV Fe ii emission lines and Mg iiλ2798 doublet, the line widths of Mg ii and the 3000 Å 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 central black hole mass, Fe ii(UV)/Mg ii in our z∼ 2 quasars is systematically greater than in the low-redshift quasars. We confirmed 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.