Far-UV Fe Emission as Proxy of Eddington Ratios. (arXiv:2106.09010v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Zheng_W/0/1/0/all/0/1">Wei Zheng</a>
The Eddington ratio is a key parameter that governs the diversity of quasar
properties. It can be scaled with a strong anti-correlation between optical Fe
II and [O III] emission. In search of such indicators in the far-UV band, the
HST far-UV spectra of 150 low-redshift quasars are analyzed in combination with
their optical SDSS counterparts. The strength of Fe II+Fe III 1123 emission is
significantly correlated with that of optical Fe II. A moderate correlation may
also exist between Fe II 1071 and optical Fe II. The finding opens the
possibility that far-UV Fe II emission may serve as a new gauge of the
Eddington ratios. The high- and low-ionization lines in the far-UV band display
different patterns: for the quasars with higher Eddington ratios, the
low-ionization UV lines are stronger, and the high-ionization lines are broader
and weaker.
The Eddington ratio is a key parameter that governs the diversity of quasar
properties. It can be scaled with a strong anti-correlation between optical Fe
II and [O III] emission. In search of such indicators in the far-UV band, the
HST far-UV spectra of 150 low-redshift quasars are analyzed in combination with
their optical SDSS counterparts. The strength of Fe II+Fe III 1123 emission is
significantly correlated with that of optical Fe II. A moderate correlation may
also exist between Fe II 1071 and optical Fe II. The finding opens the
possibility that far-UV Fe II emission may serve as a new gauge of the
Eddington ratios. The high- and low-ionization lines in the far-UV band display
different patterns: for the quasars with higher Eddington ratios, the
low-ionization UV lines are stronger, and the high-ionization lines are broader
and weaker.
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