Revisited Abundance Diagnostics in Quasars: Fe II/Mg II Ratios
(2003) In Astrophysical Journal 592(2). p.59-62- Abstract
- Both the Fe II UV emission in the 2000-3000 Å region [Fe II(UV)]and resonance emission line complex of Mg II at 2800 Å areprominent features in quasar spectra. The observed Fe II(UV)/Mg IIemission ratios have been proposed as means to measure the buildup ofthe Fe abundance relative to that of the alpha-elements C, N, O, Ne,and Mg as a function of redshift. The current observed ratios show largescatter and no obvious dependence on redshift. Thus, it remainsunresolved whether a dependence on redshift exists and whether theobserved Fe II(UV)/Mg II ratios represent a real nucleosynthesisdiagnostic. We have used our new 830 level model atom for Fe<SUP>+</SUP>in photoionization calculations, reproducing the physical conditions inthe... (More)
- Both the Fe II UV emission in the 2000-3000 Å region [Fe II(UV)]and resonance emission line complex of Mg II at 2800 Å areprominent features in quasar spectra. The observed Fe II(UV)/Mg IIemission ratios have been proposed as means to measure the buildup ofthe Fe abundance relative to that of the alpha-elements C, N, O, Ne,and Mg as a function of redshift. The current observed ratios show largescatter and no obvious dependence on redshift. Thus, it remainsunresolved whether a dependence on redshift exists and whether theobserved Fe II(UV)/Mg II ratios represent a real nucleosynthesisdiagnostic. We have used our new 830 level model atom for Fe<SUP>+</SUP>in photoionization calculations, reproducing the physical conditions inthe broad-line regions of quasars. This modeling reveals thatinterpretations of high values of Fe II(UV)/Mg II are sensitive not onlyto Fe and Mg abundance, but also to other factors such asmicroturbulence, density, and properties of the radiation field. We findthat the Fe II(UV)/Mg II ratio combined with Fe II(UV)/Fe II(optical)emission ratio, where Fe II(optical) denotes Fe II emission in 4000-6000Å band, can be used as a reliable nucleosynthesis diagnostic forthe Fe/Mg abundance ratios for the physical conditions relevant to thebroad-line regions of quasars. This has extreme importance for quasarobservations with the Hubble Space Telescope and also with the futureJames Webb Space Telescope. (Less)
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https://lup.lub.lu.se/record/130515
- author
- Verner, E. ; Bruhweiler, F. ; Verner, D. ; Johansson, Sveneric LU and Gull, T.
- organization
- publishing date
- 2003
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Atomic Processes, Line: Formation, Methods: Numerical, Galaxies: Quasars: Emission Lines
- in
- Astrophysical Journal
- volume
- 592
- issue
- 2
- pages
- 59 - 62
- publisher
- American Astronomical Society
- external identifiers
-
- wos:000184408300002
- scopus:0042918051
- ISSN
- 0004-637X
- DOI
- 10.1086/377571
- language
- English
- LU publication?
- yes
- id
- fa18155e-ef3b-4234-9c00-2cbf349f4f68 (old id 130515)
- date added to LUP
- 2016-04-01 15:51:34
- date last changed
- 2022-12-12 06:46:45
@article{fa18155e-ef3b-4234-9c00-2cbf349f4f68,
abstract = {{Both the Fe II UV emission in the 2000-3000 Å region [Fe II(UV)]and resonance emission line complex of Mg II at 2800 Å areprominent features in quasar spectra. The observed Fe II(UV)/Mg IIemission ratios have been proposed as means to measure the buildup ofthe Fe abundance relative to that of the alpha-elements C, N, O, Ne,and Mg as a function of redshift. The current observed ratios show largescatter and no obvious dependence on redshift. Thus, it remainsunresolved whether a dependence on redshift exists and whether theobserved Fe II(UV)/Mg II ratios represent a real nucleosynthesisdiagnostic. We have used our new 830 level model atom for Fe<SUP>+</SUP>in photoionization calculations, reproducing the physical conditions inthe broad-line regions of quasars. This modeling reveals thatinterpretations of high values of Fe II(UV)/Mg II are sensitive not onlyto Fe and Mg abundance, but also to other factors such asmicroturbulence, density, and properties of the radiation field. We findthat the Fe II(UV)/Mg II ratio combined with Fe II(UV)/Fe II(optical)emission ratio, where Fe II(optical) denotes Fe II emission in 4000-6000Å band, can be used as a reliable nucleosynthesis diagnostic forthe Fe/Mg abundance ratios for the physical conditions relevant to thebroad-line regions of quasars. This has extreme importance for quasarobservations with the Hubble Space Telescope and also with the futureJames Webb Space Telescope.}},
author = {{Verner, E. and Bruhweiler, F. and Verner, D. and Johansson, Sveneric and Gull, T.}},
issn = {{0004-637X}},
keywords = {{Atomic Processes; Line: Formation; Methods: Numerical; Galaxies: Quasars: Emission Lines}},
language = {{eng}},
number = {{2}},
pages = {{59--62}},
publisher = {{American Astronomical Society}},
series = {{Astrophysical Journal}},
title = {{Revisited Abundance Diagnostics in Quasars: Fe II/Mg II Ratios}},
url = {{https://lup.lub.lu.se/search/files/4494473/624153.pdf}},
doi = {{10.1086/377571}},
volume = {{592}},
year = {{2003}},
}