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)
Please use this url to cite or link to this publication:
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
- 2024-01-25 18:23:03
@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}}, }