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Fe II Diagnostic Tools for Quasars

Verner, E.; Bruhweiler, F.; Verner, D.; Johansson, Sveneric LU ; Kallman, T. and Gull, T. (2004) In Astrophysical Journal 611(2). p.780-785
Abstract
The enrichment of Fe relative to α-elements such as O and Mgrepresents a potential means to determine the age of quasars and probethe galaxy formation epoch. To explore how Fe II emission in quasars islinked to physical conditions and abundance, we have constructed an 830level Fe II model atom and investigated through photoionizationcalculations how Fe II emission strengths depend on nonabundancefactors. We have split Fe II emission into three major wavelength bands,Fe II (UV), Fe II (Opt1), and Fe II (Opt2), and explore how the Fe II(UV)/Mg II, Fe II (UV)/Fe II (Opt1), and Fe II (UV)/Fe II (Opt2)emission ratios depend on hydrogen density and ionizing flux in thebroad-line regions (BLRs) of quasars. Our calculations show that (1)similar Fe... (More)
The enrichment of Fe relative to α-elements such as O and Mgrepresents a potential means to determine the age of quasars and probethe galaxy formation epoch. To explore how Fe II emission in quasars islinked to physical conditions and abundance, we have constructed an 830level Fe II model atom and investigated through photoionizationcalculations how Fe II emission strengths depend on nonabundancefactors. We have split Fe II emission into three major wavelength bands,Fe II (UV), Fe II (Opt1), and Fe II (Opt2), and explore how the Fe II(UV)/Mg II, Fe II (UV)/Fe II (Opt1), and Fe II (UV)/Fe II (Opt2)emission ratios depend on hydrogen density and ionizing flux in thebroad-line regions (BLRs) of quasars. Our calculations show that (1)similar Fe II (UV)/Mg II ratios can exist over a wide range of physicalconditions, (2) the Fe II (UV)/Fe II (Opt1) and Fe II (UV)/Fe II (Opt2)ratios serve to constrain ionizing luminosity and hydrogen density, and(3) flux measurements of Fe II bands and knowledge of the ionizing fluxprovide tools to derive distances to BLRs in quasars. To derive all BLRphysical parameters with uncertainties, comparisons of our model withobservations of a large quasar sample at low redshift (z<1) aredesirable. The STIS and NICMOS instruments aboard the Hubble SpaceTelescope offer the best means to provide such observations. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Atomic Processes, Line: Formation, Methods: Numerical, Galaxies: Quasars: Emission Lines
in
Astrophysical Journal
volume
611
issue
2
pages
780 - 785
publisher
University of Chicago Press
external identifiers
  • wos:000223403400013
  • scopus:6044251279
ISSN
0004-637X
DOI
10.1086/422303
language
English
LU publication?
yes
id
6c0c24e3-2937-43a7-85e6-721024ee103e (old id 134101)
date added to LUP
2007-07-20 14:18:23
date last changed
2017-01-01 07:28:49
@article{6c0c24e3-2937-43a7-85e6-721024ee103e,
  abstract     = {The enrichment of Fe relative to α-elements such as O and Mgrepresents a potential means to determine the age of quasars and probethe galaxy formation epoch. To explore how Fe II emission in quasars islinked to physical conditions and abundance, we have constructed an 830level Fe II model atom and investigated through photoionizationcalculations how Fe II emission strengths depend on nonabundancefactors. We have split Fe II emission into three major wavelength bands,Fe II (UV), Fe II (Opt1), and Fe II (Opt2), and explore how the Fe II(UV)/Mg II, Fe II (UV)/Fe II (Opt1), and Fe II (UV)/Fe II (Opt2)emission ratios depend on hydrogen density and ionizing flux in thebroad-line regions (BLRs) of quasars. Our calculations show that (1)similar Fe II (UV)/Mg II ratios can exist over a wide range of physicalconditions, (2) the Fe II (UV)/Fe II (Opt1) and Fe II (UV)/Fe II (Opt2)ratios serve to constrain ionizing luminosity and hydrogen density, and(3) flux measurements of Fe II bands and knowledge of the ionizing fluxprovide tools to derive distances to BLRs in quasars. To derive all BLRphysical parameters with uncertainties, comparisons of our model withobservations of a large quasar sample at low redshift (z&lt;1) aredesirable. The STIS and NICMOS instruments aboard the Hubble SpaceTelescope offer the best means to provide such observations.},
  author       = {Verner, E. and Bruhweiler, F. and Verner, D. and Johansson, Sveneric and Kallman, T. and Gull, T.},
  issn         = {0004-637X},
  keyword      = {Atomic Processes,Line: Formation,Methods: Numerical,Galaxies: Quasars: Emission Lines},
  language     = {eng},
  number       = {2},
  pages        = {780--785},
  publisher    = {University of Chicago Press},
  series       = {Astrophysical Journal},
  title        = {Fe II Diagnostic Tools for Quasars},
  url          = {http://dx.doi.org/10.1086/422303},
  volume       = {611},
  year         = {2004},
}