Elemental Abundances in the Broad Emission Line Region of Quasars at Redshifts larger than 4

M. Dietrich; I. Appenzeller; F. Hamann; J. Heidt; K. Jaeger; Marianne Vestergaard; S. J. Wagner

doi:10.1051/0004-6361:20021697

Elemental Abundances in the Broad Emission Line Region of Quasars at Redshifts larger than 4

M. Dietrich, I. Appenzeller, F. Hamann, J. Heidt, K. Jaeger, Marianne Vestergaard, S. J. Wagner

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Abstract

We present observations of 11 high redshift quasars ($3.9 \la z \la 5.0$) observed with low spectral resolution in the restframe ultraviolet using FORS 1 at the VLT UT 1. The emission-line fluxes of strong permitted and intercombination ultraviolet emission lines are measured to estimate the chemical composition of the line emitting gas. Comparisons to photoionization calculations indicate gas metallicities in the broad emission line region in the range of solar to several times solar. The average of the mean metallicity of each high-z quasar in this sample is $Z/Z_\odot = 4.3 \pm 0.3$. Assuming a chemical evolution time scale of $\tau_{evol} \simeq 0.5 - 0.8$ Gyrs, we derive a redshift of $z_f \simeq 6 {\rm to} 8$ for the onset of the first major star formation episode (H$_o = 65$ km s$^{-1}$ Mpc$^{-1}$, $\Omega_M = 0.3$, $\Omega_\Lambda = 0.7$), corresponding to an age of the universe of several $10^8$ yrs at this epoch. We note that this epoch is also supposed to be the era of re-ionization of the universe.

Originalsprog	Engelsk
Tidsskrift	Astronomy & Astrophysics
Vol/bind	398
Udgave nummer	3
Sider (fra-til)	891-899
ISSN	0004-6361
DOI	https://doi.org/10.1051/0004-6361:20021697
Status	Udgivet - 2 feb. 2003

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10.1051/0004-6361:20021697

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title = "Elemental Abundances in the Broad Emission Line Region of Quasars at Redshifts larger than 4",

abstract = "We present observations of 11 high redshift quasars ($3.9 \la z \la 5.0$) observed with low spectral resolution in the restframe ultraviolet using FORS 1 at the VLT UT 1. The emission-line fluxes of strong permitted and intercombination ultraviolet emission lines are measured to estimate the chemical composition of the line emitting gas. Comparisons to photoionization calculations indicate gas metallicities in the broad emission line region in the range of solar to several times solar. The average of the mean metallicity of each high-z quasar in this sample is $Z/Z_\odot = 4.3 \pm 0.3$. Assuming a chemical evolution time scale of $\tau_{evol} \simeq 0.5 - 0.8$ Gyrs, we derive a redshift of $z_f \simeq 6 {\rm to} 8$ for the onset of the first major star formation episode (H$_o = 65$ km s$^{-1}$ Mpc$^{-1}$, $\Omega_M = 0.3$, $\Omega_\Lambda = 0.7$), corresponding to an age of the universe of several $10^8$ yrs at this epoch. We note that this epoch is also supposed to be the era of re-ionization of the universe.",

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author = "M. Dietrich and I. Appenzeller and F. Hamann and J. Heidt and K. Jaeger and Marianne Vestergaard and Wagner, {S. J.}",

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T1 - Elemental Abundances in the Broad Emission Line Region of Quasars at Redshifts larger than 4

AU - Dietrich, M.

AU - Appenzeller, I.

AU - Hamann, F.

AU - Heidt, J.

AU - Jaeger, K.

AU - Vestergaard, Marianne

AU - Wagner, S. J.

PY - 2003/2/2

Y1 - 2003/2/2

N2 - We present observations of 11 high redshift quasars ($3.9 \la z \la 5.0$) observed with low spectral resolution in the restframe ultraviolet using FORS 1 at the VLT UT 1. The emission-line fluxes of strong permitted and intercombination ultraviolet emission lines are measured to estimate the chemical composition of the line emitting gas. Comparisons to photoionization calculations indicate gas metallicities in the broad emission line region in the range of solar to several times solar. The average of the mean metallicity of each high-z quasar in this sample is $Z/Z_\odot = 4.3 \pm 0.3$. Assuming a chemical evolution time scale of $\tau_{evol} \simeq 0.5 - 0.8$ Gyrs, we derive a redshift of $z_f \simeq 6 {\rm to} 8$ for the onset of the first major star formation episode (H$_o = 65$ km s$^{-1}$ Mpc$^{-1}$, $\Omega_M = 0.3$, $\Omega_\Lambda = 0.7$), corresponding to an age of the universe of several $10^8$ yrs at this epoch. We note that this epoch is also supposed to be the era of re-ionization of the universe.

AB - We present observations of 11 high redshift quasars ($3.9 \la z \la 5.0$) observed with low spectral resolution in the restframe ultraviolet using FORS 1 at the VLT UT 1. The emission-line fluxes of strong permitted and intercombination ultraviolet emission lines are measured to estimate the chemical composition of the line emitting gas. Comparisons to photoionization calculations indicate gas metallicities in the broad emission line region in the range of solar to several times solar. The average of the mean metallicity of each high-z quasar in this sample is $Z/Z_\odot = 4.3 \pm 0.3$. Assuming a chemical evolution time scale of $\tau_{evol} \simeq 0.5 - 0.8$ Gyrs, we derive a redshift of $z_f \simeq 6 {\rm to} 8$ for the onset of the first major star formation episode (H$_o = 65$ km s$^{-1}$ Mpc$^{-1}$, $\Omega_M = 0.3$, $\Omega_\Lambda = 0.7$), corresponding to an age of the universe of several $10^8$ yrs at this epoch. We note that this epoch is also supposed to be the era of re-ionization of the universe.

KW - astro-ph

U2 - 10.1051/0004-6361:20021697

DO - 10.1051/0004-6361:20021697

M3 - Journal article

SN - 0004-6361

VL - 398

SP - 891

EP - 899

JO - Astronomy and Astrophysics Supplement Series

JF - Astronomy and Astrophysics Supplement Series

IS - 3

ER -

Elemental Abundances in the Broad Emission Line Region of Quasars at Redshifts larger than 4

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