Quasar Elemental Abundances at High Redshifts
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Quasar Elemental Abundances at High Redshifts. / Dietrich, M.; Hamann, F.; Shields, J. C.; Constantin, A.; Heidt, J.; Jaeger, K.; Vestergaard, Marianne; Wagner, S. J.
I: Astrophysical Journal, Bind 589, Nr. 2, 722, 24.02.2003.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Quasar Elemental Abundances at High Redshifts
AU - Dietrich, M.
AU - Hamann, F.
AU - Shields, J. C.
AU - Constantin, A.
AU - Heidt, J.
AU - Jaeger, K.
AU - Vestergaard, Marianne
AU - Wagner, S. J.
PY - 2003/2/24
Y1 - 2003/2/24
N2 - We examine rest-frame ultraviolet spectra of 70 high redshift quasars (z>3.5) to study the chemical enrichment history of the gas closely related to the quasars, and thereby estimate the epoch of first star formation. The fluxes of several ultraviolet emission lines were investigated within the framework of the most recent photoionization models to estimate the metallicity of the gas associated with the high-z quasars. Standard photoionization parameters and the assumption of secondary nitrogen enrichment indicate an average abundance of Z/Z_sol = 4 to 5 in the line emitting gas. Assuming a time scale of t_evol = 0.5 - 0.8 Gyrs for the chemical enrichment of the gas, the first major star formation for quasars with z>=4 should have started at a redshift of z_f = 6 - 8, corresponding to an age of the universe of several 10^8 yrs (H_o = 65 km/s/Mpc, Omega_M = 0.3, Omega_Lambda = 0.7). We note that this also appears to be the era of re-ionization of the universe. Finally, there is some evidence for a positive luminosity - metallicity relation in this high redshift quasar sample.
AB - We examine rest-frame ultraviolet spectra of 70 high redshift quasars (z>3.5) to study the chemical enrichment history of the gas closely related to the quasars, and thereby estimate the epoch of first star formation. The fluxes of several ultraviolet emission lines were investigated within the framework of the most recent photoionization models to estimate the metallicity of the gas associated with the high-z quasars. Standard photoionization parameters and the assumption of secondary nitrogen enrichment indicate an average abundance of Z/Z_sol = 4 to 5 in the line emitting gas. Assuming a time scale of t_evol = 0.5 - 0.8 Gyrs for the chemical enrichment of the gas, the first major star formation for quasars with z>=4 should have started at a redshift of z_f = 6 - 8, corresponding to an age of the universe of several 10^8 yrs (H_o = 65 km/s/Mpc, Omega_M = 0.3, Omega_Lambda = 0.7). We note that this also appears to be the era of re-ionization of the universe. Finally, there is some evidence for a positive luminosity - metallicity relation in this high redshift quasar sample.
KW - astro-ph
U2 - 10.1086/374662
DO - 10.1086/374662
M3 - Journal article
VL - 589
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2
M1 - 722
ER -
ID: 123370915