High-redshift quasars and star formation in the early universe
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High-redshift quasars and star formation in the early universe. / Dietrich, M.; Appenzeller, I.; Vestergaard, M.; Wagner, S. J.
I: Astrophysical Journal, Bind 564, Nr. 2 I, 10.01.2002, s. 581-591.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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T1 - High-redshift quasars and star formation in the early universe
AU - Dietrich, M.
AU - Appenzeller, I.
AU - Vestergaard, M.
AU - Wagner, S. J.
PY - 2002/1/10
Y1 - 2002/1/10
N2 - In order to derive information on the star formation history in the early universe, we observed six high-redshift (z ≃ 3.4) quasars in the near-infrared to measure the relative iron and Mg II emission strengths. A detailed comparison of the resulting spectra with those of low-redshift quasars show essentially the same Fe II /Mg II emission ratios and very similar continuum and line spectral properties, indicating a lack of evolution of the relative iron to magnesium abundance of the gas since z ≃ 3.4 in bright quasars. On the basis of current chemical evolution scenarios of galaxies, where magnesium is produced in massive stars ending in Type II Supernovae (SNe II), while iron is formed predominantly in SNe la with a delay of ∼1 Gyr and assuming as cosmological parameters H0 = 72 km s-1 Mpc-1, ωM = 0.3, and ωλ = 0.7, we conclude that major star formation activity in the host galaxies of our z ≃ 3.4 quasars must have started already at an epoch corresponding to zf ≃ 10, when the age of the universe was less than 0.5 Gyr.
AB - In order to derive information on the star formation history in the early universe, we observed six high-redshift (z ≃ 3.4) quasars in the near-infrared to measure the relative iron and Mg II emission strengths. A detailed comparison of the resulting spectra with those of low-redshift quasars show essentially the same Fe II /Mg II emission ratios and very similar continuum and line spectral properties, indicating a lack of evolution of the relative iron to magnesium abundance of the gas since z ≃ 3.4 in bright quasars. On the basis of current chemical evolution scenarios of galaxies, where magnesium is produced in massive stars ending in Type II Supernovae (SNe II), while iron is formed predominantly in SNe la with a delay of ∼1 Gyr and assuming as cosmological parameters H0 = 72 km s-1 Mpc-1, ωM = 0.3, and ωλ = 0.7, we conclude that major star formation activity in the host galaxies of our z ≃ 3.4 quasars must have started already at an epoch corresponding to zf ≃ 10, when the age of the universe was less than 0.5 Gyr.
KW - Galaxies: abundances
KW - Galaxies: evolution
KW - Quasars: emission lines
KW - Quasars: general
UR - http://www.scopus.com/inward/record.url?scp=0000475048&partnerID=8YFLogxK
U2 - 10.1086/324337
DO - 10.1086/324337
M3 - Journal article
AN - SCOPUS:0000475048
VL - 564
SP - 581
EP - 591
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2 I
ER -
ID: 229914316