TY - JOUR

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 -