Gemini Near-infrared Spectroscopy of Luminous z~6 Quasars
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Gemini Near-infrared Spectroscopy of Luminous z~6 Quasars. / Jiang, Linhua; Fan, Xiaohui; Vestergaard, Marianne; Kurk, Jaron D.; Walter, Fabian; Kelly, Brandon C.; Strauss, Michael A.
I: Astronomical Journal, Bind 134, Nr. 3, 1150, 11.07.2007.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Gemini Near-infrared Spectroscopy of Luminous z~6 Quasars
AU - Jiang, Linhua
AU - Fan, Xiaohui
AU - Vestergaard, Marianne
AU - Kurk, Jaron D.
AU - Walter, Fabian
AU - Kelly, Brandon C.
AU - Strauss, Michael A.
PY - 2007/7/11
Y1 - 2007/7/11
N2 - We present Gemini near-infrared spectroscopic observations of six luminous quasars at z=5.8$\sim$6.3. Five of them were observed using Gemini-South/GNIRS, which provides a simultaneous wavelength coverage of 0.9--2.5 $\mu$m in cross dispersion mode. The other source was observed in K band with Gemini-North/NIRI. We calculate line strengths for all detected emission lines and use their ratios to estimate gas metallicity in the broad-line regions of the quasars. The metallicity is found to be supersolar with a typical value of $\sim$4 Z_{\sun}, and a comparison with low-redshift observations shows no strong evolution in metallicity up to z$\sim$6. The FeII/MgII ratio of the quasars is 4.9+/-1.4, consistent with low-redshift measurements. We estimate central BH masses of 10^9 to 10^{10} M_{\sun} and Eddington luminosity ratios of order unity. We identify two MgII $\lambda\lambda$2796,2803 absorbers with rest equivalent width W_0^{\lambda2796}>1 \AA at 2.2z 1.5 \AA at z>3 in the spectra, with the two most distant absorbers at z=4.8668 and 4.8823, respectively. The redshift number densities (dN/dz) of MgII absorbers with W_0^{\lambda2796}>1.5 \AA are consistent with no cosmic evolution up to z>4.
AB - We present Gemini near-infrared spectroscopic observations of six luminous quasars at z=5.8$\sim$6.3. Five of them were observed using Gemini-South/GNIRS, which provides a simultaneous wavelength coverage of 0.9--2.5 $\mu$m in cross dispersion mode. The other source was observed in K band with Gemini-North/NIRI. We calculate line strengths for all detected emission lines and use their ratios to estimate gas metallicity in the broad-line regions of the quasars. The metallicity is found to be supersolar with a typical value of $\sim$4 Z_{\sun}, and a comparison with low-redshift observations shows no strong evolution in metallicity up to z$\sim$6. The FeII/MgII ratio of the quasars is 4.9+/-1.4, consistent with low-redshift measurements. We estimate central BH masses of 10^9 to 10^{10} M_{\sun} and Eddington luminosity ratios of order unity. We identify two MgII $\lambda\lambda$2796,2803 absorbers with rest equivalent width W_0^{\lambda2796}>1 \AA at 2.2z 1.5 \AA at z>3 in the spectra, with the two most distant absorbers at z=4.8668 and 4.8823, respectively. The redshift number densities (dN/dz) of MgII absorbers with W_0^{\lambda2796}>1.5 \AA are consistent with no cosmic evolution up to z>4.
KW - astro-ph
U2 - 10.1086/520811
DO - 10.1086/520811
M3 - Journal article
VL - 134
JO - The Astronomical Journal
JF - The Astronomical Journal
SN - 0004-6256
IS - 3
M1 - 1150
ER -
ID: 123371493