TY - JOUR
T1 - Probing Early Supermassive Black Hole Growth and Quasar Evolution with Near-infrared Spectroscopy of 37 Reionization-era Quasars at 6.3 <
AU - Yang, Jinyi
AU - Wang, Feige
AU - Fan, Xiaohui
AU - Barth, Aaron J.
AU - Hennawi, Joseph F.
AU - Nanni, Riccardo
AU - Bian, Fuyan
AU - Davies, Frederick B.
AU - Farina, Emanuele P.
AU - Schindler, Jan Torge
AU - Bañados, Eduardo
AU - Decarli, Roberto
AU - Eilers, Anna Christina
AU - Green, Richard
AU - Guo, Hengxiao
AU - Jiang, Linhua
AU - Li, Jiang Tao
AU - Venemans, Bram
AU - Walter, Fabian
AU - Wu, Xue Bing
AU - Yue, Minghao
N1 - Publisher Copyright:
© 2021. The American Astronomical Society. All rights reserved.
PY - 2021/12/20
Y1 - 2021/12/20
N2 - We report the results of near-infrared spectroscopic observations of 37 quasars in the redshift range 6.3 < z ≤ 7.64, including 32 quasars at z > 6.5, forming the largest quasar near-infrared spectral sample at this redshift. The spectra, taken with Keck, Gemini, VLT, and Magellan, allow investigations of central black hole mass and quasar rest-frame ultraviolet spectral properties. The black hole masses derived from the Mg ii emission lines are in the range (0.3–3.6) × 109 M ⊙, which requires massive seed black holes with masses ≳103–104 M ⊙, assuming Eddington accretion since z = 30. The Eddington ratio distribution peaks at λ Edd ∼ 0.8 and has a mean of 1.08, suggesting high accretion rates for these quasars. The C iv–Mg ii emission-line velocity differences in our sample show an increase of C iv blueshift toward higher redshift, but the evolutionary trend observed from this sample is weaker than the previous results from smaller samples at similar redshift. The Fe ii/Mg ii flux ratios derived for these quasars up to z = 7.6, compared with previous measurements at different redshifts, do not show any evidence of strong redshift evolution, suggesting metal-enriched environments in these quasars. Using this quasar sample, we create a quasar composite spectrum for z > 6.5 quasars and find no significant redshift evolution of quasar broad emission lines and continuum slope, except for a blueshift of the C iv line. Our sample yields a strong broad absorption line quasar fraction of ∼24%, higher than the fractions in lower-redshift quasar samples, although this could be affected by small sample statistics and selection effects.
AB - We report the results of near-infrared spectroscopic observations of 37 quasars in the redshift range 6.3 < z ≤ 7.64, including 32 quasars at z > 6.5, forming the largest quasar near-infrared spectral sample at this redshift. The spectra, taken with Keck, Gemini, VLT, and Magellan, allow investigations of central black hole mass and quasar rest-frame ultraviolet spectral properties. The black hole masses derived from the Mg ii emission lines are in the range (0.3–3.6) × 109 M ⊙, which requires massive seed black holes with masses ≳103–104 M ⊙, assuming Eddington accretion since z = 30. The Eddington ratio distribution peaks at λ Edd ∼ 0.8 and has a mean of 1.08, suggesting high accretion rates for these quasars. The C iv–Mg ii emission-line velocity differences in our sample show an increase of C iv blueshift toward higher redshift, but the evolutionary trend observed from this sample is weaker than the previous results from smaller samples at similar redshift. The Fe ii/Mg ii flux ratios derived for these quasars up to z = 7.6, compared with previous measurements at different redshifts, do not show any evidence of strong redshift evolution, suggesting metal-enriched environments in these quasars. Using this quasar sample, we create a quasar composite spectrum for z > 6.5 quasars and find no significant redshift evolution of quasar broad emission lines and continuum slope, except for a blueshift of the C iv line. Our sample yields a strong broad absorption line quasar fraction of ∼24%, higher than the fractions in lower-redshift quasar samples, although this could be affected by small sample statistics and selection effects.
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U2 - 10.3847/1538-4357/ac2b32
DO - 10.3847/1538-4357/ac2b32
M3 - Article
AN - SCOPUS:85123247588
VL - 923
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2
M1 - 262
ER -