Gemini Near-Infrared Spectroscopy of Luminous z ∼ 6 Quasars: Chemical Abundances, Black Hole Masses, and Mg II Absorption

By Linhua Jiang, Xiaohui Fan, M. Vestergaard, J. Kurk, F. Walter, B. Kelly, M. Strauss. 2007

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We present Gemini near-infrared spectroscopic observations of six luminous quasars at z = 5.8 to ∼6.3. Five of them were observed using Gemini South GNIRS, which provides a simultaneous wavelength coverage of 0.9-2.5 μm in cross-dispersion mode. The other source was observed in the 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 ∼4 Z⊙, and a comparison with low-redshift observations shows no strong evolution in metallicity up to z ∼ 6. The Fe II/Mg II ratio of the quasars is 4.9 ± 1.4, consistent with low-redshift measurements. We estimate central black hole masses of 109-1010 M⊙ and Eddington luminosity ratios of order unity. We identify two Mg II λλ2796, 2803 absorbers with rest equivalent width W > 1 Å at 2.2 < z < 3 and three Mg II absorbers with W > 1.5 Å 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 Mg II absorbers with W > 1.5 Å are consistent with no cosmic evolution up to z > 4.

Subfields: Astronomy and Astrophysics

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Citations in the corpus

Biases in Virial Black Hole Masses: An SDSS Perspective (2007, background): “For example, Kurk et al. (2007) and Jiang et al. (2007a) have obtained observations of both MgII and CIV in four z∼ 6 quasars.”
THE FINAL SDSS HIGH-REDSHIFT QUASAR SAMPLE OF 52 QUASARS AT z > 5.7 (2016, methodology): “…shows that these luminous quasars harbor billion-solar-mass black holes and emit near the Eddington limit, suggesting the rapid growth of central black holes at this early epoch (e.g., Jiang et al. 2007; Kurk et al. 2007; Willott et al. 2010a; De Rosa et al. 2014; Jun et al. 2015; Wu et al. 2015).”
EDDINGTON-LIMITED ACCRETION AND THE BLACK HOLE MASS FUNCTION AT REDSHIFT 6 (2010, methodology): “Using this method it has been possible to measure black hole masses for SDSS quasars at z = 6 (Willott et al. 2003; Jiang et al. 2007; Kurk et al. 2007; Kurk et al. 2009).”
An ALMA [C ii] Survey of 27 Quasars at z > 5.94 (2018, background): “The typical black hole mass is~ M109 , implying that these quasars radiate close to their Eddington limit (Jiang et al. 2007; De Rosa et al. 2011, 2014; Mazzucchelli et al. 2017).”
DISCOVERY OF THREE z > 6.5 QUASARS IN THE VISTA KILO-DEGREE INFRARED GALAXY (VIKING) SURVEY (2013, background): “These black hole masses are very similar to those powering quasars at z ∼ 6 that were discovered in the SDSS main survey (e.g., Jiang et al. 2007; Kurk et al. 2007; De Rosa et al. 2011), but generally more massive than those of the z ∼ 6 quasars discovered in the CFHQS (Willott et al. 2010a).”
A SURVEY OF z ∼ 6 QUASARS IN THE SLOAN DIGITAL SKY SURVEY DEEP STRIPE. I. A FLUX-LIMITED SAMPLE AT zAB < 21 (2007, background): “Their emission lines show solar or supersolar metallicity in the broad line regions, indicating that there was vigorous star formation and element enrichment in the first gigayear of cosmic time (e.g. Barth et al. 2003; Maiolino et al. 2003; Jiang et al. 2007; Kurk et al. 2007).”
Observations of feedback from radio-quiet quasars - I. Extents and morphologies of ionized gas nebulae (2013, background): “Our adopted definition produces similar fractions of radio-loud sources among type 1 and type 2 quasars (Reyes et al. 2008), but yields a lower radio-loud fraction than the traditional definitions based on a constant optical continuum to radio continuum ratio (e.g., Jiang et al. 2007).”
STAR FORMATION AND GAS KINEMATICS OF QUASAR HOST GALAXIES AT z ∼ 6: NEW INSIGHTS FROM ALMA (2013, background): “…et al. 2009, 2011; and the Panoramic Survey Telescope and Rapid Response System [Pan-STARRS], Morganson et al. 2012) with optical z-band magnitudes from 18.8 to 24.4 and inferred SMBH masses from 108 to a few 109 M (Kurk et al. 2007; Jiang et al. 2007; Willott et al. 2010; De Rosa et al. 2011).”
The Effect of Radiation Pressure on Virial Black Hole Mass Estimates and the Case of Narrow-Line Seyfert 1 Galaxies (2008, background): “…to estimate BH masses in large sample of galaxies from zero to high redshifts (e.g. Willott et al. 2003; McLure & Dunlop 2004; Vestergaard 2004; Jiang et al. 2007) and are deemed accurate only from a statistical point of view on large samples of objects since a single measurement can be wrong…”
The Sloan Digital Sky Survey Reverberation Mapping Project: Sample Characterization (2018, methodology): “For the FIRST radio matches, we follow the procedures in Jiang et al. (2007) and Shen et al. (2011): we match the SDSS-RM quasars with the FIRST source catalog (14 Dec, 2017 version) with a matching radius of 30′′ and estimate the radio loudness R = f6cm/ f2500, where f6cm and f2500 are the flux…”
A SURVEY OF z ∼ 6 QUASARS IN THE SLOAN DIGITAL SKY SURVEY DEEP STRIPE. II. DISCOVERY OF SIX QUASARS AT zAB>21 (2009, background): “In luminous z ∼ 6 quasars black hole masses measured in this way are usually several billion solar masses (e.g. Jiang et al. 2007; Kurk et al. 2007).”
EVIDENCE FOR NON-EVOLVING Fe ii/Mg ii RATIOS IN RAPIDLY ACCRETING z ∼ 6 QSOs (2011, methodology): “The average difference is equal to ∆z=0.02 with a maximum of ∆z=0.08 for J1411+1217 (Jiang et al. 2007, online Appendix Fig.”
CONSTRAINTS ON BLACK HOLE GROWTH, QUASAR LIFETIMES, AND EDDINGTON RATIO DISTRIBUTIONS FROM THE SDSS BROAD-LINE QUASAR BLACK HOLE MASS FUNCTION (2010, background): “At high-redshift SMBHs with masses MBH ∼ 109 are already in place by z ∼ 6 (e.g., Fan et al. 2001b; Jiang et al. 2007), and therefore the high-z BLQSO BHMF places important constraints on the formation and growth of seed SMBHs (e.g., Volonteri et al. 2003, 2008; Lodato & Natarajan 2007).”
BLACK HOLE MASS ESTIMATES AND EMISSION-LINE PROPERTIES OF A SAMPLE OF REDSHIFT z > 6.5 QUASARS (2013, methodology): “Therefore we did not attempt to isolate their individual components (see also Jiang et al. 2007); 2. we ignored Al iii λ1857 and Si iii] λ1892 emission lines that are blended with the strong C iii] emission since the latter is typically significantly brighter (e.g., Vanden Berk et al. 2001); and 3.…”
MOLECULAR GAS IN z ∼ 6 QUASAR HOST GALAXIES (2010, unknown): “In particular, the CO redshifts of J1044−0125 and J1148+5251 are in good agreement with the values derived from the CIII] λ1909Å and SiIV λ1400Å broad emission lines with high-quality near-infrared spectroscopy (Jiang et al. 2007; Ryan-Weber et al. 2009).”
SUBARU HIGH-z EXPLORATION OF LOW-LUMINOSITY QUASARS (SHELLQs). I. DISCOVERY OF 15 QUASARS AND BRIGHT GALAXIES AT 5.7 < z < 6.9 (2016, unknown): “The chemical enrichment, and thus the preceding star formation history, can be measured with strong metal emission lines arising from ionized gas around the quasar nuclei (e.g., Jiang et al. 2007; De Rosa et al. 2011, 2014).”