Astrophys. J., 849, 91-91 (2017/November-2)
Physical properties of 15 quasars at z >= 6.5.
MAZZUCCHELLI C., BANADOS E., VENEMANS B.P., DECARLI R., FARINA E.P., WALTER F., EILERS A.-C., RIX H.-W., SIMCOE R., STERN D., FAN X., SCHLAFLY E., DE ROSA G., HENNAWI J., CHAMBERS K.C., GREINER J., BURGETT W., DRAPER P.W., KAISER N., KUDRITZKI R.-P., MAGNIER E., METCALFE N., WATERS C. and WAINSCOAT R.J.
Abstract (from CDS):
Quasars are galaxies hosting accreting supermassive black holes; due to their brightness, they are unique probes of the early universe. To date, only a few quasars have been reported at z 6.5 (<800 Myr after the big bang). In this work, we present six additional z 6.5 quasars discovered using the Pan-STARRS1 survey. We use a sample of 15 z 6.5 quasars to perform a homogeneous and comprehensive analysis of this highest-redshift quasar population. We report four main results: (1) the majority of z 6.5 quasars show large blueshifts of the broad C IV λ1549 emission line compared to the systemic redshift of the quasars, with a median value ∼3x higher than a quasar sample at z∼1; (2) we estimate the quasars' black hole masses (MBH ∼(0.3-5) x 109 M☉) via modeling of the Mg II λ2798 emission line and rest-frame UV continuum and find that quasars at high redshift accrete their material (with <(Lbol/LEdd)>=0.39) at a rate comparable to a luminosity-matched sample at lower redshift, albeit with significant scatter (0.4 dex); (3) we recover no evolution of the Fe II/Mg II abundance ratio with cosmic time; and (4) we derive near-zone sizes and, together with measurements for z∼6 quasars from recent work, confirm a shallow evolution of the decreasing quasar near-zone sizes with redshift. Finally, we present new millimeter observations of the [C II] 158 µm emission line and underlying dust continuum from NOEMA for four quasars and provide new accurate redshifts and [C II]/infrared luminosity estimates. The analysis presented here shows the large range of properties of the most distant quasars.
© 2017. The American Astronomical Society. All rights reserved.
galaxies: high-redshift - quasars: general - quasars: general
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