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 greater than or similar to 6.5 quasars discovered using the Pan-STARRS1 survey. We use a sample of 15 z greater than or similar to 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 greater than or similar to 6.5 quasars show large blueshifts of the broad C IV lambda 1549 emission line compared to the systemic redshift of the quasars, with a median value similar to 3x higher than a quasar sample at z similar to 1; (2) we estimate the quasars' black hole masses (M-BH similar to (0.3-5) x. 10(9) M circle dot) via modeling of the Mg II lambda 2798 emission line and rest-frame UV continuum and find that quasars at high redshift accrete their material (with <(Lbol L-Edd)> = 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 similar to 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 mu m 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.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/626178 |
| Date | 06 November 2017 |
| Creators | Mazzucchelli, C., Bañados, 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., Rosa, G. De, Hennawi, J., Chambers, K. C., Greiner, J., Burgett, W., Draper, P. W., Kaiser, N., Kudritzki, R.-P., Magnier, E., Metcalfe, N., Waters, C., Wainscoat, R. J. |
| Contributors | Univ Arizona, Steward Observ |
| Publisher | IOP PUBLISHING LTD |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | Article |
| Rights | © 2017. The American Astronomical Society. All rights reserved. |
| Relation | http://stacks.iop.org/0004-637X/849/i=2/a=91?key=crossref.cd1437f87b0e6d3188785fd91f4999d3 |
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