Eight new luminous z ≥ 6 quasars discovered via SED model fitting of VISTA, WISE and Dark Energy Survey Year 1 observations
We present the discovery and spectroscopic confirmation with the ESO NTT and Gemini South telescopes of eight new 6.0 < z < 6.5 quasars with z$$_{AB}$$ < 21.0. These quasars were photometrically selected without any star-galaxy morphological criteria from 1533 deg$$^{2}$$ using SED model fitting to photometric data from the Dark Energy Survey (g, r, i, z, Y), the VISTA Hemisphere Survey (J, H, K) and the Wide-Field Infrared Survey Explorer (W1, W2). The photometric data was fitted with a grid of quasar model SEDs with redshift dependent Lyman-{\alpha} forest absorption and a range of intrinsic reddening as well as a series of low mass cool star models. Candidates were ranked using on a SED-model based $$\chi^{2}$$-statistic, which is extendable to other future imaging surveys (e.g. LSST, Euclid). Our spectral confirmation success rate is 100% without the need for follow-up photometric observations as used in other studies of this type. Combined with automatic removal of the main types of non-astrophysical contaminants the method allows large data sets to be processed without human intervention and without being over run by spurious false candidates. We also present a robust parametric redshift estimating technique that gives comparable accuracy to MgII and CO based redshift estimators. We find two z $$\sim$$ 6.2 quasars with HII near zone sizes < 3 proper Mpc which could indicate that these quasars may be young with ages < 10$^6$ - 10$^7$ years or lie in over dense regions of the IGM. The z = 6.5 quasar VDESJ0224-4711 has J$$_{AB}$$ = 19.75 is the second most luminous quasar known with z > 6.5.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP)
- Contributing Organization:
- DES; WISE; VISTA
- Grant/Contract Number:
- AC05-00OR22725; AC02-07CH11359
- OSTI ID:
- 1361377
- Alternate ID(s):
- OSTI ID: 1343963
- Report Number(s):
- FERMILAB-PUB-16-570-AE-PPD; arXiv:1701.04852; KJ0402000; KJ0503000; ERKJ311; ERKJEPM; TRN: US1702458
- Journal Information:
- Monthly Notices of the Royal Astronomical Society, Vol. 468, Issue 4; ISSN 0035-8711
- Publisher:
- Royal Astronomical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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