التفاصيل البيبلوغرافية
| العنوان: |
Eight new luminous z ≥ 6 quasars discovered via SED model fitting of VISTA, WISE and Dark Energy Survey Year 1 observations. |
| المؤلفون: |
Reed, S. L., McMahon, R. G., Martini, P., Banerji, M., Auger, M., Hewett, P. C., Koposov, S. E., Gibbons, S. L. J., Gonzalez-Solares, E., Ostrovski, F., Tie, S. S., Abdalla, F. B., Allam, S., Benoit-Lévy, A., Bertin, E., Brooks, D., Buckley-Geer, E., Burke, D. L., Carnero Rosell, A., Carrasco Kind, M. |
| المصدر: |
Monthly Notices of the Royal Astronomical Society; Jul2017, Vol. 468 Issue 4, p4702-4718, 17p |
| مصطلحات موضوعية: |
QUASARS, ACTIVE galaxies, GALAXY formation, SPECTRAL energy distribution |
| الشركة/الكيان: |
EUROPEAN Southern Observatory |
| مستخلص: |
We present the discovery and spectroscopic confirmation with the European Southern Observatory New Technology Telescope (NTT) and Gemini South telescopes of eight new, and the rediscovery of two previously known, 6.0 < z < 6.5 quasars with zAB < 21.0. These quasars were photometrically selected without any morphological criteria from 1533 deg² using spectral energy distribution (SED) model fitting to photometric data from Dark Energy Survey (g, r, i, z, Y), VISTA Hemisphere Survey (J, H, K) and Wide-field Infrared Survey Explorer (W1, W2). The photometric data were fitted with a grid of quasar model SEDs with redshift-dependent Ly α forest absorption and a range of intrinsic reddening as well as a series of low-mass cool star models. Candidates were ranked using an SED-model-based χ²-statistic, which is extendable to other future imaging surveys (e.g. LSST and Euclid). Our spectral confirmation success rate is 100 per cent 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 overrun by spurious false candidates. We also present a robust parametric redshift estimator that gives comparable accuracy to Mg II and CO-based redshift estimators. We find two z ∼ 6.2 quasars with HII near zone sizes ≤3 proper Mpc that could indicate that these quasars may be young with ages ≲106-107 years or lie in over dense regions of the IGM. The z = 6.5 quasar VDES J0224-4711 has JAB = 19.75 and is the second most luminous quasar known with z ≥ 6.5. [ABSTRACT FROM AUTHOR] |
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