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Title: 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.
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Publication Date:
Report Number(s):
FERMILAB-PUB-16-570-AE-PPD; arXiv:1701.04852
Journal ID: ISSN 0035-8711; 1509489
Grant/Contract Number:
AC02-07CH11359; AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Volume: 468; Journal Issue: 4; Journal ID: ISSN 0035-8711
Publisher:
Royal Astronomical Society
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Orgs:
DES; WISE; VISTA
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; galaxies: active; galaxies: formation; galaxies: high redshift; quasars individual: VDES J0224−4711; dark ages; reionization; first stars
OSTI Identifier:
1361377
Alternate Identifier(s):
OSTI ID: 1343963

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., Carretero, J., da Costa, L. N., DePoy, D. L., Desai, S., Diehl, H. T., Doel, P., Evrard, A. E., Finley, D. A., Flaugher, B., Fosalba, P., Frieman, J., García-Bellido, J., Gaztanaga, E., Goldstein, D. A., Gruen, D., Gruendl, R. A., Gutierrez, G., James, D. J., Kuehn, K., Kuropatkin, N., Lahav, O., Lima, M., Maia, M. A. G., Marshall, J. L., Melchior, P., Miller, C. J., Miquel, R., Nord, B., Ogando, R., Plazas, A. A., Romer, A. K., Sanchez, E., Scarpine, V., Schubnell, M., Sevilla-Noarbe, I., Smith, R. C., Sobreira, F., Suchyta, E., Swanson, M. E. C., Tarle, G., Tucker, D. L., Walker, A. R., and Wester, W.. Eight new luminous z ≥ 6 quasars discovered via SED model fitting of VISTA, WISE and Dark Energy Survey Year 1 observations. United States: N. p., Web. doi:10.1093/mnras/stx728.
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., Carretero, J., da Costa, L. N., DePoy, D. L., Desai, S., Diehl, H. T., Doel, P., Evrard, A. E., Finley, D. A., Flaugher, B., Fosalba, P., Frieman, J., García-Bellido, J., Gaztanaga, E., Goldstein, D. A., Gruen, D., Gruendl, R. A., Gutierrez, G., James, D. J., Kuehn, K., Kuropatkin, N., Lahav, O., Lima, M., Maia, M. A. G., Marshall, J. L., Melchior, P., Miller, C. J., Miquel, R., Nord, B., Ogando, R., Plazas, A. A., Romer, A. K., Sanchez, E., Scarpine, V., Schubnell, M., Sevilla-Noarbe, I., Smith, R. C., Sobreira, F., Suchyta, E., Swanson, M. E. C., Tarle, G., Tucker, D. L., Walker, A. R., & Wester, W.. Eight new luminous z ≥ 6 quasars discovered via SED model fitting of VISTA, WISE and Dark Energy Survey Year 1 observations. United States. doi:10.1093/mnras/stx728.
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., Carretero, J., da Costa, L. N., DePoy, D. L., Desai, S., Diehl, H. T., Doel, P., Evrard, A. E., Finley, D. A., Flaugher, B., Fosalba, P., Frieman, J., García-Bellido, J., Gaztanaga, E., Goldstein, D. A., Gruen, D., Gruendl, R. A., Gutierrez, G., James, D. J., Kuehn, K., Kuropatkin, N., Lahav, O., Lima, M., Maia, M. A. G., Marshall, J. L., Melchior, P., Miller, C. J., Miquel, R., Nord, B., Ogando, R., Plazas, A. A., Romer, A. K., Sanchez, E., Scarpine, V., Schubnell, M., Sevilla-Noarbe, I., Smith, R. C., Sobreira, F., Suchyta, E., Swanson, M. E. C., Tarle, G., Tucker, D. L., Walker, A. R., and Wester, W.. 2017. "Eight new luminous z ≥ 6 quasars discovered via SED model fitting of VISTA, WISE and Dark Energy Survey Year 1 observations". United States. doi:10.1093/mnras/stx728. https://www.osti.gov/servlets/purl/1361377.
@article{osti_1361377,
title = {Eight new luminous z ≥ 6 quasars discovered via SED model fitting of VISTA, WISE and Dark Energy Survey Year 1 observations},
author = {Reed, S. L. and McMahon, R. G. and Martini, P. and Banerji, M. and Auger, M. and Hewett, P. C. and Koposov, S. E. and Gibbons, S. L. J. and Gonzalez-Solares, E. and Ostrovski, F. and Tie, S. S. and Abdalla, F. B. and Allam, S. and Benoit-Lévy, A. and Bertin, E. and Brooks, D. and Buckley-Geer, E. and Burke, D. L. and Carnero Rosell, A. and Carrasco Kind, M. and Carretero, J. and da Costa, L. N. and DePoy, D. L. and Desai, S. and Diehl, H. T. and Doel, P. and Evrard, A. E. and Finley, D. A. and Flaugher, B. and Fosalba, P. and Frieman, J. and García-Bellido, J. and Gaztanaga, E. and Goldstein, D. A. and Gruen, D. and Gruendl, R. A. and Gutierrez, G. and James, D. J. and Kuehn, K. and Kuropatkin, N. and Lahav, O. and Lima, M. and Maia, M. A. G. and Marshall, J. L. and Melchior, P. and Miller, C. J. and Miquel, R. and Nord, B. and Ogando, R. and Plazas, A. A. and Romer, A. K. and Sanchez, E. and Scarpine, V. and Schubnell, M. and Sevilla-Noarbe, I. and Smith, R. C. and Sobreira, F. and Suchyta, E. and Swanson, M. E. C. and Tarle, G. and Tucker, D. L. and Walker, A. R. and Wester, W.},
abstractNote = {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.},
doi = {10.1093/mnras/stx728},
journal = {Monthly Notices of the Royal Astronomical Society},
number = 4,
volume = 468,
place = {United States},
year = {2017},
month = {3}
}