TY - JOUR

T1 - Finding new high-redshift quasars by asking the neighbours

AU - Polsterer, Kai Lars

AU - Zinn, Peter Christian

AU - Gieseke, Fabian

PY - 2013

Y1 - 2013

N2 - Quasarswith a high redshift (z) are important to understand the evolution processes of galaxies in the early Universe. However, only a few of these distant objects are known to this date. The costs of building and operating a 10-m class telescope limit the number of facilities and, thus, the available observation time. Therefore, an efficient selection of candidates is mandatory. This paper presents a new approach to select quasar candidates with high redshift (z > 4.8) based on photometric catalogues. We have chosen to use the z > 4.8 limit for our approach because the dominant Lyman a emission line of a quasar can only be found in the Sloan i- and z-band filters. As part of the candidate selection approach, a photometric redshift estimator is presented, too. Three of the 120 000 generated candidates have been spectroscopically analysed in follow-up observations and a new z = 5.0 quasar was found. This result is consistent with the estimated detection ratio of about 50 per cent and we expect 60 000 high-redshift quasars to be part of our candidate sample. The created candidates are available for download at MNRAS or at http://www.astro.rub.de/polsterer/quasar-candidates.csv.

AB - Quasarswith a high redshift (z) are important to understand the evolution processes of galaxies in the early Universe. However, only a few of these distant objects are known to this date. The costs of building and operating a 10-m class telescope limit the number of facilities and, thus, the available observation time. Therefore, an efficient selection of candidates is mandatory. This paper presents a new approach to select quasar candidates with high redshift (z > 4.8) based on photometric catalogues. We have chosen to use the z > 4.8 limit for our approach because the dominant Lyman a emission line of a quasar can only be found in the Sloan i- and z-band filters. As part of the candidate selection approach, a photometric redshift estimator is presented, too. Three of the 120 000 generated candidates have been spectroscopically analysed in follow-up observations and a new z = 5.0 quasar was found. This result is consistent with the estimated detection ratio of about 50 per cent and we expect 60 000 high-redshift quasars to be part of our candidate sample. The created candidates are available for download at MNRAS or at http://www.astro.rub.de/polsterer/quasar-candidates.csv.

KW - Distances and redshifts-quasars

KW - General

KW - methods: Statistical-techniques

KW - Photometric-catalogues-surveys-galaxies

U2 - 10.1093/mnras/sts017

DO - 10.1093/mnras/sts017

M3 - Journal article

AN - SCOPUS:84872415771

VL - 428

SP - 226

EP - 235

JO - Royal Astronomical Society. Monthly Notices

JF - Royal Astronomical Society. Monthly Notices

SN - 0035-8711

IS - 1

ER -