J/MNRAS/428/226 High-redshift quasar candidates (Polsterer+, 2013)
Finding new high-redshift quasars by asking the neighbours.
Polsterer K.L., Zinn P.-C., Gieseke F.
<Mon. Not. R. Astron. Soc., 428, 226-235 (2013)>
=2013MNRAS.428..226P 2013MNRAS.428..226P
ADC_Keywords: QSOs ; Redshifts
Keywords: methods: statistical - techniques: photometric - catalogues -
surveys - galaxies: distances and redshifts - quasars: general
Abstract:
Quasars with 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 α 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 120000 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% and we expect 60000 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.
Description:
The presented method of photometrically selecting high-redshift quasar
candidates is based on the Sloan Digital Sky Survey Data Release 6.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
qsocand.dat 150 121909 Quasar candidate data from SDSS photometry
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See also:
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
http://www.sdss.org : SDSS Home Page
Byte-by-byte Description of file: qsocand.dat
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Bytes Format Units Label Explanations
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1- 18 I18 --- SDSS SDSS objID number
20- 37 F18.14 deg RAdeg Right ascension (J2000)
39- 56 E18.14 deg DEdeg Declination (J2000)
58- 62 F5.3 --- z [2.5/6.2] Redshift photometric estimate
64- 70 F7.5 --- e_z Standard deviation in redshift
72- 85 F14.12 --- Class [0.83/1] Coarse classifier rate (separates
quasars, galaxies and stars)
87-100 F14.12 --- Rej* [0/.471] Cool star rejection rate (separates
cool stars and quasars)
102-115 F14.12 --- Dist [0.63/1] Modified distance rate (separates
quasars, galaxies and stars)
117-122 F6.3 mag umag psf SDSS u magnitude
124-129 F6.3 mag gmag psf SDSS g magnitude
131-136 F6.3 mag rmag psf SDSS r magnitude
138-143 F6.3 mag imag psf SDSS i magnitude
145-150 F6.3 mag zmag psf SDSS z magnitude
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 03-Dec-2013