J/ApJ/819/24 z>4.5 QSOs with SDSS and WISE. I. Opt. spectra (Wang+, 2016)
A survey of luminous high-redshift quasars with SDSS and WISE.
I. Target selection and optical spectroscopy.
Wang F., Wu X.-B., Fan X., Yang J., Yi W., Bian F., McGreer I.D., Yang Q.,
Ai Y., Dong X., Zuo W., Jiang L., Green R., Wang S., Cai Z., Wang R.,
Yue M.
<Astrophys. J., 819, 24 (2016)>
=2016ApJ...819...24W 2016ApJ...819...24W (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Redshifts ; Photometry, SDSS ; Photometry, infrared ;
Spectroscopy
Keywords: galaxies: active; galaxies: high-redshift; quasars: emission lines;
quasars: general
Abstract:
High-redshift quasars are important tracers of structure and evolution
in the early universe. However, they are very rare and difficult to
find when using color selection because of contamination from
late-type dwarfs. High-redshift quasar surveys based on only optical
colors suffer from incompleteness and low identification efficiency,
especially at z≳4.5. We have developed a new method to select
4.7≲z≳5.4 quasars with both high efficiency and completeness by
combining optical and mid-IR Wide-field Infrared Survey Explorer
(WISE) photometric data, and are conducting a luminous z∼5 quasar
survey in the whole Sloan Digital Sky Survey (SDSS) footprint. We have
spectroscopically observed 99 out of 110 candidates with z-band
magnitudes brighter than 19.5, and 64 (64.6%) of them are quasars with
redshifts of 4.4≲z≲5.5 and absolute magnitudes of
-29≲M1450≲-26.4. In addition, we also observed 14 fainter
candidates selected with the same criteria and identified 8 (57.1%) of
them as quasars with 4.7<z<5.4. Among 72 newly identified quasars, 12
of them are at 5.2<z<5.7, which leads to an increase of ∼36% of the
number of known quasars at this redshift range. More importantly, our
identifications doubled the number of quasars with M1450←27.5 at
z>4.5, which will set strong constraints on the bright end of the
quasar luminosity function. We also expand our method to select
quasars at z≳5.7. In this paper we report the discovery of four new
luminous z≳5.7 quasars based on SDSS-WISE selection.
Description:
Optical spectroscopic observations to identify these quasar candidates
were carried out using several facilities: the Lijiang 2.4m telescope
(LJT) and the Xinglong 2.16m telescope in China; the Kitt Peak 2.3m
Bok telescope and the 6.5m MMT telescope in the U.S.; and the 2.3m ANU
telescope in Australia.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 101 725 Optical and WISE photometry of 725 published
z>4.5 quasars
table2.dat 60 72 Observational information of 72 newly identified
z∼5 quasars
table3.dat 95 72 Photometric properties of 72 new identified
z∼5 quasars
refs.dat 81 70 References
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See also:
VII/270 : SDSS quasar catalog: tenth data release (Paris+, 2014)
II/328 : AllWISE Data Release (Cutri+ 2013)
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
II/311 : WISE All-Sky Data Release (Cutri+ 2012)
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
VII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)
VII/258 : Quasars and Active Galactic Nuclei (13th Ed.) (Veron+ 2010)
VII/241 : The 2dF QSO Redshift Survey (Croom+ 2004)
J/ApJS/219/39 : QSOs selection from SDSS and WISE (Richards+, 2015)
J/MNRAS/450/3893 : SDSS DR10 catalogue of candidate quasars (Brescia+, 2015)
J/A+A/583/A75 : Large Quasar Astrometric Catalogue 3 (LQAC-3) (Souchay+, 2015)
J/ApJ/768/105 : z∼5 QSO LF from SDSS Stripe 82 (McGreer+, 2013)
J/AJ/144/49 : Quasars from SDSS-DR7, WISE and UKIDSS surveys (Wu+, 2012)
J/ApJS/200/8 : AGES: the AGN and Galaxy Evolution Survey (Kochanek+, 2012)
J/ApJS/197/19 : First brown dwarfs discovered by WISE (Kirkpatrick+, 2011)
J/ApJS/194/45 : QSO properties from SDSS-DR7 (Shen+, 2011)
J/ApJ/699/782 : High-redshift SDSS-DR5 QSOs (Diamond-Stanic+, 2009)
J/ApJS/166/470 : SDSS-Spitzer type I QSOs IR photometry (Richards+, 2006)
J/ApJ/640/579 : Near-infrared spectra of 27 SDSS quasars (Glikman+, 2006)
J/AJ/122/503 : QSO SDSS u*g*r*i*z* photometry & redshifts (Anderson+, 2001)
J/AJ/121/31 : High-redshift quasars in SDSS (Fan+, 2001)
http://www.sdss3.org/ : SDSS-III home page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 20 A20 --- Name Source identifier (JHHMMSS.ss+DDMMSS.ss)
22- 26 F5.3 --- z [4.5/7.1] Spectroscopic redshift from discovery
paper
28- 32 A5 --- Ref1 References of discovery paper (see refs.dat file)
34- 38 F5.2 mag rmag [18.2/27.6]?=99 SDSS corrected r-band magnitude (1)
40- 44 F5.2 mag e_rmag [0.01/1.6]?=99 Error in rmag
46- 50 F5.2 mag imag [17.2/28]?=99 SDSS corrected i-band magnitude (1)
52- 56 F5.2 mag e_imag [0.01/2.2]?=99 Error in imag
58- 62 F5.2 mag zmag [17.4/26]?=99 SDSS corrected z-band magnitude (1)
64- 68 F5.2 mag e_zmag [0.01/1.1]?=99 Error in zmag
70- 73 A4 --- Ref2 Reference for optical magnitudes ("SDSS" or "REF")
75- 79 F5.2 mag W1mag [13.5/19]?=99 WISE W1-band (3.4um) magnitude
81- 85 F5.2 mag e_W1mag [0.03/0.6]?=99 Error in W1mag
87- 91 F5.2 mag W2mag [13.1/17.6]?=99 WISE W2-band (4.6um) magnitude
93- 97 F5.2 mag e_W2mag [0.03/0.6]?=99 Error in W2mag
99-101 A3 --- Ref3 Reference for WISE magnitude (2)
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Note (1): Most optical magnitudes are from the SDSS DR10 photometric catalog
and are Galactic extinction corrected SDSS PSF asinh magnitudes
(zAB=zSDSS+0.02mag). The optical magnitudes come from the
reference paper and are in the AB system, if the quasar does not
have SDSS DR 10 photometry.
Note (2): This table only includes quasars that were published before July 2015.
Reference as follows:
AW = ALLWISE catalog;
AWR = ALLWISE Reject catalog;
AS = ALL-SKY WISE catalog;
ASR = ALL-SKY WISE Reject catalog;
99 = no detection in any WISE catalog.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 20 A20 --- Name Source identifier (JHHMMSS.ss+DDMMSS.ss) (G1)
22- 28 A7 --- Tel Telescope code (2)
30- 35 A6 --- Grating Grating used on Tel
37- 39 F3.1 arcsec Slit [1/2.5] Slit width
41- 44 F4.2 --- z [4.4/5.6] Spectroscopic redshift
46- 55 A10 "Y/M/D" Date UT date of the observation
57- 60 I4 s Exp [200/3600] Exposure time
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Note (2): Telescope code as follows:
ANU = 2.3m ANU telescope.
LJT = Lijiang 2.4m telescope.
MMT = 6.5m MMT telescope.
216 = Xing-long 2.16m telescope.
Bok = Kitt Peak 2.3m Bok telescope.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 20 A20 --- Name Source identifier (JHHMMSS.ss+DDMMSS.ss) (G1)
22 A1 --- f_Name [a] Flag on Name (1)
24- 27 F4.2 --- z [4.4/5.6] Spectroscopic redshift
29- 33 F5.2 mag m1450 [17.5/20.3] Apparent 1450Å AB magnitude (2)
35- 40 F6.2 mag M1450 [-29/-26] Absolute 1450Å AB magnitude (2)
42- 46 F5.2 mag rmag [19.5/22.5] SDSS r-band AB magnitude
48- 51 F4.2 mag e_rmag [0.02/0.3] Error in rmag
53- 57 F5.2 mag imag [17.9/20.5] SDSS i-band AB magnitude
59- 62 F4.2 mag e_imag [0.01/0.05] Error in imag
64- 68 F5.2 mag zmag [17.4/20.1] SDSS z-band AB magnitude
70- 73 F4.2 mag e_zmag [0.02/0.2] Error in zmag
75- 79 F5.2 mag W1mag [14.3/17] WISE W1-band (3.4um) magnitude
81- 84 F4.2 mag e_W1mag [0.03/0.3] Error in W1mag
86- 90 F5.2 mag W2mag [13.4/16.2] WISE W2-band (4.6um) magnitude
92- 95 F4.2 mag e_W2mag [0.03/0.2] Error in W2mag
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Note (1):
a = This quasar was also independently discovered by SDSS DR12
(Paris et al. 2015, in prep).
Note (2): The apparent and absolute magnitudes were calculated by fitting a
power-law continuum fν~ναν to the spectrum of
each quasar. As many spectra of our newly discovered quasars do not
have enough continuum coverage to reliably measure the slopes of the
continua, we assumed that the slope is consistent with the average
quasar UV continuum slope αν=-0.5
(Vanden Berk et al. 2001AJ....122..549V 2001AJ....122..549V). The power-law
continuum was then normalized to match visually identified continuum
windows that contain minimal contribution from quasar emission lines
and from sky OH lines.
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Ref Reference code
6- 24 A19 --- BibCode Bibcode of the reference
26- 81 A56 --- Comm Comment
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Global notes:
Note (G1): The last 8 sources are from the fainter supplementary sample while
the rest are from the main sample.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 12-May-2016