J/PAZh/42/313 3XMM-DR4 QSO candidates at 3<z<5.5 (Khorunzhev+, 2016)
Catalog of quasar candidates at 3<z<5.5 selected from the 3XMM-DR4 X-ray
source catalog.
Khorunzhev G.A., Burenin R.A., Mescheryakov A.V., Sazonov S.Yu.
<Pis'ma Astron. Zh. 42, 313 (2016)>
=2016PAZh...42..313K 2016PAZh...42..313K (SIMBAD/NED BibCode)
=2016AstL...42..277K 2016AstL...42..277K
ADC_Keywords: X-ray sources ; QSOs ; Redshifts ; Photometry, SDSS
Keywords: active galactic nuclei - X-ray surveys -
photometric quasar redshift estimates
Abstract:
A catalog of quasar candidates at redshifts 3<z<5.5 is presented.
These candidates have been selected among X-ray sources in the
XMM-Newton Serendipitous Source Catalog (3XMM-DR4) in the 0.5-2keV
band, located at high galactic latitudes |b|>20deg in the Sloan
Digital Sky Survey (SDSS) area. The total overlapping area is about
300 sq. deg. The SDSS, 2MASS and WISE photometric catalogs were used.
Only SDSS point sources were considered. X-ray sources having an
optical counterpart with magnitude error in SDSS z band of less than
0.2 and color i-z<0.6 were chosen. Their photometric redshifts were
determined with the EAZY code using a library of spectral templates. A
sample of quasar candidates with photometric redshifts in the range
2.75<z<5.5 has been composed. Objects whose spectral energy
distributions are better described by stellar templates have been
excluded. The selection completeness of known quasars is about 80%.
The normalized median absolute deviation of the differences between
the photometric and spectroscopic redshifts of known quasars is 0.07
(with 9% outliers). The sky density of quasar candidates in our sample
is 1.5 times that of the spectroscopic SDSS sample in the same fields.
Follow-up spectroscopy should clarify the purity of the sample.
Description:
The catalog of X-ray selected (3XMM-DR4) quasar candidates with
photometric redshifts 2.75<z<5.5. The photometric redshifts have been
determined using SDSS, 2MASS and WISE photometry. Known spectroscopic
redshifts from the Half Million Quasars catalogue (Flesch, 2015, Cat.
VII/273) and the SDSS spectroscopic programm (Alam et al.,
2015ApJS..219...12A 2015ApJS..219...12A) are also included. table1.dat lists objects with
photometric redshifts 2.7<z5.5. table2.dat lists known spectroscopic
z>3 quasars from 3XMM-DR4 that have not been selected by our
algorithm.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 112 903 Catalog of 3<z<5.5 quasar candidates
table2.dat 112 63 List of known quasars at z>3 not selected by
our algorithm
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See also:
IX/44 : XMM-Newton Serend. Source Catalogue 3XMM-DR4 (XMM-SSC, 2013)
IX/46 : XMM-Newton Serend. Source Catalogue 3XMM-DR5 (XMM-SSC, 2016)
VII/273 : The Half Million Quasars (HMQ) catalogue (Flesch, 2015)
J/PASP/110/863 : A Stellar Spectral Flux Library: 1150-25000Å (Pickles 1998)
Byte-by-byte Description of file: table1.dat table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- N Index number, within the table
5- 20 A16 --- Name 3XMM Source name in 3XMM-DR4
23- 28 I6 --- SRCID Source number in 3XMM-DR4
31- 38 F8.4 deg RAdeg Right ascension J2000 (degrees)
41- 48 F8.4 deg DEdeg Declination J2000 (degrees)
50- 55 F6.3 10aW/m2 FX05-2 X-ray flux in 0.5-2keV (10-14erg/s/cm2)
57- 62 F6.3 10aW/m2 e_FX05-2 Error on flux in 0.5-2keV (10-14erg/s/cm2)
64- 68 F5.2 mag ipmag SDSS (AB) PSF magnitude in i' band
70- 74 F5.2 mag zpmag SDSS (AB) PSF magnitude in z' band
76- 80 F5.3 --- zspec ? Spectroscopic redshift
83 I1 --- r_zspec [0/1]? Reference for spectroscopic
redshift (1)
84 A1 --- --- [(]
85- 88 I4 --- Flag ? zWarning for zref=0 or reference number
from HMQ (Cat. VII/273) for zref=1 (1)
89 A1 --- --- [)]
91- 94 F4.2 --- zphot Photometric redshift
96- 99 A4 --- FL Photometric data flag (2)
101-102 I2 --- TQ Best quasar template (3)
104-109 A6 --- TS Best star template (4)
111-112 I2 --- NBand Number of bands with reliable photometry
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Note (1): Reference on zspec as follows:
0 = SDSS spectroscopic redshift (with zWarning flag in brackets)
1 = The Half Million Quasars redshift
(with reference paper number from Flesch (2015PASA...32...10F 2015PASA...32...10F,
Cat. VII/273) in brackets)
Note (2): Photometric data flag as follows:
t = object was an observation target of XMM-Newton
r = star template from Pickles (1998, Cat. J/PASP/110/863/) that describes
photometric data better than quasar template
G = extended object in SDSS
D = ambiguous optical counterpart near the X-ray source
w = photometric redshift has been estimated from SDSS data only, although
there is a nearby WISE source
Note (3): Reference number in the quasar template library
Note (4): Best template from the star template library of Pickles
(1998, Cat. J/PASP/110/863/)
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Acknowledgements:
George Khorunzhev, horge(at)iki.rssi.ru
Sergey Sazonov, sazonov(at)iki.rssi.ru
(End) Patricia Vannier [CDS] 10-Mar-2016