J/MNRAS/328/150 KX redshift survey (Croom+, 2001)
A small-area faint KX redshift survey for QSOs in the
ESO Imaging Survey Chandra Deep Field South.
Croom S.M., Warren S.J., Glazebrook K.
<Mon. Not. R. Astron. Soc. 328, 150 (2001)>
=2001MNRAS.328..150C 2001MNRAS.328..150C
ADC_Keywords: X-ray sources ; Redshifts ; QSOs ; Galaxies, IR ;
Galaxies, photometry
Keywords: surveys - galaxies: active - quasars: general - infrared: galaxies
Abstract:
In this paper we present preliminary spectroscopic results from a
small-area faint K-excess (KX) survey, and compare KX selection
against UVX selection. The aim of the KX method is to produce complete
samples of QSOs that are flux-limited in the K band, in order to
minimize any selection bias in samples of QSOs from the effects of
reddening and extinction. Using the photometric catalogue of the ESO
Imaging Survey Chandra Deep Field South (48arcmin2) we have
identified compact objects with J-K colours redder than the stellar
sequence that are brighter than K=19.5. We have obtained spectra of 33
candidates, using the LDSS++ spectrograph on the Anglo-Australian
Telescope (AAT). Amongst the 11 bluer candidates, with V-J<3, three
are confirmed as QSOs. Identification of the 22 redder candidates with
V-J≥3 is substantially incomplete, but so far no reddened QSOs have
been found. Near-infrared spectroscopy will be more effective in
identifying some of these targets. Only two UVX (U-B←0.2) sources
brighter than K=19.5 are found that are not also KX selected. These
are both identified as galactic stars. Thus KX selection appears to
select all UVX QSOs. The surface density of QSOs in the blue subsample
(V-J<3) at K≤19.5 is 325+136-177°-2. Because identification
of the red subsample (V-J≥3) is substantially incomplete, the
2σ upper limit on the density of reddened QSOs is large,
<1150°-2. As anticipated, at these faint magnitudes the KX
sample includes several compact galaxies. Of the 14 with measured
redshifts, there are roughly equal numbers of early- and late-type
objects. Nearly all the early-type galaxies are found in a single
structure at z=0.66.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 131 13 KX-selected objects and spectroscopic
identifications for the blue subsample, V-J≤3.0
table2.dat 117 41 KX-selected objects and spectroscopic
identifications for the red subsample, V-J>3.0
table3.dat 68 2 The two UVX non-KX sources with K≤19.5 in our
survey area
table4.dat 129 16 K≤19 galaxies observed in addition to our KX survey
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See also:
J/A+A/379/740 : ESO Imaging Survey (Arnouts+, 2001)
J/A+A/377/442 : Chandra Deep Field South: R-band photometry (Wolf+, 2001)
J/A+A/375/1 : IR obs. of Chandra Deep Field + HDF-South (Saracco+, 2001)
J/AJ/122/2810 : Chandra Deep Field North Survey. V. (Brandt+, 2001)
J/ApJ/554/742 : Chandra Deep Survey of the HDF-N (Hornschemeier+, 2001)
Byte-by-byte Description of file: table?.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- [CWG2001] Designation (1)
6 I1 h RAh Right ascension (J2000.0)
8- 9 I2 min RAm Right ascension (J2000.0)
11- 15 F5.2 s RAs Right ascension (J2000.0)
17 A1 --- DE- Declination sign (J2000.0)
18- 19 I2 deg DEd Declination (J2000.0)
21- 22 I2 arcmin DEm Declination (J2000.0)
24- 27 F4.1 arcsec DEs Declination (J2000.0)
29- 33 F5.2 mag Umag ? Bessel U magnitude
35- 39 F5.2 mag Bmag ? Bessel B magnitude
41- 45 F5.2 mag Vmag ? Bessel V magnitude
47- 51 F5.2 mag Rmag ? Bessel R magnitude
53- 57 F5.2 mag Jmag J magnitude
59- 63 F5.2 mag Kmag K magnitude
65- 68 F4.2 --- S/GK K-band SExtractor stellarity parameter
(star=1, galaxy=0)
70- 74 F5.3 --- z ? Redshift
76- 81 A6 --- Type Type of object (Gal or QSO) (2)
83-131 A49 --- Lines Spectral features, both absorption
and emission
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Note (1): Designations:
KX NN for tables 1 and 2
UVXN for table 3
KG NN for table 4
Note (2): An (e) or (a) after gal denotes emission- or absorption-
dominated spectra respectively; an "?" indicates that the type
could not be identified from the spectra.
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History:
Prepared via OCR at CDS.
(End) James Marcout, Patricia Bauer [CDS] 31-Jan-2002