J/ApJ/644/100 SDSS quasars in the COSMOS field (Prescott+, 2006)
Quasars in the COSMOS field.
Prescott M.K.M., Impey C.D., Cool R.J., Scoville N.Z.
<Astrophys. J., 644, 100-115 (2006)>
=2006ApJ...644..100P 2006ApJ...644..100P
ADC_Keywords: Surveys ; QSOs ; Redshifts
Keywords: quasars: emission lines - quasars: general - surveys
Abstract:
We obtained medium-resolution spectra of 336 quasar candidates in
the COSMOS HST Treasury field using the MMT 6.5m telescope and the
Hectospec multiobject spectrograph. Candidates were drawn from the
Sloan Digital Sky Survey (SDSS) DR1 catalog using quasar flags set by
the SDSS multicolor quasar target selection algorithm. In this paper
we present our discovery spectra from 1.39deg2 (69.5% of the COSMOS
field) and a discussion of the selection method and yields. We
confirmed 95 quasars, including at least two BAL quasars; 80 of these
are new quasars that do not appear in previous quasar confirmation
follow-up studies. The candidates additionally included 184 compact
emission-line galaxies, a third of which are likely type 2 AGNs, and
12 stars. The quasars span a range in magnitude of 18.3<g<22.5 and a
range in redshift of 0.2<z<2.3. Our results are consistent with a
lower limit quasar surface density from SDSS color selection of
102deg-2 down to g=22.5 over the entire COSMOS field. This work is
the first step toward the eventual goal of setting up a grid of quasar
absorption line probes of the 2deg2 field and of conducting a
complete census of supermassive black holes in this well-studied
survey region. The total quasar count at the conclusion of this study
is 139, making COSMOS one of the most densely sampled regions of sky
where a grid of quasar sight lines can be used to probe the
intervening volume.
Description:
Observations were carried out during the night of 2004 April 18 using
the MMT 6.5m telescope and the Hectospec multiobject spectrograph.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 74 291 Spectroscopically-Confirmed Targets in the
COSMOS Field
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See also:
J/A+A/468/937 : K-band AO imaging in COSMOS deep field (Huertas-Company+, 2007)
http://www.sdss.org : SDSS Home Page
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SDSS]
6- 24 A19 --- SDSS Source name (JHHMMSS.ss+DDMMSS.s)
26- 27 I2 h RAh Hour of Right Ascension (J2000)
29- 30 I2 min RAm Minute of Right Ascension (J2000)
32- 36 F5.2 s RAs Second of Right Ascension (J2000)
37 A1 --- DE- Sign of Declination (J2000)
38 I1 deg DEd Degree of Declination (J2000)
40- 41 I2 arcmin DEm Arcminute of Declination (J2000)
43- 47 F5.2 arcsec DEs Arcsecond of Declination (J2000)
49- 54 A6 --- Class Classification (qso, galaxy, star)
56- 63 F8.6 --- z ? Redshift
65 A1 --- n_z [bcd] Note on z (1)
67- 74 F8.6 --- e_z ? Error in z (2)
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Note (1): Notes are as follows:
b = Redshift determined using a flux-weighted mean line centroid.
Redshift errors are Δz∼0.002 or less.
c = BAL quasar with uncertain redshift.
d = Independently confirmed by the 2dF quasar survey or subsequent
SDSS spectroscopic follow-up.
Note (2): Redshift errors are formal errors returned by χ2
template-fitting procedure, and may be underestimates in the case
of systematic shifts according to line species (Richards et al.,
2002AJ....123.2945R 2002AJ....123.2945R; McIntosh et al., 1999ApJ...517L..73M 1999ApJ...517L..73M;
Tytler & Fan, 1992ApJS...79....1T 1992ApJS...79....1T).
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 30-Aug-2007