J/ApJS/184/218 The zCOSMOS 10k-bright spectroscopic sample (Lilly+, 2009)
The zCOSMOS 10k-Bright spectroscopic sample.
Lilly S.J., Le Brun V., Maier C., Mainieri V., Mignoli M., Scodeggio M.,
Zamorani G., Carollo M., Contini T., Kneib J.-P., Le Fevre O., Renzini A.,
Bardelli S., Bolzonella M., Bongiorno A., Caputi K., Coppa G., Cucciati O.,
De La Torre S., De Ravel L., Franzetti P., Garilli B., Iovino A.,
Kampczyk P., Kovac K., Knobel C., Lamareille F., Le Borgne J.-F., Pello R.,
Peng Y., Perez-Montero E., Ricciardelli E., Silverman J.D., Tanaka M.,
Tasca L., Tresse L., Vergani D., Zucca E., Ilbert O., Salvato M., Oesch P.,
Abbas U., Bottini D., Capak P., Cappi A., Cassata P., Cimatti A., Elvis M.,
Fumana M., Guzzo L., Hasinger G., Koekemoer A., Leauthaud A., Maccagni D.,
Marinoni C., McCracken H., Memeo P., Meneux B., Porciani C., Pozzetti L.,
Sanders D., Scaramella R., Scarlata C., Scoville N., Shopbell P.,
Taniguchi Y.
<Astrophys. J. Suppl. Ser., 184, 218-229 (2009)>
=2009ApJS..184..218L 2009ApJS..184..218L
ADC_Keywords: Redshifts ; Galaxies, optical ; Magnitudes ; Active gal. nuclei
Surveys
Keywords: cosmology: observations - galaxies: active -
galaxies: distances and redshifts - galaxies: evolution -
large-scale structure of universe - quasars: general - surveys
Abstract:
We present spectroscopic redshifts of a large sample of galaxies with
IAB<22.5 in the COSMOS field, measured from spectra of 10644 objects
that have been obtained in the first two years of observations in the
zCOSMOS-bright redshift survey. These include a statistically complete
subset of 10109 objects. The average accuracy of individual redshifts
is 110km/s, independent of redshift. The reliability of individual
redshifts is described by a Confidence Class that has been empirically
calibrated through repeat spectroscopic observations of over 600
galaxies. There is very good agreement between spectroscopic and
photometric redshifts for the most secure Confidence Classes. For the
less secure Confidence Classes, there is a good correspondence between
the fraction of objects with a consistent photometric redshift and the
spectroscopic repeatability, suggesting that the photometric redshifts
can be used to indicate which of the less secure spectroscopic
redshifts are likely right and which are probably wrong, and to give
an indication of the nature of objects for which we failed to
determine a redshift. Using this approach, we can construct a
spectroscopic sample that is 99% reliable and which is 88% complete in
the sample as a whole, and 95% complete in the redshift range
0.5<z<0.8. The luminosity and mass completeness levels of the
zCOSMOS-bright sample of galaxies is also discussed.
Description:
Observations for the 10k sample were carried out with the VIMOS
spectrograph mounted on the 8m VLT/UT3 telescope during extensive
Service Mode runs in 2005 and 2006.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 47 10644 zCOSMOS-bright 10k sample
--------------------------------------------------------------------------------
See also:
J/ApJS/172/70 : zCOSMOS-bright catalog (Lilly+, 2007)
J/A+A/510/A56 : zCOSMOS type-2 AGN (Bongiorno, 2010)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- zCOSMOS zCOSMOS identification number
8- 17 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000)
19- 26 F8.6 deg DEdeg Declination in decimal degrees (J2000)
28- 33 F6.4 --- z ?=9.9999 Spectroscopic redshift
35- 39 F5.1 --- CClass Confidence class indicating reliability (1)
41- 45 F5.2 mag Imag HST F814W filter selection AB magnitude
47 I1 --- Mask Mask priority flag (2)
--------------------------------------------------------------------------------
Note (1): The Confidence Class is made of a number and a decimal modifier.
* Confidence number:
4 = a very secure redshift with an exhibition-quality spectrum
3 = a very secure redshift
2 = a likely redshift about which there is some doubt
9 = a securely detected line which is believed to be
either [OII]3727 or Hα6563
1 = an insecure redshift
0 = no redshift measurement attempted
10 = as above but for broad line AGN; with 18 instead of 9,
reflecting the greater range of possibilities
20 = As above but for a target only observed as a
secondary target in a slit centered on another object
200 = 20
* Decimal place modifiers:
.5 = The spectroscopic and photometric redshifts are consistent
to within 0.08(1+z)
.4 = No photometric redshift is available for some reason
.3 = For Class 9 and 18 one-line redshifts only, the spectroscopic
redshift is consistent only after the spectroscopic redshift
is changed to the alternate redshift
.1 = The spectroscopic and photometric redshifts differ by
more than 0.08(1+z)
The set of objects defined as Classes 1.5, 2.4, 2.5, 9.3, 9.5 and all
Class 3.x and 4.x comprise 88% of the sample (95% between 0.5<z<0.8)
and are estimated to be 99% reliable. The redshifts with Classes 1.1,
2.1 and 9.1 (and 21.1, 22.1 and 29.1) are likely to be incorrect and
should not be used, even though they are retained in the catalogue for
completeness. See section 2.2.2 for further explanation.
Note (2): The mask priority indicates the priority for insertion in the
slit masks as follows:
1 = a randomly selected object from the main catalog
2 = a "compulsory target" that has a roughly twice higher chance
of having been observed
0 = an object that was not intended to be observed (e.g. because it
was thought to be a star) but in fact was observed, usually as
a secondary object in the slit of another target.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 15-Feb-2010