J/MNRAS/375/1349 6C** sample of steep-spectrum radio sources. II (Cruz+, 2007)
The 6C** sample of steep-spectrum radio sources -
II. Redshift distribution and the space density of high-redshift radio galaxies.
Cruz M.J., Jarvis M.J., Rawlings S., Blundell K.M.
<Mon. Not. R. Astron. Soc., 375, 1349-1363 (2007)>
=2007MNRAS.375.1349C 2007MNRAS.375.1349C
ADC_Keywords: Radio sources ; Redshifts
Keywords: galaxies: active - galaxies: evolution - quasars: general -
radio continuum: galaxies
Abstract:
We use the 6C** sample to investigate the comoving space density of
powerful, steep-spectrum radio sources. This sample, consisting of 68
objects, has virtually complete K-band photometry and spectroscopic
redshifts for 32 per cent of the sources. In order to find its
complete redshift distribution, we develop a method of redshift
estimation based on the Kz diagram of the 3CRR, 6CE, 6C* and 7CRS
radio galaxies. Based on this method, we derive redshift probability
density functions for all the optically identified sources in the 6C**
sample. Using a combination of spectroscopic and estimated redshifts,
we select the most radio luminous sources in the sample. Their
redshift distribution is then compared with the predictions of the
radio luminosity function of Jarvis et al. (2001MNRAS.327..907J 2001MNRAS.327..907J). We
find that, within the uncertainties associated with the estimation
method, the data are consistent with a constant comoving space density
of steep-spectrum radio sources beyond z>2.5, and rule out a steep
decline.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 63 68 Summary of the observational data on the 6C** sample
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See also:
VIII/18 : 6C Survey of radio sources - I. (Baldwin+ 1985)
VIII/21 : 6C Survey of radio sources - II. (Hales+ 1988)
VIII/22 : 6C Survey of Radio Sources - III. (Hales+ 1990)
VIII/23 : 6C Survey of radio sources - IV. (Hales+ 1991)
VIII/24 : 6C Survey of Radio Sources - V. (Hales+ 1993)
VIII/25 : 6C Survey of radio sources - VI. (Hales+ 1993)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
J/MNRAS/373/1531 : 6C** sample of steep-spectrum radio sources (Cruz+, 2006)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 ---- 6C Source name, 6CHHMM+DDMM (B1950)
13- 17 F5.2 Jy S151MHz 151MHz flux-density measurements (1)
19- 22 F4.2 --- SI radio spectral index evaluated between 151MHz
and 1.4GHz (2)
24 A1 --- l_Kmag Limit flag on Kmag
25- 30 F6.3 mag Kmag Kmagnitude
32 I1 --- Aper Angular aperture used for Kmag
35- 39 F5.3 --- z ? Redshift
40 A1 --- u_z [?] Uncertainty flag on z
41- 42 A2 --- n_z [nd ] no detection (3)
43- 52 A10 --- eLine Prominent emission line in the existing
spectra (4)
54- 58 F5.2 [W] Lum ? Luminosity of the emission line eLine
60- 63 A4 --- r_z Reference for the redshift (5)
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Note (1): From the 6C survey (Hales et al:, 1988, Cat. VIII/21;
Hales et al., 1990, Cat. VIII/22)
Note (2): From the 6C and NRAO VLA Sky Survey (NVSS; Condon et al. 1998,
Cat. VIII/65) flux densities (SI=-dLog(S)/dν)
Note (3): nd signifies that the source was observed but there were no emission
lines and/or continuum detected.
Note (4): ? signifies that the line identification is uncertain.
Note (5): References as follows:
Cea = Paper I, Cruz et al., 2006, Cat. J/MNRAS/373/1531
DBea = De Breuck et al. (2001AJ....121.1241D 2001AJ....121.1241D)
McC = McCarthy (1991AJ....102..518M 1991AJ....102..518M)
Vea = Vigotti et al. (1990A&AS...83..205V 1990A&AS...83..205V)
ASea = Allington-Smith, Lilly & Longair (1985MNRAS.213..243A 1985MNRAS.213..243A)
Bea = Brinkmann et al. (2000, Cat. J/A+A/356/445)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 16-Nov-2007