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J/MNRAS/438/796     Local radio-galaxy population at 20GHz  (Sadler+, 2014)

The local radio-galaxy population at 20GHz. Sadler E.M., Ekers R.D., Mahony E.K., Mauch T., Murphy T. <Mon. Not. R. Astron. Soc., 438, 796-824 (2014)> =2014MNRAS.438..796S (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Galaxies, radio Keywords: catalogues - surveys - galaxies: active - radio continuum: galaxies - radio continuum: general Abstract: We have made the first detailed study of the high-frequency radio-source population in the local Universe, using a sample of 202 radio sources from the Australia Telescope 20GHz (AT20G) survey identified with galaxies from the 6dF Galaxy Survey (6dFGS). The AT20G-6dFGS galaxies have a median redshift of z=0.058 and span a wide range in radio luminosity, allowing us to make the first measurement of the local radio luminosity function at 20GHz. Our sample includes some classical Fanaroff-Riley type I (FR I) and FR II radio galaxies, but most of the AT20G-6dFGS galaxies host compact (FR 0) radio active galactic nuclei which appear to lack extended radio emission even at lower frequencies. Most of these FR 0 sources show no evidence for relativistic beaming, and the FR 0 class appears to be a mixed population which includes young compact steep-spectrum and gigahertz peaked-spectrum radio galaxies. We see a strong dichotomy in the Wide-field Infrared Survey Explorer (WISE) mid-infrared colours of the host galaxies of FR I and FR II radio sources, with the FR I systems found almost exclusively in WISE 'early-type' galaxies and the FR II radio sources in WISE 'late-type' galaxies. The host galaxies of the flat- and steep-spectrum radio sources have a similar distribution in both K-band luminosity and WISE colours, though galaxies with flat-spectrum sources are more likely to show weak emission lines in their optical spectra. We conclude that these flat-spectrum and steep-spectrum radio sources mainly represent different stages in radio-galaxy evolution, rather than beamed and unbeamed radio-source populations. Description: We assembled the galaxy sample studied in this paper by matching radio sources from the AT20G survey catalogue (Murphy et al. 2010, Cat. J/MNRAS/402/2403) with nearby galaxies from the Third Data Release of the 6dF Galaxy Survey (6dFGS DR3; Jones et al., 2009, Cat. VII/259). The 6dFGS was chosen because it is a large-area survey well matched to the area covered by AT20G, and shallow enough in redshift that the effects of cosmic evolution within the sample volume can be neglected. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table3.dat 157 202 6dFGS galaxies detected as AT20G radio sources.
See also: VII/250 : 2dF Galaxy Redshift Survey (2dFGRS) (2dFGRS Team, 1998-2003) VIII/78 : Sydney University Molonglo Sky Survey (SUMSS) (Mauch+ 2006) VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998) J/MNRAS/329/227 : 2dF Galaxy Redshift Survey. II. (Sadler+, 2002) J/MNRAS/375/931 : Radio sources in the 6dFGS (Mauch+, 2007) J/MNRAS/402/2403 : Australia Tel. 20GHz Survey Catalog, AT20G (Murphy+, 2010) Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1 A1 --- n_Name [ab] Note on Sources (1) 3- 16 A14 --- Name Source name from the AT20G catalogue (2) 19- 20 I2 h RAh Right ascension (J2000) (3) 22- 23 I2 min RAm Right ascension (J2000) (3) 25- 29 F5.2 s RAs Right ascension (J2000) (3) 32 A1 --- DE- Declination sign (J2000) (3) 33- 34 I2 deg DEd Declination (J2000) (3) 36- 37 I2 arcmin DEM Declination (J2000) (3) 39- 42 F4.1 arcsec DEm Declination (J2000) (3) 44- 48 I5 mJy S20 The catalogued 20 GHz flux density (4) 49- 52 I4 mJy e_S20 ?=- rms uncertainty on S20 54- 57 I4 mJy S8.4 ?=- Catalogued 8.4 GHz flux density (5) 58- 61 I4 mJy e_S8.4 ?=- rms uncertainty on S8.4 63- 66 I4 mJy S5 ?=- Catalogued 5 GHz flux density (5) 68- 70 I3 mJy e_S5 ?=- rms uncertainty on S5 72- 78 F7.1 mJy S1.4 ?=- For sources north of declination -40°, the total 1.4GHz flux density (6) 79- 86 F8.1 mJy S843 ?=- For sources south of declination -30°, the total 843MHz flux density (7) 89-103 A15 ---- 6dFGS 6dFGS name (gHHMMSSs+DDMMSS) 104 A1 --- l_Offset Limit flag on Offset 105-108 F4.1 arcsec Offset ?=- Offset between the AT20G and 6dFGS position 111-115 F5.2 mag Kmag 2MASS total infrared K-band magnitude Ktot (8) 118-123 F6.4 --- z Optical redshift, as listed in the 6dFGS catalogue (Jones et al. 2009, Cat. VII/259) 126 A1 --- q_z [234J-] 6dFGS redshift quality (9) 129-131 A3 --- Class Spectral classification for galaxies with a good-quality 6dFGS spectrum (10) 134-157 A24 --- Notes Notes
Note (1): Note as follows: a = 6dFGS galaxies identified with AT20G point sources b = 6dFGS galaxies identified with extended or multiple AT20G sources Note (2): For galaxies which are identified with two or more AT20G sources, we list a commonly-used source name instead. Note (3): The 20GHz radio position (J2000) as catalogued by Murphy et al. (2010, Cat. J/MNRAS/402/2403). Note (4): From (Murphy et al. 2010, Cat. J/MNRAS/402/2403). For sources with multiple AT20G components, we list the sum of the component flux densities. Note (5): From (Murphy et al. 2010, Cat. J/MNRAS/402/2403). Note (6): measured from the NVSS catalogue (Condon et al. 1998, Cat. VIII/65). For sources with more than one NVSS component the listed flux is the sum of the components, as described by Mauch & Sadler (2007, Cat. J/MNRAS/375/931). Note (7): measured from the SUMSS catalogue (Mauch et al. 2003, Cat. VIII/70). For sources with more than one SUMSS component the listed flux is the sum of the components. Note (8): from the 2MASS extended source catalogue (Jarrett et al., 2000AJ....120..298J), as listed in the 6dFGS database. Note (9): Quality code (Jones et al., 2004MNRAS.355..747J) as follows: 2 = possible, but doubtful redshift estimate 3 = probable redshift 4 = represents a reliable redshift J = SDSS and ZCAT sources (not a measure of quality) Note (10): Spectral classification code as follows: Aa = absorption-line spectrum, Aae = absorption lines plus weak emission lines, Ae = strong emission lines (see Sadler et al. 1999, Cat. VII/250; 2002, Cat. J/MNRAS/329/227)
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 24-Jul-2017
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