J/ApJS/199/27 The ATLBS Extended Source Sample (Saripalli+, 2012)
ATLBS Extended Source Sample: the evolution in radio source morphology with flux density. Saripalli L., Subrahmanyan R., Thorat K., Ekers R.D., Hunstead R.W., Johnston H.M., Sadler E.M. <Astrophys. J. Suppl. Ser., 199, 27 (2012)> =2012ApJS..199...27S
ADC_Keywords: Galaxies, radio ; Interferometry ; Morphology ; Redshifts Keywords: galaxies: active - radio continuum: general - surveys Abstract: Based on the Australia Telescope Low Brightness Survey (ATLBS) we present a sample of extended radio sources and derive morphological properties of faint radio sources. One hundred nineteen radio galaxies form the ATLBS Extended Source Sample (ATLBS-ESS) consisting of all sources exceeding 30" in extent and integrated flux densities exceeding 1mJy. We give structural details along with information on galaxy identifications and source classifications. The ATLBS-ESS, unlike samples with higher flux-density limits, has almost equal fractions of FR-I and FR-II radio galaxies, with a large fraction of the FR-I population exhibiting 3C31-type structures. Significant asymmetry in lobe extents appears to be a common occurrence in the ATLBS-ESS FR-I sources compared with FR-II sources. We present a sample of 22 FR-Is at z>0.5 with good structural information. The detection of several giant radio sources, with size exceeding 0.7Mpc, at z>1 suggests that giant radio sources are not less common at high redshifts. The ESS also includes a sample of 28 restarted radio galaxies. Description: The ATLBS radio images were made at 1388MHz using the Australia Telescope Compact Array (ATCA) by mosaic observing 38 adjacent pointing positions covering about 8.4deg2 of sky area. ATLBS images made with the synthesized beam of 50 arcsec were used as the basic resource for compiling the ATLBS-ESS sample. In the two, 2deg mosaic images, only "islands" of image pixels with peaks exceeding five times the image rms noise were considered. As described in Subrahmanyan et al. (2010, Cat. J/MNRAS/402/2792), the integrated flux density in compact components within these source islands were computed from images made with 4 arcsec FWHM beam using exclusively interferometer baselines to the 6km antenna. The ATLBS survey regions were also observed in optical g, r, and z band with the MOSAICII imager on the CTIO NOAO 4m Blanco telescope. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 261 119 ATLBS (Australia Telescope Low Brightness Survey) Extended Source Sample table4.dat 108 23 *Candidate halo-type radio sources in the ATLBS-ESS
Note on table4.dat: Apart from the sample of 119 sources given in Table 1, we compile ATLBS-ESS sources that are largely devoid of compact components at 4" resolution but are found to have significant flux on extended scales (more than 50% of the flux at 4"). These ∼1mJy radio sources are likely candidate halo-type radio sources that may be associated with individual galaxies, groups, and clusters. These sources appear as a collection of individual resolved sources, some with a dominant source among them. None has a recognizable radio galaxy structure whether of FR-I and FR-II type.
See also: VIII/81 : Sydney University Molonglo Sky Survey (SUMSS V2.1) (Mauch+ 2008) VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998) J/MNRAS/415/1013 : FR II radio galaxies in SDSS (Koziel-Wierzbowska+, 2011) J/MNRAS/402/2792 : 1388MHz ATLBS Low-Brightness Survey (Subrahmanyan+, 2010) J/ApJS/179/306 : Radio galaxy morphologies (Russell+, 2008) J/MNRAS/381/211 : Radio galaxies in the 2SLAQ LRG Survey (Sadler+, 2007) J/ApJS/103/331 : mJy radio sources at 1.4 GHz (Lu+ 1996) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 12 A12 --- ATLBS Source name (JHHMM.m+DDMM) 13- 15 A3 --- f_ATLBS [*,gf ] Flag on ATLBS (1) 17- 18 I2 h RAh Hour of Right Ascension (J2000) 20- 21 I2 min RAm Minute of Right Ascension (J2000) 23- 27 F5.2 s RAs Second of Right Ascension (J2000) 29 A1 --- DE- [-] Sign of the Declination (J2000) 30- 31 I2 deg DEd Degree of Declination (J2000) 33- 34 I2 arcmin DEm Arcminute of Declination (J2000) 36- 40 F5.2 arcsec DEs Arcsecond of Declination (J2000) 42- 45 I4 arcsec LAS [30/1020] Angular size within 3σ contours 47- 50 I4 kpc Size ? Linear size (from table 2) 52- 56 A5 --- Morph Morphology (2) 58- 60 I3 --- Fig [1/119] Figure number 62- 67 F6.2 mJy St Total flux density at 1.4GHz 69- 73 F5.3 --- Sc/St ? Ratio of total and fractional core flux density 75- 86 A12 --- Type Source classification (3) 88- 92 F5.3 --- z ? Redshift 93 A1 --- f_z [r] Redshift estimated from red magnitude (4) 95- 99 F5.2 mag rmag ? r-band magnitude 101-261 A161 --- Comm Additional comments
Note (1): Flag as follows: * = Source selected from region that lies outside the effective primary beam attenuation of 0.5. g = Candidate giant radio galaxy f = Candidate giant radio galaxy with identifications that are too faint to determine reliable r magnitudes. Given their faint magnitudes they are expected to lie at relatively high z. Note (2): Morphology as follows: FR-I = FR-I type radio galaxy (FR-I morphology invariably manifest a pair of bright jets or two-sided extensions to the core and lack well-defined lobes; the cores are the brightest components). FR-II = FR-II type radio galaxy (FR-II sources are usually observed to have a pair of distinct edge-brightened lobes with possibly embedded hot spots/warm spots). WAT = wide angle tail structure; HT = head-tail type structure. See section 3 for further details. Note (3): Classification abbreviation as follows: RS = restarted source; HzFR-I = z>0.5 FR-I; GRG = giant radio galaxy. Note (4): r = Redshifts values estimated using the r-band magnitude-redshift relation.
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 12 A12 --- ATLBS Source name (JHHMM.m+DDMM) 14- 15 I2 h RAh Hour of right ascension (J2000) (1) 17- 18 I2 min RAm Minute of right ascension (J2000) 20- 24 F5.2 s RAs Second of right ascension (J2000) 26 A1 --- DE- Sign of declination (J2000) (1) 27- 28 I2 deg DEd Degree of declination (J2000) (1) 30- 31 I2 arcmin DEm Arcminute of declination (J2000) 33- 36 F4.1 arcsec DEs Arcsecond of declination (J2000) 38- 41 F4.2 --- Fres [1.5/4]? Ratio (low/high resolution) of the flux densities in the 50" and 4" images 43-108 A66 --- Comm Comments
Note (1): The centroid positions from the original 50" images.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 12-Jun-2012
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