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 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:
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FileName Lrecl Records Explanations
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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
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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.
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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
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Bytes Format Units Label Explanations
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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
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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.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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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
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Note (1): The centroid positions from the original 50" images.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 12-Jun-2012