J/MNRAS/493/2841 Faint radio source population at 15.7GHz - IV (Whittam+, 2020)
The faint radio source population at 15.7 GHz
IV. The dominance of core emission in faint radio galaxies.
Whittam I.H., Green D.A., Jarvis M.J., Riley J.M.
<Mon. Not. R. Astron. Soc., 493, 2841-2853 (2020)>
=2020MNRAS.493.2841W 2020MNRAS.493.2841W (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, radio ; Radio continuum ; Active gal. nuclei ;
Photometry, ugriz ; Photometry, infrared ; Redshifts
Keywords: catalogues - surveys - galaxies: active - radio continuum: galaxies
Abstract:
We present 15-GHz Karl G. Jansky Very Large Array observations of a
complete sample of radio galaxies selected at 15.7GHz from the Tenth
Cambridge (10C) survey. 67 out of the 95 sources (71 per cent) are
unresolved in the new observations and lower frequency radio
observations, placing an upper limit on their angular size of
∼2arcsec. Thus, compact radio galaxies, or radio galaxies with very
faint jets, are the dominant population in the 10C survey. This
provides support for the suggestion in our previous work that
low-luminosity (L<1025WHz-1) radio galaxies are core dominated,
although higher resolution observations are required to confirm this
directly. The 10C sample of compact, high-frequency selected radio
galaxies is a mixture of high-excitation and low-excitation radio
galaxies and displays a range of radio spectral shapes, demonstrating
that they are a mixed population of objects.
Description:
This work is based on a sample selected from the 10C survey at
15.7GHz. The 10C survey was observed with the Arcminute Microkelvin
Imager (AMI; Zwart et al. 2008MNRAS.391.1545Z 2008MNRAS.391.1545Z) Large Array and covers
27deg2 complete to 1mJy in 10 different fields, and a further
12deg2 complete to 0.5mJy contained within these fields. Here, we
use a complete sample of 96 sources selected from a region of the 10C
survey in the Lockman Hole with particularly good low-frequency data
available.
There is a wealth of multiwavelength data available in the Lockman
Hole, most of which is contained in the 'SERVS Data Fusion' catalogue
(Vaccari 2015fers.confE..27V), a multiwavelength catalogue selected in
the mid-infrared. In the Lockman Hole, this catalogue contains data
from the Spitzer Wide-Area Infrared Extragalactic Survey (SWIRE; see
Lonsdale et al. 2003PASP..115..897L 2003PASP..115..897L), the Spitzer Extragalactic
Representative Volume Survey (SERVS; see Mauduit et al.
2012PASP..124..714M 2012PASP..124..714M), and the United Kingdom Infrared Telescope
Infrared Deep Sky Survey (see Lawrence et al. 2007MNRAS.379.1599L 2007MNRAS.379.1599L,
Cat. II/314).
The new data were taken with the Karl G. Jansky VLA in C configuration
in the Ku band. Pointed observations were made of the 96 sources in
the sample. The 75 sources with S10C>0.75mJy (S10C is the 15-GHz
peak flux density from the 10C catalogue) were observed for 50s on
source. The fainter sources with S10C<0.75mJy (21 sources) were
observed for a time scaled according to the 10C peak flux density of
each source. The observations were split into two scheduling blocks
(SBs) containing 42 and 54 sources, and these were observed on 2017
May 31 and 2017 June 11, respectively.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 99 95 Properties of the sources in this sample based
on the new VLA observations
tableb1.dat 180 95 Host galaxy catalogue
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See also:
J/MNRAS/429/2080 : Lockman Hole 10C sources radio spectral indices
(Whittam+ 2013)
J/MNRAS/453/4244 : Faint radio source population at 15.7GHz (Whittam+, 2015)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- Name Source name (10C JHHMMSS+DDMMSS)
21- 22 I2 h RAh Right ascension (J2000)
24- 25 I2 min RAm Right ascension (J2000)
27- 32 F6.3 s RAs Right ascension (J2000)
34 A1 --- DE- Declination sign (J2000)
35- 36 I2 deg DEd Declination (J2000)
38- 39 I2 arcmin DEm Declination (J2000)
41- 45 F5.2 arcsec DEs Declination (J2000)
47- 53 F7.4 mJy Speak Peak flux density in VLA image
55- 59 F5.3 mJy e_Speak Error on Speak
61- 66 F6.3 mJy Sint Integrated flux density in VLA image
68- 72 F5.3 mJy e_Sint Error on Sint
74 I1 --- Ncomp Number of components source is resolved into
76- 78 I3 uJy/beam rms Local rms noise in VLA image (measured in a
100x100 pixel box away from the source)
80- 84 F5.3 mJy Score ? Flux density of core component
86- 90 F5.1 arcsec theta Angular size of source measured at 15 GHz
92 A1 --- f_theta [0/1] Flag on theta (1)
94- 99 A6 --- FRclass Morphological classification (2)
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Note (1): Flag as follows:
0 = True value
1 = Upper limit
Note (2): Classification as follows:
FR0/I = Compact radio galaxy or Fanaroff and Riley type I source (3/95)
FR0c = Candidate compact steep spectrum (CSS) source (13/95)
FR0g = Candidate GHz-peaked spectrum (GPS) source (8/95)
FR0u = Uncertain compact source (46/95)
FRI = Fanaroff and Riley type I source (6/95)
FRI/II = FRI or FRII source (1/95)
FRII = Fanaroff and Riley type II source (17/95)
SFG = Star-forming galaxy (1/95)
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Byte-by-byte Description of file: tableb1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- Name Source name (10C JHHMMSS+DDMMSS)
21- 25 F5.2 mag gmag ? g-band magnitude
27- 31 F5.3 mag e_gmag ? Error on gmag
33- 37 F5.2 mag imag ? i-band magnitude
39- 43 F5.3 mag e_imag ? Error on imag
45- 49 F5.2 mag rmag ? r-band magnitude
51- 55 F5.3 mag e_rmag ? Error on rmag
57- 60 F4.1 mag zmag ? z-band magnitude
62- 66 F5.3 mag e_zmag ? Error on zmag
68- 72 F5.2 mag Jmag ? J-band magnitude
74- 77 F4.2 mag e_Jmag ? Error on Jmag
79- 83 F5.2 mag Kmag ? K-band magnitude
85- 88 F4.2 mag e_Kmag ? Error on Kmag
90- 96 F7.2 uJy SERVS1 ? SERVS 3.6um magnitude
98-101 F4.2 uJy e_SERVS1 ? Error on SERVS1
103-108 F6.2 uJy SERVS2 ? SERVS 4.5um magnitude
110-113 F4.2 uJy e_SERVS2 ? Error on SERVS2
115-121 F7.2 uJy SWIRE1 ? SWIRE 3.6um magnitude
123-126 F4.2 uJy e_SWIRE1 ? Error on SWIRE1
128-133 F6.2 uJy SWIRE2 ? SWIRE 4.5um magnitude
135-138 F4.2 uJy e_SWIRE2 ? Error on SWIRE2
140-145 F6.2 uJy SWIRE3 ? SWIRE 5.8um magnitude
147-150 F4.2 uJy e_SWIRE3 ? Error on SWIRE3
152-158 F7.2 uJy SWIRE4 ? SWIRE 8.0um magnitude
160-163 F4.2 uJy e_SWIRE4 ? Error on SWIRE4
165-168 F4.2 --- z ? Final redshift value
170 I1 --- r_z [1/4]? Reference for z (1)
172 A1 --- Optcomp [EP ] Source extension (2)
174 A1 --- Lacy [YN ] Indicates if the source is located
inside the Lacy et al.
(2004ApJS..154..166L 2004ApJS..154..166L) area (3)
176 A1 --- Xray [YN ] Indicates if the source is detected
by an X-ray survey (4)
178 A1 --- SpClass [HL ] Spectral classification (5)
180 A1 --- Class [HL ] Overall HERG (H) or LERG (L)
classification
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Note (1): Flag as follows:
1 = Spectroscopic redshift
2 = Rowan-Robinson et al. (2013MNRAS.428.1958R 2013MNRAS.428.1958R, Cat. II/326)
3 = Fotopoulou et al. (2012ApJS..198....1F 2012ApJS..198....1F, Cat. J/ApJS/198/1)
4 = Photometric redshift obtained using LE PHARE code (Arnouts et al.
1999MNRAS.310..540A 1999MNRAS.310..540A)
Note (2): Extension as follows:
E = Extended source (58/95)
P = Point-like (8/95)
Note (3): Classification as follows:
Y = The source is located inside the Lacy et al. (2004ApJS..154..166L 2004ApJS..154..166L) area
on the mid-infrared colour-colour diagram (23/95)
N = The source is located outside this region (including sources with
limits that must lie outside this region) (38/95)
Note (4): X-ray detection as follows:
Y = The source is detected by an X-ray survey (15/95)
N = The source lies inside X-ray survey area but is not detected (16/95)
Note (5): Spectral class as follows:
H = The source is classified as a high-excitation radio galaxy (HERG) based
on its optical spectrum (7/95)
L = The source is classified as a low-excitation radio galaxy (LERG) based
on its optical spectrum (15/95)
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History:
From electronic version of the journal
References:
Whittam et al., Paper I 2013MNRAS.429.2080W 2013MNRAS.429.2080W, Cat. J/MNRAS/429/2080
Whittam et al., Paper II 2015MNRAS.453.4244W 2015MNRAS.453.4244W, Cat. J/MNRAS/453/4244
Whittam et al., Paper III 2016MNRAS.462.2122W 2016MNRAS.462.2122W
(End) Ana Fiallos [CDS] 19-Apr-2023