J/A+A/402/171 Faint CSS radio sources at 74 MHz (Tschager+, 2003)
The determination of the spectral turnover in faint
compact steep-spectrum radio sources using the VLA at 74 MHz.
Tschager W., Schilizzi R.T., Roettgering H.J.A., Snellen I.A.G.,
Miley G.K., Perley R.A.
<Astron. Astrophys. 402, 171 (2003)>
=2003A&A...402..171T 2003A&A...402..171T
ADC_Keywords: Radio sources
Keywords: radio continuum: galaxies - galaxies: active - galaxies: evolution
Abstract:
We carried out VLA observations in A configuration at 74-MHz of a new
sample of faint Compact Steep-Spectrum (CSS) radio sources as part of
a comprehensive project to study the nature and evolution of
peaked-spectrum radio sources. In conjunction with higher frequency
spectral information this has enabled us to determine the peak
frequency and peak flux density of the spectral turnover for 35 faint
CSS radio sources. Spectra are presented. An analysis is given of the
quality of the images and their suitability for integrated intensity
measurements of the CSS radio sources.
Description:
Using the WENSS (VIII/62), NVSS (VIII/65) and FIRST (VIII/71)
radio surveys, we have constructed a new sample of faint CSS sources
to fill in an unexplored segment of the peak-flux-density -
peak-frequency parameter space. Unresolved radio sources located in
the area 08h<RA<17h and 30°<DE<43° with a flux density >250mJy
were selected from WENSS at 325MHz, and their positions were
correlated with the NVSS catalogue at 1.4GHz. Sources with an
optically thin radio spectrum of α<0.5 (S∝ν^α)
were subsequently selected. We then correlated this sample of
steep-spectrum radio sources with the 1.4GHz FIRST catalogue to
select only those sources with a deconvolved size of <2". This
selection on spectral index and angular extension is the same as used
by Fanti et al. (1990A&A...231..333F 1990A&A...231..333F) for selecting the reference
sample of bright CSS sources mainly from the 3CR catalogue. From a
total of 402 objects found, we selected a working sample composed of
99 sources, mostly located in the region of the sky limited by
08h<RA<17h and 30°<DE<43°.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 36 35 Peak flux densities and peak frequencies for
35 CSS sources.
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See also:
VIII/62 : The Westerbork Northern Sky Survey (Leiden, 1998)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
VIII/71 : The FIRST Survey Catalog, Version 03Apr11 (Becker+ 2003)
J/A+A/369/380 : CSS/GPS radio sources VLA observations (Fanti+, 2001)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- [TSR2003] Source name (JHHMM+DDMM)
12- 15 I4 mJy S74MHz ? Flux density at 74MHz
17- 20 I4 mJy SPeak Peak flux-density (1)
22- 24 I3 MHz nuPeak Peak frequency (1)
26- 30 F5.2 --- alphaThick Spectral index below the turnover (fixed) (1)
32- 36 F5.2 --- alphaThin Spectral index above the turnover (1)
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Note (1): The fitted quantities and integrated intensities have
associated uncertainties of 20%.
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History:
From electronic version of the journal
(End) James Marcout, Patricia Bauer [CDS] 26-May-2003