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The VLA-COSMOS Survey - V.324 MHz continuum observations

Abstract : We present 90 cm Very Large Array imaging of the COSMOS field, comprising a circular area of 3.14 square degrees at 8.0arcsec x 6.0arcsec angular resolution with an average rms of 0.5 mJy beam(-1). The extracted catalogue contains 182 sources (down to 5.5 sigma), 30 of which are multicomponent sources. Using Monte Carlo artificial source simulations, we derive the completeness of the catalogue, and we show that our 90 cm source counts agree very well with those from previous studies. Using X-ray, NUV-NIR and radio COSMOS data to investigate the population mix of our 90 cm radio sample, we find that our sample is dominated by active galactic nuclei. The average 90-20 cm spectral index (S-nu proportional to nu(alpha), where S-nu is the flux density at frequency nu and alpha the spectral index) of our 90 cm selected sources is -0.70, with an interquartile range from -0.90 to -0.53. Only a few ultra-steep-spectrum sources are present in our sample, consistent with results in the literature for similar fields. Our data do not show clear steepening of the spectral index with redshift. Nevertheless, our sample suggests that sources with spectral indices steeper than -1 all lie at z greater than or similar to 1, in agreement with the idea that ultra-steep-spectrum radio sources may trace intermediate-redshift galaxies (z greater than or similar to 1).
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https://hal.archives-ouvertes.fr/hal-01441996
Contributor : Catherine Beaussier Connect in order to contact the contributor
Submitted on : Friday, January 20, 2017 - 1:26:32 PM
Last modification on : Tuesday, October 19, 2021 - 10:59:20 PM

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Olivier Ilbert, Alexander Karim, Henry Mccracken, Nick Z. Scoville, Vernesa Smolcic, et al.. The VLA-COSMOS Survey - V.324 MHz continuum observations. Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P - Oxford Open Option A, 2014, 443 (3), pp.2590--2598. ⟨10.1093/mnras/stu1331⟩. ⟨hal-01441996⟩

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