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

Abstract

We present 90 cm VLA imaging of the COSMOS field, comprising a circular area of 3.14 square degrees at 8.0"x6.0" angular resolution with an average rms of 0.5 mJy/beam. The extracted catalog contains 182 sources (down to 5.5sigma), 30 of which are multi-component sources. Using Monte Carlo artificial source simulations we derive the completeness of the catalog, 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 (AGN). The average 90-20 cm spectral index (S_nu~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 of -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>1, in agreement with the idea that ultra-steep-spectrum radio sources may trace intermediate-redshift galaxies (z>1).

10 pages, 12 figures, accepted for publication in MNRAS

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Cited by in corpus (10)

• Physical properties of z>4 submillimeter galaxies in the COSMOS field
• Near Infrared Variability of obscured and unobscured X-ray selected AGN in the COSMOS field
• High-redshift quasars at $z\ge 3$ -- I. Radio spectra
• New insights from deep VLA data on the potentially recoiling black hole CID-42 in the COSMOS field
• Radio spectra of bright compact sources at z>4.5
• The composite nature of Dust-Obscured Galaxies (DOGs) at z~2-3 in the COSMOS field: I. A Far-Infrared View
• A closer look at the deep radio sky: Multi-component radio sources at 3-GHz VLA-COSMOS
• Deep observations of the Super-CLASS super-cluster at 325 MHz with the GMRT: the low-frequency source catalogue
• The Radio Spectral Energy Distribution and Star Formation Calibration in MIGHTEE-COSMOS Highly Star-Forming Galaxies at 1.5 < z < 3.5
• Radio properties of high-redshift galaxies at $z\ge 1$