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GMRT 610-MHz observations of the faint radio source population – and what these tell us about the higher radio-frequency sky

Published version
Peer-reviewed

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Authors

Whittam, IH 
Green, DA 
Jarvis, MJ 
Riley, JM 

Abstract

We present 610-MHz Giant Metrewave Radio Telescope observations of 0.84 deg2 of the AMI001 field (centred on 00$^{h}23^{m}10^{s},+31°53)withanrmsnoiseof18μJybeam^{-1}$ in the centre of the field. A total of 955 sources are detected, and 814 are included in the source count analysis. The source counts from these observations are consistent with previous work. We have used these data to study the spectral index distribution of a sample of sources selected at 15.7 GHz from the recent deep extension to the Tenth Cambridge (10C) survey. The median spectral index, α, (where S ∝ να) between 0.08<S15.7GHz/mJy<0.2 is 0.32 ± 0.14, showing that star-forming galaxies, which have much steeper spectra, are not contributing significantly to this population. This is in contrast to several models, but in agreement with the results from the 10C ultradeep source counts; the high-frequency sky therefore continues to be dominated by radio galaxies down to S15.7GHz = 0.1 mJy.

Description

Keywords

catalogues, surveys, galaxies: active, radio continuum: galaxies

Journal Title

Monthly Notices of the Royal Astronomical Society

Conference Name

Journal ISSN

0035-8711
1365-2966

Volume Title

464

Publisher

Oxford University Press
Sponsorship
Science and Technology Facilities Council (ST/J004774/1)
The GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research. IHW thanks the Science and Technologies Facilities Council for a studentship. IHW and MJJ acknowledge support from the Square Kilometre Array South Africa. IHW thanks the South African Astronomical Observatory, where some of this work was carried out.