D. Guidetti
The eMERGE Survey - I: Very Large Array 5.5 GHz observations of the GOODS-North Field
Guidetti, D.; Bondi, M.; Prandoni, I.; Muxlow, T.W.B.; Beswick, R.; Wrigley, N.; Smail, I.; McHardy, I.; Thomson, A.P.; Radcliffe, J.; Argo, M.K.
Authors
M. Bondi
I. Prandoni
T.W.B. Muxlow
R. Beswick
N. Wrigley
Professor Ian Smail ian.smail@durham.ac.uk
Emeritus Professor
I. McHardy
A.P. Thomson
J. Radcliffe
M.K. Argo
Abstract
We present new observations of the GOODS-N field obtained at 5.5 GHz with the Karl G. Jansky Very Large Array. The central region of the field was imaged to a median rms of 3 μJy beam−1 with a resolution of 0.5 arcsec. From a 14-arcmin diameter region, we extracted a sample of 94 radio sources with signal-to-noise ratio greater than 5. Near-IR identifications are available for about ∼88 per cent of the radio sources. We used different multiband diagnostics to separate active galactic nuclei (AGNs), both radiatively efficient and inefficient, from star-forming galaxies. From our analysis, we find that about 80 per cent of our radio-selected sample is AGN dominated, with the fraction rising to 92 per cent when considering only the radio sources with redshift >1.5. This large fraction of AGN-dominated radio sources at very low flux densities (the median flux density at 5.5 GHz is 42 μJy), where star-forming galaxies are expected to dominate, is somewhat surprising and at odds with other results. Our interpretation is that both the frequency and angular resolution of our radio observations strongly select against radio sources whose brightness distribution is diffuse on a scale of several kpc. Indeed, we find that the median angular sizes of the AGN-dominated sources is around 0.2–0.3 arcsec against 0.8 arcsec for star-forming galaxies. This highlights the key role that high frequency radio observations can play in pinpointing AGN-driven radio emission at μJy levels. This work is part of the eMERGE legacy project.
Citation
Guidetti, D., Bondi, M., Prandoni, I., Muxlow, T., Beswick, R., Wrigley, N., …Argo, M. (2017). The eMERGE Survey - I: Very Large Array 5.5 GHz observations of the GOODS-North Field. Monthly Notices of the Royal Astronomical Society, 471(1), 210-226. https://doi.org/10.1093/mnras/stx1162
Journal Article Type | Article |
---|---|
Acceptance Date | May 10, 2017 |
Online Publication Date | Jul 15, 2017 |
Publication Date | Jul 15, 2017 |
Deposit Date | Aug 21, 2017 |
Publicly Available Date | Mar 29, 2024 |
Journal | Monthly Notices of the Royal Astronomical Society |
Print ISSN | 0035-8711 |
Electronic ISSN | 1365-2966 |
Publisher | Royal Astronomical Society |
Peer Reviewed | Peer Reviewed |
Volume | 471 |
Issue | 1 |
Pages | 210-226 |
DOI | https://doi.org/10.1093/mnras/stx1162 |
Publisher URL | http://ukads.nottingham.ac.uk/abs/2017MNRAS.471..210G |
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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2017. The Authors.
Published by Oxford University Press on behalf of the Royal Astronomical Society.
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