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The Star-formation History of the Universe as Revealed from Deep Radio Observations of the 13H XMM-Newton/Chandra Deep Field

N. Seymour·T. Dwelly·D. Moss·I. McHardy·M. Page·N. Loaring·G. Reieke
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Abstract

Discerning the exact nature of the faint (sub-mJy) radio population has been historically difficult due to the low luminosity of these sources at most wavelengths. Using deep observations from Chandra/XMM-Newton/Spitzer and ground based follow up we are able to disentangle the AGN and star-forming populations for the first time in a deep multi-frequency GMRT/VLA/MERLIN Survey. The many diagnostics include radio luminosity, morphology, radio to mid-IR flux density ratios, radio to optical flux density ratios and radio spectral indices. Further diagnostics, e.g. optical spectra X-ray spectra/hardness ratios, IR colours indicate the presence of the AGN {\em independent} of whether the radio emission is powered by AGN or star-formation. We are able to examine the star-formation history of the universe up to z=2.5 in a unique way based on an unbiased star-formation rate indicator, radio luminosity. This work provides an alternative perspective on the distribution of star-formation by mass, ``downsizing'' and allows us to examine the prevalence of AGN in star-bursts.

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N. Seymour, T. Dwelly, D. Moss, I. McHardy, M. Page, N. Loaring, G. Reieke. 2006-12-05. The Star-formation History of the Universe as Revealed from Deep Radio Observations of the 13H XMM-Newton/Chandra Deep Field. https://arxiv.org/abs/astro-ph/0612134

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