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Paper: The Star-formation History of the Universe as Revealed from Deep Radio Observations of the 13H XMM-Newton/Chandra Deep Field
Volume: 380, At the Edge of the Universe: Latest Results from the Deepest Astronomical Surveys
Page: 287
Authors: Seymour, N.; Dwelly, T.; Moss, D.; McHardy, I.; Page, M.; Loaring, N.; Reieke, G.
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 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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