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Paper: Disentangling AGN/Starbursts in Deep Radio Surveys - Radio Spectral Properties
Volume: 380, At the Edge of the Universe: Latest Results from the Deepest Astronomical Surveys
Page: 275
Authors: Moss, D.; Seymour, N.; McHardy, I.M.; Dwelly, T.; Page, M.J.; Loaring, N.S.
Abstract: We present the results of a deep 610 MHz survey conducted as part of a study into the radio spectral properties of the faint radio population. We have observed the 1H XMM/Chandra survey area with the GMRT. To a 5σ detection limit of 283 μJy we detect 222 sources within a survey area of diameter 64 arcmin. We compute the 610 MHz source counts and compare them to those at other radio wavelengths. The well know flattening of the Euclidean-normalised 1.4 GHz source counts below ~2 mJy, usually explained by a population of starburst galaxies undergoing luminosity evolution, is seen for the first time at 610 MHz. The 610 MHz source counts can be modelled by the same populations that explain the 1.4 GHz source counts, assuming a spectral index of 0.8 for the starburst galaxies and the steep spectrum AGN population. We find a similar dependence of luminosity evolution on redshift for the starburst galaxies at 610MHz as is found at 1.4 GHz (i.e. Q= 2.3+0.3−0.5). A preliminary reduction of deeper observations gives spectral indices for ~ 60 sources, ~ 20 of which are candidate ultra steep spectrum sources.
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