A novel approach for characterising broadband radio spectral energy distributions

Abstract

We present a new broadband radio frequency catalogue across 0.12 GHz $\le \nu \le$ 20 GHz created by combining data from the Murchison Widefield Array Commissioning Survey, the Australia Telescope 20 Gigahertz survey, and the literature. Our catalogue consists of 1285 sources limited by $S_{20\mathrm{GHz}}>$ 40 mJy at $5\sigma$, and contains flux density measurements (or estimates) and uncertainties at 0.074, 0.080, 0.119, 0.150, 0.180, 0.408, 0.843, 1.4, 4.8, 8.6, and 20 GHz. We fit a second-order polynomial in log-log space to the spectral energy distributions of all these sources in order to characterise their broadband emission. For the 994 sources which are well-described by a linear or quadratic model we present a new diagnostic plot arranging sources by the linear and curvature terms. We demonstrate the advantages of such a plot over the traditional radio colour-colour diagram. We also present astrophysical descriptions of the sources found in each segment of this new parameter space and discuss the utility of these plots in the upcoming era of large area, deep, broadband radio surveys.

arXiv comment15 pages, 10 figures, 7 tables, with ancillary data. Accepted for publication in MNRAS

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• GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey I: A low-frequency extragalactic catalogue
• The VLA Low-frequency Sky Survey
• The Australia Telescope 20 GHz Survey: The Source Catalogue
• GLEAM: The GaLactic and Extragalactic All-sky MWA survey
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• The AT20G high angular resolution catalogue
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Cited by in corpus (2)

• Science with the Murchison Widefield Array: Phase I Results and Phase II Opportunities
• The ATLAS 9.0 GHz Survey of the Extended Chandra Deep Field South: The Faint 9.0 GHz Radio Population