A novel approach for characterising broadband radio spectral energy distributions

TL;DR

This paper introduces a new broadband radio frequency catalogue and a novel diagnostic plot for characterising radio spectral energy distributions, improving analysis of large radio surveys.

Contribution

The paper presents a comprehensive radio source catalogue from 0.12 to 20 GHz and a new diagnostic plot based on polynomial fits to spectral data, enhancing spectral analysis methods.

Findings

Catalogue of 1285 sources with flux measurements across 0.074-20 GHz.

New diagnostic plot effectively classifies sources by spectral curvature.

Demonstrates advantages over traditional radio colour-colour diagrams.

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 $S_{20\,\rm{GHz}} >$ 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.