Contribution to the Diffuse Radio Background from Extragalactic Radio Sources

TL;DR

This paper estimates the contribution of known radio sources to the Cosmic Radio Background across multiple frequencies, finding that an additional faint source population is needed to explain measurements, especially at 1.4 GHz.

Contribution

It provides a comprehensive analysis of radio source contributions to the CRB using Monte Carlo methods, highlighting the necessity of a faint, undetected source population.

Findings

Calculated contributions match measurements at several frequencies.

Additional faint sources are required below 10 μJy at 1.4 GHz.

Systematic errors were carefully considered in the estimates.

Abstract

We examine the brightness of the Cosmic Radio Background (CRB) by comparing the contribution from individual source counts to absolute measurements. We use a compilation of radio counts to estimate the contribution of detected sources to the CRB in several different frequency bands.We apply a Monte Carlo Markov Chain technique to estimate the brightness values and uncertainties, paying attention to various sources of systematic error. We compare our results to absolute measurements from the ARCADE 2 experiment. At v = 150 MHz, 325 MHz, 408 MHz, 610 MHz, 1.4 GHz, 4.8 GHz, and 8.4 GHz our calculated contributions to the background sky temperature are 18, 2.8, 1.6, 0.71, 0.11, 0.0032, 0.0059 K, respectively. If the ARCADE 2 measurements are correct and come from sources, then there must be an additional population of radio galaxies, fainter than where current data are probing. More specifically, the Euclidean-normalized counts at 1.4 GHz have to have an additional bump below about 10 {\mu}Jy.