标题： 150 MHz–8.4 GHz的宇宙射电背景及其划分为活动星系核和星形成 galaxies 的流量 显示英文标题

标题： The cosmic radio background from 150 MHz--8.4 GHz, and its division into AGN and star-forming galaxy flux

摘要： 我们基于近乎完整的射电源计数数据集，提出了对星系际背景光（EBL）在射电波段的重新测量。 我们给出了150 MHz、325 MHz、610 MHz、1.4 GHz、3 GHz、5 GHz和8.4 GHz频段的射电-EBL。 在所有情况下，每十年流量的射电-EBL贡献呈现出两个峰分布，很好地与活动星系核（AGN）和恒星形成星系（SFG）群体匹配，并且每个群体贡献的能量大致相等。 只有在3 GHz时，源计数对EBL的贡献完全收敛，因此我们在剩余频段报告了经验性的下限值。 采用SHARK半解析模型对恒星形成星系（SFG）群体形式的预测，我们可以拟合较暗弱的源计数，从而分别测量恒星形成星系和活动星系核群体对射电-EBL的总贡献。 这构成了一种依赖于模型的经验性约束测量方法来估算恒星形成星系的贡献，但对活动星系核的贡献则是完全经验性的测量。 利用{\sc ProSpect}光谱能量分布代码，我们可以根据宇宙恒星形成历史以及采用Chabrier初始质量函数，对从紫外到光学、红外、毫米波及射电波段的恒星形成星系EBL进行建模。 然而，在射电-EBL的源计数估计与ARCADE-2实验报告的直接测量之间仍存在显著差异（$5\times$）。 我们可以排除显著缺失的离散射电源群体，并建议ARCADE-2射电-EBL值较高的原因可能需要在前景减除过程中寻找，或者作为射电天空中的未知弥散成分。 显示英文摘要

摘要： We present a revised measurement of the extra-galactic background light (EBL) at radio frequencies based on a near complete compendium of radio source counts. We present the radio-EBL at 150 MHz, 325 MHz, 610 MHz, 1.4 GHz, 3 GHz, 5 GHz, and 8.4 GHz. In all cases the contribution to the radio-EBL, per decade of flux, exhibits a two-humped distribution well matched to the AGN and star-forming galaxy (SFG) populations, and with each population contributing roughly equal energy. Only at 3 GHz are the source count contributions to the EBL fully convergent, and hence we report empirical lower limits to the radio-EBL in the remaining bands. Adopting predictions from the SHARK semi-analytic model for the form of the SFG population, we can fit the fainter source counts providing measurements of the total contribution to the radio-EBL for the SFG and the AGN populations separately. This constitutes an empirically constrained model-dependent measurement for the SFG contribution, but a fully empirical measurement of the AGN contribution. Using the {\sc ProSpect} spectral energy distribution code we can model the UV-optical-infrared-mm-radio SFG EBL at all frequencies from the cosmic star-formation history and the adoption of a Chabrier initial mass function. However, significant discrepancy remains ($5\times$) between our source-count estimates of the radio-EBL and the direct measurements reported from the ARCADE-2 experiment. We can rule out a significant missing discrete source radio population and suggest that the cause of the high ARCADE-2 radio-EBL values may need to be sought either in the foreground subtraction or as a yet unknown diffuse component in the radio sky.