2020/09/24 by M. J. Hardcastle, T. W. Shimwell, C. Tasse +10 · 2 citations
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Brightness #Brightness temperature #Cosmic microwave background #Galaxies: Formation, Evolution, Phenomena #LOFAR #Optics #Physics #Population #Radio Astronomy Observations and Technology #Radio telescope #Sky #Spectral index #Spectral line #astro-ph.CO #astro-ph.GA
paper · pdf · doi:10.1051/0004-6361/202038814
8 pages, 4 figures. This paper is part of the 1st data release of the LoTSS Deep Fields
openalex publication_date 2020/09/24 · arxiv created 2020/11/16 · arxiv updated 2020/11/18 · openalex created_date 2020/11/23 · openalex updated_date 2026/08/05
In recent years, the level of the extragalactic radio background has become a point of considerable interest, with some lines of argument pointing to an entirely new cosmological synchrotron background. The contribution of the known discrete source population to the sky temperature is key to this discussion. Because of the steep spectral index of the excess over the cosmic microwave background, it is best studied at low frequencies where the signal is strongest. The Low-Frequency Array (LOFAR) wide and deep sky surveys give us the best constraints yet on the contribution of discrete extragalactic sources at 144 MHz, and in particular allow us to include contributions from diffuse, low-surface-brightness emission that could not be fully accounted for in previous work. We show that, even with these new data, known sources can still only account for around a quarter of the estimated extragalactic sky temperature at LOFAR frequencies.