Impact of extragalactic point sources on the foregrounds and 21-cm observations

Observation of the global 21-cm signal is hindered by the presence of strong foregrounds. Galactic emissions form a significant portion of these foregrounds, which is a reasonably well-understood part of the foregrounds. However, lesser understood is the contribution due to the extragalactic point radio sources. I will present a model of the foregrounds due to extragalactic point radio sources and show that point sources have a smooth and small contribution which is just a few %  of the total observed foregrounds, but still larger by at least an order of magnitude than the  cosmological 21-cm signal. As a consequence, if unaccounted for in the fitted model, we are lead to a poor 21-cm signal recovery. We propose a solution to this; the points sources contribution in the data can be captured by a power law function with a running spectral index.