Extended Data Fig. 3: Foreground modelling.
From: The REACH radiometer for detecting the 21-cm hydrogen signal from redshift z ≈ 7.5–28
Top: Plot showing the subdivision of the sky in galactic coordinates into a number of regions N=6 of similar spectral index. Bottom: Plot comparing the residuals from fitting simulated 21-cm data. The plots shows the results of fitting data with a 5th order log-polynomial model (left), fitting data corrected by (A1) with a 5th order log-polynomial model (centre) and fitting the data with the REACH pipeline, using N=9 (right). The residuals after subtraction of the foreground models are shown in red. The signal model and true signal inserted into the simulated data, are shown in blue and green respectively, where visible. These results are simulated using a conical log-spiral antenna and a hexagonal dipole antenna.
