Parameter constraints from BINGO simulations with systematic effects, combined with Planck 2018 data. The blue contour shows the posterior from Planck 2018 data alone. The green contour represents a joint constraint from Planck 2018 and a BINGO simulation containing only the cosmological 21-cm signal. The red contour uses the same 21-cm realization but with white noise added. The black dashed contour further includes the process of foreground removal. Dotted black lines mark the fiducial parameter values.