Completeness fraction of mock sources. The grid shows several combinations of the injected peak signal-to-noise ratio (S/N) and line width. The heat map represents how successfully the algorithm, SoFiA2 (Westmeier et al. 2021), detects mock sources injected into data cubes, with the recovery fraction indicated by the colour. For sources with S/N ≳ 4 and line width ≳300 km s⁻¹ we reach a completeness above ∼75%.