Reliability of our sAM estimator. Left: bottom panel: total SFR-weighted sAM, (in km s⁻¹ kpc), as a function of the true angular momentum (SFR-weighted) for the 790 mock galaxies. Top panel: relative error ( as a function of the effective S/N (see text) along with the histogram of . The points are colored according to the stellar mass in both panels. The red circles represent the median whose errorbar represent 1σ. Right: relative error ( for each mass bin of 1 dex centered on log M_⋆ = 8.5, 9.5, 10.5, from top to bottom. The histograms are weighted by the errors. Left (right) panels: distributions of , in three mass bins, resulting from the 3D method (the Eq. (3) approximation), respectively. The red solid line represents the continuous density estimation of the distributions using a Gaussian kernel with bandwidth of ∼0.2. This shows that, for massive galaxies (M_⋆ > 10¹⁰ M_⊙), the Eq. (3) approximation is less biased, while for galaxies with M_⋆ < 10¹⁰ M_⊙, the 3D method is less biased.