Marginal posterior distributions of the Gaussian mixing fraction ξ. The left panel shows the probability density function (PDF); the right panel its cumulative density function (CDF). The fraction ξ refers to the mixing fraction of the Gaussian component, which is enforced at alignment in the Aligned + Isotropic model (μ_t = 1) or moves freely in all others (−1 ≤ μ_t ≤ 1), whereas 1 − ξ refers to the isotropic fraction. For the Gaussian + Isotropic + Cut and Aligned + Isotropic + Cut models, the fractions ξ and 1 − ξ describe the mixing in the low-mass population (﹩{m}_{1}\,\lesssim \,\tilde{m}﹩).