The mass function of luminous satellite problem. The cumulative distribution function for the mass within the central 300 pc, M_0.3   kpc, of the MW satellites (solid line) and the cumulative distribution function for M_0.3   kpc of a sample of 10⁶ CDM-halos picked from the parent distribution of luminous sub-halos (Eq. (8), dashed line). The null hypothesis is that the MW satellite M_0.3   kpc masses are drawn from this parent distribution. The maximum distance between the two curves is 0.333 so that the null hypothesis can be discarded with 98.9 per cent confidence.