The fraction of baryons that managed to collapse by the time the outermost shell of the dark matter halo had collapsed. The curves were obtained with the same hydrodynamics code as in Fig. 1. Six different curves are shown for the six different peak heights, 0.5–3 σ, as in Fig. 1. These curves yield an "equivalent cosmological Jeans mass" of 10³ M_☉ (see § 2.1).