Extended Data Fig. 4: Halo mass vs. redshift.

The masses in (a) are from z = 35 (80 Myr after the Big Bang), when it crosses the threshold for normal Pop III star formation, to z = 25.7 (126 Myr after the Big Bang), when it begins to dynamically collapse. The subsequent growth of the halo from z = 15 to z = 6 is shown in (b).