The progress of cosmic reionization, as hydrogen atoms are ionized by the light emitted by stars and black holes, traced from z=12 to z=6, a period of time just over half a billion years. This visualization is a volume rendering of the remaining neutral hydrogen, shown in gray. Ionization fronts (defined as having HII fractions greater than 50%) highlight neutral 'islands' of gas. These take the form of bubbles which propagate outwards from luminous sources, slowing percolating to eventually encompass the entire simulation. Here, a scenario of quasar-only reionization is tested.

Methods: RAMSES + RADAMESH codes