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Spurious fragmentation in filaments
Evolution of neutral/ionised regions during EoR by local cosmic web signature
We identified the cosmic web signature (cluster, filament, wall, void) of points at z=6 and used it to study the neutral/ionised regions between 6<z<17.
Notice how the regions disappear quickly after they split off from the percolating cluster. This explains the Betti-2 persistence diagram.
As expected, the last neutral regions largely trace the underdense regions of the cosmos, shown here as green voids. However, inside these neutral regions there do exist some clusters, filaments, and walls that are obscured from the current viewpoint. To make these visible, we adjust the draw order so that clusters are on top of filaments/walls, which are drawn on top of voids.
Here is another view that shows the locations of the clusters (regardless of their ionisation state).
Here is a snapshot from just before a number of regions split apart. Notice how two large neutral regions containing a fair number of filaments and walls (purple, most are in the interior) are connected by a neutral tunnel that passes through cosmic voids. So the neutral tunnels are not necessarily the cosmic filaments.
Below, the same situation but coloured according to density.
We can also look at the growth of the ionised regions.
Tip: in many browsers you can change the playback speed by right-clicking on the video.