The First Galaxies and the Likely Discovery of Their Fossils in the Local Group
Figure 1
3D rendering of cosmological H II regions (fully ionized gas is red and partially ionized gas is blue) around the first galaxies in a box of 1.5 Mpc. The four boxes show a time sequence at redshifts for the simulation S2 from Ricotti et al. [41]. The rendering shows several tens of small size H II regions around the first galaxies (there are a few hundreds of galaxies in this volume). A movie of the same simulation shows that the H II regions are short lived: they form and expand to a size comparable to the large-scale filamentary structure of the IGM and recombine, promoting the formation of molecular hydrogen inside the relic H II regions.
