Hi, Once the Universe has completed reionization (at redshift >~6 ), the intergalactic medium (IGM) is completely ionized (even if some neutral clumps can persist). On the other hand, it seems that galaxies were accreting a lot of gas from the IGM after reionization so that they could form stars. It appears that this gas accretion can follow 2 modes, either (1) "cold gas" from IGM directly feed galaxies, or (2) IGM gas is heated when falling in the potential well of dark matter halos and then cools onto galaxies. My question is the following: this IGM gas which is accreted by galaxies/halos should be ionized after reionization. Then, since the fuel for star formation is neutral gas, how the ionized gas can recombine in each of these 2 regimes of accretion? Regards.