Local radiative feedback in the formation of the first protogalaxies

The first galaxies form under the influence of radiative feedback from the first generations of stars. This feedback acts to heat and ionize the gas within the H II regions surrounding the first stars, as well as to photodissociate hydrogen molecules within the larger Lyman-Werner (LW) bubbles that surround these sources. Using a ray-tracing method in three-dimensional cosmological simulations, we self-consistently track the formation of, and radiative feedback from, individual stars in the formation of a protogalaxy. We compute in detail the H II regions of each of these sources, as well as the regions affected by their molecule-dissociating radiation. We follow the thermal, chemical, and dynamical evolution of the primordial gas as it becomes incorporated into the protogalaxy. While the IGM is, in general, optically thick to LW photons only over physical distances of greater than or similar to 30 kpc at redshifts z less than or similar to 20, the high molecule fraction that is built up in relic H ii regions and their increasing volume-filling factor renders even the local IGM optically thick to LW photons over physical distances of a few kiloparsecs. We find that Population III relic black holes may begin accreting efficiently after similar to 60 Myr from the time of their formation, when the photoheated relic H II region gas can cool and recollapse into the 106 M-circle dot minihalo which hosts the black hole. Population II.5 stars, postulated to have masses of the order of 10 M-circle dot, can also likely form from this recollapsing relic H ii region gas. Overall, we find that the local radiative feedback from Population III stars suppresses the star formation rate only slightly.