Complete history of the observable 21 cm signal from the first stars during the pre-reionization era

We present the first complete calculation of the history of the inhomogeneous 21 cm signal from neutral hydrogen during the era of the first stars. We use hybrid computational methods to capture the large-scale distribution of the first stars, whose radiation couples to the neutral hydrogen emission, and to evaluate the 21 cm signal from z similar to 15-35. In our realistic picture, large-scale fluctuations in the 21 cm signal are sourced by the inhomogeneous density field and by the Ly alpha and X-ray radiative backgrounds. The star formation is suppressed by two spatially varying effects: negative feedback provided by the Lyman-Werner radiative background, and supersonic relative velocities between the gas and dark matter. Our conclusions are quite promising: we find that the fluctuations imprinted by the inhomogeneous Ly alpha background in the 21 cm signal at z similar to 25 should be detectable with the Square Kilometre Array.