CMB Anisotropies Resulting from Feedback-Regulated Inhomogeneous Reionization

We calculate the secondary anisotropies in the cosmic microwave background (CMB) produced by inhomogeneous reionization from simulations in which the effects of radiative and stellar feedback effects on galaxy formation have been included. This allows us to determine self-consistently the beginning (zi≈30), the duration (δz≈20) and the (non-linear) evolution of the reionization process for a critical density cold dark matter (CDM) model. In addition, from the simulated spatial distribution of ionized regions, we are able to calculate the evolution of the two-point ionization correlation function, C, and obtain the power spectrum of the anisotropies, Cℓ, in the range 5000<ℓ<106. The power spectrum has a broad maximum around ℓ≈30 000, where it reaches the value 2×10−12. We also show that the ionization correlation function C is not Gaussian, but at separation angles θ≲10−4 rad it can be approximated by a modified Lorentzian shape; at larger separations an anticorrelation signal is predicted for both C and C(θ). Detection of signals as above will be possible with future millimetre-wavelength interferometers like the Atacama Large Millimeter Array (ALMA), which appears as an optimum instrument to search for signatures of inhomogeneous reionization.