Radio views of cosmic reionization

We use numerical simulations of cosmic reionization and radiative processes related to the HI 21-cm emission line to produce synthetic radio maps as seen by next-generation telescopes that will operate at low radio frequencies (e.g. the Low Frequency Array, LOFAR). Two different scenarios, in which the end of reionization occurs early (z ≈ 13) or late (z ≈ 8) depending on the initial mass function (IMF) of the first stars and ionizing photon escape fraction, have been explored. For each of these models we produce synthetic H I 21-cm emission maps by convolving the simulation outputs with the provisional LOFAR sampling function in the frequency range 76-140 MHz. If reionization occurs late, LOFAR will be able to detect individual H I structures on arcmin scales, emitting at a brightness temperature of ≈35 mK as a 3σ signal in about 1000 h of observing time. In the case of early reionization, the detection would be unlikely, due to decreased sensitivity and increased sky temperatures. These results assume that ionospheric, interference and foreground issues are fully under control. © 2006 The Authors. Journal compilation © 2006 RAS.