‘Negative’ intensity patches in angular variations of the cosmic microwave background as a probe of the period of reionization
Abstract
The observational tests for the period of reionization of the Universe are discussed. We show that this period can be observed as negative intensity patches of the cosmic microwave background (CMB) radiation with an amplitude of and the angular sizes of in the wavelength range of . The expected number density and frequency dependence of the amplitude permit us to recognize this effect and to distinguish it from the noise. This method, applied to the small-scale variations of the CMB temperature, complements the traditional spectral approach well. The number density and the amplitude of observed ‘negative’ intensity patches depend upon the redshift of reionization, which allows us to estimate this redshift roughly. The ionized bubbles formed just before the period of reionization could also be seen as the highest peaks. The expected results are sensitive to the Jeans scale at the period of reionization, and also to the small-scale shape of the primordial power spectrum and the mass of dark matter particles.