Duration Of Reionization Research Articles

The Kinetic Sunyaev‐Zel’dovich Effect from Reionization

During the epoch of reionization, local variations in the ionized fraction (patchiness) imprint arcminute-scale temperature anisotropies in the cosmic microwave background through the kinetic Sunyaev–Zel’dovich (kSZ) effect. We employ an analytic model of reionization devised by Furlanetto and coworkers to calculate the kSZ anisotropies for patchy reionization. We find that the angular power spectrum of the kSZ anisotropies depends strongly on the size distribution of the HII bubbles and on the duration of reionization. In addition, we show that upcoming measurements of the kSZ effect should be able to distinguish between several popular reionization scenarios. In particular, the amplitude of the patchy power spectrum for reionization scenarios in which the IGM is significantly ionized by Population III stars (or by mini-quasars/decaying particles) can be larger (or smaller) by over a factor of 3 than the amplitude in more traditional reionization histories (with temperature anisotropies that range between 0.5 and 3 μK at l = 5000).

Effects of small-scale structure on the progress and duration of reionization

The propagation of cosmological ionization fronts during the reionization of the universe is strongly influenced by small-scale (∼ kpc) gas inhomogeneities caused by struc- ture formation. In this paper we study this important effect by performing detailed radiative- hydrodynamic simulations of photoevaporation of cosmological minihalos (MHs) and incorpo- rating the results into a semi-analytical model of reionization, which also includes the effect of mean intergalactic medium (IGM) clumping and the nonlinear clustering of minihalos. We find that small-scale structures have a significant effect on the process of reionization, slowing it down and extending it in time. This can help in understanding the recent observations by the Wilkinson Microwave Anisotropy Probe (WMAP) satellite, which point to an early and extended reionization epoch.