The Kinetic Sunyaev-Zel'dovich effect as a probe of the physics of cosmic reionization: the effect of self-regulated reionization

摘要

We calculate the angular power spectrum of the Cosmic Microwave Backgroundud(CMB) temperature fluctuations induced by the kinetic Sunyaev-Zel'dovich (kSZ)udeffect from the epoch of reionization (EOR). We use detailed N-body+radiativeudtransfer simulations to follow inhomogeneous reionization of the intergalacticudmedium (IGM). For the first time we take into account the "self-regulation" ofudreionization: star formation in low-mass dwarf galaxies (10^8 M_sun lesssim Mudlesssim 10^9 M_sun) or minihalos (10^5 M_sun lesssim M lesssim 10^8udM_sun) is suppressed if these halos form in the regions that were alreadyudionized or Lyman-Werner dissociated. Some previous work suggested that theudamplitude of the kSZ power spectrum from the EOR can be described by audtwo-parameter family: the epoch of half ionization and the duration ofudreionization. However, we argue that this picture applies only to simple formsudof the reionization history which are roughly symmetric about theudhalf-ionization epoch. In self-regulated reionization, the universe begins toudbe ionized early, maintains a low level of ionization for an extended period,udand then finishes reionization as soon as high-mass atomically-cooling halosuddominate. While inclusion of self-regulation affects the amplitude of the kSZudpower spectrum only modestly (sim 10 %), it can change the duration ofudreionization by a factor of more than two. We conclude that the simpleudtwo-parameter family does not capture the effect of a physical, yet complex,udreionization history caused by self-regulation. When added to theudpost-reionization kSZ contribution, our prediction for the total kSZ powerudspectrum is below the current upper bound from the South Pole Telescope.udTherefore, the current upper bound on the kSZ effect from the EOR is consistentudwith our understanding of the physics of reionization.