2026/05/12 by M. Douspis, A. Gorce, S. Ilić +5
Physics and Astronomy · #Galaxies: Formation, Evolution, Phenomena #Cosmology and Gravitation Theories #Radio Astronomy Observations and Technology
paper · pdf · doi:10.1051/0004-6361/202660915
The epoch of reionisation is a key phase in cosmic history, but its detailed evolution remains poorly constrained by current cosmic microwave background (CMB) observations. We investigated whether the kinetic Sunyaev--Zel’dovich (kSZ) effect can discriminate among reionisation histories consistent with current large--scale CMB constraints. Using histories derived from data, we computed the corresponding kSZ angular power spectra within an analytical framework. The allowed histories fall into two broad classes, `late' and `early' start, yielding distinct kSZ signatures that remain clearly separable even when accounting for modelling uncertainties in both the reionisation scenario, xe(z), and the properties of early galaxies. Current kSZ measurements (∼0--3 μK2) tend to favour `late' reionisation models but are not yet sensitive enough to definitively distinguish between the scenarios -- a measurement of the kSZ power spectrum at ell ∼ 2000 with ∼0.4 μK2 sensitivity, achievable in the coming years, will be sufficient to do so. This work demonstrates that CMB data alone can constrain the reionisation midpoint z_ Planck with extremely narrow error bars (7.94<z_ <8.17), even when effectively marginalising over modelling uncertainties. re