Constraining the ionized gas evolution with CMB-spectroscopic survey cross-correlation

摘要

We forecast the prospective constraints on the ionized gas model f gas ( z ) at different evolutionary epochs via the tomographic cross-correlation between kinetic Sunyaev–Zeldovich (kSZ) effect and the reconstructed momentum field at different redshifts. The experiments we consider are the Planck and CMB Stage-4 survey for CMB and the SDSS-III for the galaxy spectroscopic survey. We calculate the tomographic cross-correlation power spectrum, and use the Fisher matrix to forecast the detectability of different f gas ( z ) models. We find that for constant f gas model, Planck can constrain the error of f gas ( σ f gas ) at each redshift bin to ～0.2, whereas four cases of CMB-S4 can achieve σ f gas ～ 10 ? 3 . For f gas ( z ) = f gas , 0 / ( 1 + z ) model the error budget will be slightly broadened. We also investigate the model f gas ( z ) = f gas , 0 / ( 1 + z ) α . Planck is unable to constrain the index of redshift evolution, but the CMB-S4 experiments can constrain the index α to the level of σ α ～ 0.01 –0.1. The tomographic cross-correlation method will provide an accurate measurement of the ionized gas evolution at different epochs of the Universe.