Extracting bias using the cross-bispectrum: An EoR and 21 cm-[CII]-[CII] case study

Understand

The amplitude of redshifted 21 cm fluctuations during the Epoch of Reionization (EoR) is expected to show a distinctive "rise and fall" behavior with decreasing redshift as reionization proceeds.

• On large scales (k <~ 0.1 Mpc^{-1}) this can mostly be characterized by evolution in the product of the mean 21 cm brightness temperature and a bias factor, b_21(z).
• This quantity evolves in a distinctive way that can help in determining the average ionization history of the intergalactic medium (IGM) from upcoming 21 cm fluctuation data sets.
• Here we consider extracting <T_21> b_21(z) using a combination of future redshifted 21 cm and [CII] line-intensity mapping data sets.