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We study 21cm and Ly$\mathrm{\alpha}$ fluctuations, as well as H$\mathrm{\alpha}$, while distinguishing between Ly$\mathrm{\alpha}$ emission of galactic, diffuse, and scattered intergalactic medium (IGM) origin.
- Cross-correlation information about the state of the IGM is obtained, testing neutral versus ionized medium cases with different tracers in a seminumerical simulation setup.
- In order to pave the way toward constraints on reionization history and modeling beyond power spectrum information, we explore parameter dependencies of the cross-power signal between 21$\,$cm and Ly$\mathrm{\alpha}$, which displays a characteristic morphology and a turnover from negative to positive correlation at scales of a couple Mpc$^{-1}$.
- In a proof of concept for the extraction of further information on the state of the IGM using different tracers, we demonstrate the use of the 21$\,$cm and H$\mathrm{\alpha}$ cross-correlation signal to determine the relative strength of galactic and IGM emission in Ly$\mathrm{\alpha}$.