The optical depth $\tau$ is the least well determined parameter in standard model of cosmology, and one whose precise value important for both understanding reionization inferring fundamental physics from cosmological measurements. We forecast how future epoch experiments could constraint using a symmetries-based bias expansion that highlights special role played by anisotropies power spectrum ...

ABSTRACT One of the critical challenges facing imaging studies 21-cm signal at Epoch Reionization (EoR) is separation astrophysical foreground contamination. These foregrounds are known to lie in a wedge-shaped region (k?, k?) Fourier space. Removing these modes excises grave expense image fidelity, since cosmological information also removed by wedge filter. However, EoR non-Gaussian, meaning ...