Speaker
Description
The 21-cm signal from the Epoch of Reionization (EoR) traces the neutral hydrogen present in the IGM. The patchy ionization of neutral Hydrogen (HI) permeating Inter-galactic medium (IGM) makes the 21-cm signal highly non-Gaussian. The ionized bubbles, once formed, generate secondary anisotropies in the observed CMB signal. Patchy screening ($\tau_{es}$) is one such anisotropy that arises when CMB photons Thompson scatter off the free electrons, resulting in a new polarization in the signal. Previous studies have looked into the prospects of cross-correlating this patchy screening effect with the 21-cm signal. However, using a foreground wedge filter on the 21-cm maps removes low $k_{\parallel}$ modes in this signal, and $\tau_{es}$ is an integrated line-of-sight effect, i.e. only $k_{\parallel}=0$ mode exists. In order to avoid mismatched Fourier space coverage of the two signals, we build a 21cm-21cm-$\tau_{es}$ estimator. This estimator encodes important information about the reionization history and is also expected to survive the wedge filter through mode-coupling induced by higher-order correlations. Additionally, we present forecasts for the detection of this signal in future surveys.
| Other topic / keywords: | Epoch of Reionization |
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