Speaker
Description
The HI 21-cm optical depth can be significantly high in regions with dense neutral hydrogen and low spin temperature during CD. Therefore, during this epoch the commonly used equation for calculating HI 21-cm differential brightness temperature considering linear approximation of optical depth tends to overestimate the signal compared to the signal using exact equation. These corrections will change the statistics of the signal considerably in particular for skewness, power spectrum and bi-spectrum. We study the numerical simulations we have used to accurately model the signal as well as the optical depth distribution during CD. There would be a suppression in the signal while using the accurate model of the signal. We see from our simulation high optical depth points will reside in the tail of the differential brightness temperature distribution which will lead to non-Gaussianity. Therefore, we discuss how the statistics will change using accurate model of the signal in comparison to linearly approximated one.
