Speaker
Description
The 21-cm signal arising from the spin-flip transition from neutral hydrogen (HI) in the intergalactic medium (IGM) serves as a powerful probe of the Epoch of Reionization (EoR), the period during which the first luminous sources were formed and Universe went through a phase transition from being neutral to ionized. This signal traces the distribution and properties of the IGM in this critical phase change of the cosmic history. More importantly this field exhibits a significantly strong non-Gaussianity due to the complex distribution and growth of ionized regions, which is tied to the various astrophysical processes in the IGM and within the sources. As a result, the standard 21-cm power spectrum fails to capture all the relevant statistical information hidden in this field. While higher-order statistics, such as the bispectrum, can provide additional insights, they are computationally intensive and often difficult to interpret. This work investigates the application of marked statistics as an alternative approach to characterize the EoR 21-cm field. By employing non-linear transformations and assigning weights based on the local property in the map, the contributions from distinct types of fluctuations in that environment can be modified, allowing for targeted analysis of specific features. In particular, up-weighting specific field properties amplifies their corresponding fluctuations, improving the ability of the marked power spectrum to capture the relevant information content. Through this project, we demonstrated that it is possible to construct meaningful transformations that render the marked power spectrum a more optimal summary statistic. We show that this approach provides a computationally efficient framework for extracting non-Gaussian information and enables a more detailed statistical description of the 21-cm signal. The project further explores different forms of mark functions and their impact on the resulting statistics, with the broader goal of improving our understanding of the EoR.
