Speaker
Description
The Square Kilometer Array (SKA-Mid) will map the post-reionization (post-EoR) Universe, via 21cm line intensity mapping (LIM) with accuracy and detail that was never possible. The SKA-Mid will first make the statistical detection of the 21cm LIM via power spectrum measurements, and the inference of astrophysics of the galaxies and Cosmology will follow with these detections. The power spectrum, by definition, can only completely characterize the statistical properties of a signal, which is a Gaussian random field. However, due to the non-linear clustering of the matter, the redshifted 21cm LIM signal from the post-EoR will be highly non-Gaussian. Additionally, the signal will contain the imprints of the primordial non-Gaussianity. Thus, to quantify the non-Gaussianity in the 21cm LIM signal, one has to consider higher-order statistics such as the bispectrum. However, residual foreground and systematics associated with the instrument will hinder a high signal-to-noise ratio detection of the 21cm auto bispectrum with fewer observational hours. One way to boost the signal-to-noise ratio is to do a cross-correlation measurement with various galaxy redshift surveys. Additionally, these cross-correlations have the potential to provide improved constraints on the Cosmological parameters. In this talk, I will discuss the prospects of the 21cm-galaxy cross-bispectrum, primarily focusing on forecasts with SKA-Mid and Euclid. We will show, for the first time, the nature of the 21cm-galaxy cross-bispectrum for all unique shapes and sizes of the bispectrum for various 21cm galaxy cross-combinations. Additionally, we will discuss the forecast on the detectability of the 21cm-galaxy cross bispectrum for a set of theoretical models of the post-EoR 21cm LIM signal with state-of-the-art simulations. These analyses highlight the potential of combining 21cm observations with complementary datasets of the large-scale structure in this era of precision Cosmology.
