Abstract

Contributed Talk - Splinter LIM   (MW-2050)

One with HI: Modelling HI Intensity Mapping one-point statistics including systematics

Bernhard Vos Gines, Cora Uhlemann
Bielefeld University

Neutral hydrogen (HI) traces the dark matter distribution of the Universe. Upcoming surveys such as the Square Kilometre Array Observatory (SKAO) will trace the neutral hydrogen up to z~6 using several detection techniques including Intensity Mapping, which offers a unique window to explore the post-reionization Universe. Beyond two-point statistics promise to extract additional non-Gaussian information but require an accurate modelling of observational systematics such as foregrounds and the telescope beam. This work develops a theoretical model for the HI one-point probability density function (PDF) in spherical cells based on large-deviation statistics and spherical collapse for dark matter along with a tracer bias and stochasticity parameterisation. The foreground removal and telescope beam effects are modelled at the level of the variance and validated against high-resolution simulations. We show that, despite these observational systematics, the HI PDF is able to capture additional non-Gaussian information from HI intensity maps compared to the power spectrum and can thus tighten constraints on cosmological parameters.