SAIP2025

Bispectrum correlations of HI intensity mapping and large-scale structure surveys

Not scheduled

1h

Solomon Mahlangu House (University of the Witwatersrand, Johannesburg)

Oral Presentation Track D1 - Astrophysics Astrophysics & Space Science

Speaker

Moumita Aich (University of Witwatersrand)

Description

Neutral hydrogen (HI) intensity mapping (IM) experiments
probe the large-scale structure of the universe through the integrated
redshifted 21-cm line emission from unresolved sources of neutral
hydrogen. Optical surveys also probe the large-scale structure of the
universe with much higher precision and depth by mapping the galaxy
distribution. In this article, we study the cross-correlations of the
HI IM field from HIRAX (Hydrogen Intensity and Real-time Analysis
eXperiment) with the galaxy density and cosmic shear fields from the
Rubin observatory large-scale structure survey, laying down the tools
to do parameter forecasts and study constraints on the neutral
hydrogen fraction, galaxy bias, and cosmological parameters.
Astrophysical foregrounds limit the long-wavelength line-of-sight HI
modes, reducing the constraining power of these cross-correlations. We
introduce bispectrum estimators, specifically HI-HI-galaxy density and
HI-HI-shear cross bispectra estimators, to recover modes lost in the
foreground subtraction process and improve the parameter constraints.