Cosmological constraints from the EFT power spectrum and tree-level bispectrum of 21cm intensity maps

TL;DR

This paper assesses the potential of 21cm intensity maps, using the EFT power spectrum and bispectrum, to improve cosmological parameter constraints and break degeneracies in next-generation surveys.

Contribution

It introduces the use of the EFT-based bispectrum at tree level in 21cm intensity mapping analysis for the first time.

Findings

Bispectrum adds significant constraining power.

Potential to break parameter degeneracies.

Improved dark energy and gravity constraints.

Abstract

We explore the information content of 21cm intensity maps in redshift space using the 1-loop Effective Field Theory power spectrum model and the bispectrum at tree level. The 21cm signal contains signatures of dark matter, dark energy and the growth of large-scale structure in the Universe. These signatures are typically analyzed via the 2-point correlation function or power spectrum. However, adding the information from the 3-point correlation function or bispectrum will be crucial to exploiting next-generation intensity mapping experiments. The bispectrum could offer a unique opportunity to break key parameter degeneracies that hinder the measurement of cosmological parameters and improve on the precision. We use a Fisher forecast analysis to estimate the constraining power of the HIRAX survey on cosmological parameters, dark energy and modified gravity.