Estimating the Feasibility of 21cm-Ly$\alpha$ Synergies using the Hydrogen Epoch of Reionization Array

Abstract

Cross-correlating 21cm and Ly$\alpha$ intensity maps of the Epoch of Reionization (EoR) promises to be a powerful tool for exploring the properties of the first galaxies. Next-generation intensity mapping experiments such as the Hydrogen Epoch of Reionization Array (HERA) and SPHEREx will individually probe reionization through the power spectra of the 21cm and Ly$\alpha$ lines respectively, but will be limited by bright foregrounds and instrumental systematics. Cross-correlating these measurements could reduce systematics, potentially tightening constraints on the inferred astrophysical parameters. In this study, we present forecasts of cross-correlation taking into account the effects of exact uv-sampling and foreground filtering to estimate the feasibility of HERAxSPHEREx making a detection of the 21cm-Ly$\alpha$ cross-power spectrum. We also project the sensitivity of a cross-power spectrum between HERA and the proposed next-generation Cosmic Dawn Intensity Mapper. By isolating the sources of uncertainty, we explore the impacts of experimental limitations such as foreground filtering and Ly$\alpha$ thermal noise uncertainty have on making a detection of the cross-power spectrum. We then implement this strategy in a simulation of the cross-power spectrum and observational error to identify redshifts where fiducial 21cmFAST models predict the highest signal-to-noise detection ($z\sim 8$). We conclude that detection of the SPHEREx-HERA cross-correlation will require an optimistic level of 21cm foreground filtering, as well as deeper thermal noise integrations due to a lack of overlapping sensitive modes but for CDIM with its larger range of scales and lower noise forecast detection levels, may be possible even with stricter 21cm foreground filtering.

11 pages, 6 figures, Accepted by MNRAS

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Cited by in corpus (5)

• Hydrogen Epoch of Reionization Array (HERA) Phase II Deployment and Commissioning
• LIMFAST. II. Line Intensity Mapping as a Probe of High-Redshift Galaxy Formation
• Exploring the cosmic dawn and epoch of reionization with 21cm line
• Revisiting the [C II]${}_{158\mu \text{m}}$ line-intensity mapping power spectrum from the EoR using non-uniform line-luminosity scatter
• Field-level Reconstruction from Foreground-Contaminated 21-cm Maps