HI intensity mapping with MeerKAT: forecast for delay power spectrum measurement using interferometer mode

TL;DR

This study evaluates MeerKAT's potential for HI intensity mapping in interferometer mode to measure the delay power spectrum and constrain dark energy models, highlighting the importance of survey design and observational time.

Contribution

It introduces a forecast method for MeerKAT HI IM observations using the delay spectrum approach to estimate the power spectrum and assess dark energy constraints.

Findings

Fractional errors decrease with longer observation times.

Survey field selection impacts measurement precision.

Limited dark energy constraints from MeerKAT HI IM alone.

Abstract

Neutral hydrogen (HI) intensity mapping (IM) surveys are considered a promising tool for investigating the expansion history of the Universe. In this work, we explore the potential of MeerKAT HI IM observations in interferometer mode to estimate the power spectrum and constrain cosmological parameters within typical dark energy models. We employ an approach called the "delay spectrum," which allows us to separate the weak HI signal from foreground contamination in the frequency domain. Our findings indicate that the choice of survey fields significantly impacts the fractional errors on the power spectrum ($\Delta P/P$) within a limited observational time of 10 hours. As the integration time increases from 10 hours to 10,000 hours, $\Delta P/P$ progressively decreases until cosmic variance begins to dominate. For a total observation time of 10,000 hours, the lowest $\Delta P/P$ at low $k$ can be achieved by tracking 100 points for MeerKAT L-band (900-1200 MHz) and 10 points for MeerKAT UHF-band (580-1000 MHz). Next, we assess the performance of HI IM in constraining typical dark energy models. We find that MeerKAT HI IM survey in interferometer mode demonstrates limited capability in constraining the dark-energy equation of state, even when combined with Planck data.