H <scp>i</scp> intensity mapping with MeerKAT: forecast for delay power spectrum measurement using interferometer mode

Abstract

ABSTRACT Neutral hydrogen (H i) 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 H i 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 H i 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 (ΔP/P) within a limited observational time of 10 h. As the integration time increases from 10–10 000 h, ΔP/P progressively decreases until cosmic variance begins to dominate. For a total observation time of 10 000 h, the lowest ΔP/P at low k can be achieved by tracking 100 points for the MeerKAT L band (900–1200 MHz) and 10 points for the MeerKAT UHF band (580–1000 MHz). Next, we assess the performance of H i IM in constraining typical dark-energy models. We find that the MeerKAT H i IM survey in interferometer mode demonstrates limited capability in constraining the dark-energy equation of state, even when combined with Planck data. Our analysis serves as a valuable guide for future MeerKAT observations in H i IM surveys.