HI intensity mapping with the MIGHTEE survey: power spectrum estimates

TL;DR

This paper demonstrates that the MeerKAT telescope, using intensity mapping with the MIGHTEE survey, can statistically detect neutral hydrogen in the post-reionization universe and measure the HI power spectrum on quasi-linear scales, providing valuable cosmological insights.

Contribution

It introduces a simulation pipeline for HI intensity mapping with MeerKAT and forecasts its capability to measure the HI power spectrum at $z=0.27$, highlighting the potential for cosmological studies.

Findings

High sensitivity detection of HI with SNR > 7 at $k=0.49$ Mpc$^{-1}$

Qualitative agreement between pipeline estimates and actual MIGHTEE data

Feasibility of probing cosmological parameters using the HI power spectrum

Abstract

Intensity mapping (IM) with neutral hydrogen is a promising avenue to probe the large scale structure of the Universe. In this paper, we demonstrate that using the 64-dish MeerKAT radio telescope as a connected interferometer, it is possible to make a statistical detection of HI in the post-reionization Universe. With the MIGHTEE (MeerKAT International GHz Tiered Extragalactic Exploration) survey project observing in the L-band ($856 < \nu < 1712$ MHz, $z < 0.66$), we can achieve the required sensitivity to measure the HI IM power spectrum on quasi-linear scales, which will provide an important complementarity to the single-dish IM MeerKAT observations. We present a purpose-built simulation pipeline that emulates the MIGHTEE observations and forecast the constraints that can be achieved on the HI power spectrum at $z = 0.27$ for $k > 0.3$ $\rm{Mpc}^{-1}$ using the foreground avoidance method. We present the power spectrum estimates with the current simulation on the COSMOS field that includes contributions from HI, noise and point source models constructed from the observed MIGHTEE data. The results from our \textit{visibility} based pipeline are in qualitative agreement to the already available MIGHTEE data. This paper demonstrates that MeerKAT can achieve very high sensitivity to detect HI with the full MIGHTEE survey on quasi-linear scales (signal-to-noise ratio $> 7$ at $k=0.49$ $\rm{Mpc}^{-1}$) which are instrumental in probing cosmological quantities such as the spectral index of fluctuation, constraints on warm dark matter, the quasi-linear redshift space distortions and the measurement of the HI content of the Universe up to $z\sim 0.5$.