Prospects for cosmological research with the FAST array: 21-cm intensity mapping survey observation strategies

TL;DR

This paper evaluates the potential of the FAST radio telescope, especially with technological upgrades and array configurations, to perform precise 21-cm intensity mapping for cosmological research, comparable to existing methods.

Contribution

It proposes specific upgrades and an array configuration for FAST that could significantly enhance its cosmological measurement capabilities.

Findings

Wide-band receiver upgrade enables higher precision measurements.

A FAST array (FASTA) improves cosmological constraints over single FAST.

FASTA can achieve constraints comparable to combined current cosmological data.

Abstract

Precise cosmological measurements are essential for understanding the evolution of the universe and the nature of dark energy. The Five-hundred-meter Aperture Spherical Telescope (FAST), the most sensitive single-dish radio telescope, has the potential to provide the precise cosmological measurements through neutral hydrogen 21-cm intensity mapping sky survey. This paper primarily explores the potential of technological upgrades for FAST in cosmology. The most crucial upgrade begins with equipping FAST with a wide-band receiver ($0 < z < 2.5$). This upgrade can enable FAST to achieve higher precision in cosmological parameter estimation than the Square Kilometre Array Phase-1 Mid frequency. On this basis, expanding to a FAST array (FASTA) consisting of six identical FASTs would offer significant improvements in precision compared to FAST. Additionally, compared with the current results from the data combination of cosmic microwave background, baryon acoustic oscillations (optical galaxy surveys), and type Ia supernovae, FASTA can provide comparable constraints. Specifically, for the dark-energy equation-of-state parameters, FASTA can achieve $\sigma(w_0) = 0.09$ and $\sigma(w_a) = 0.33$.