Prospects for cosmological research using hundred-meter-class radio telescopes: 21-cm intensity mapping survey strategies with QTT, JRT, and HRT

TL;DR

This paper evaluates the potential of three Chinese 100-meter-class radio telescopes for 21-cm intensity mapping to improve dark energy measurements, emphasizing the importance of redshift coverage up to z=1.

Contribution

It introduces a forecasting framework to assess the cosmological capabilities of QTT, JRT, and HRT telescopes for BAO/RSD measurements and dark energy constraints.

Findings

Combining all three telescopes improves dark energy parameter constraints.

Redshift coverage up to z=1 is essential for maximizing telescope potential.

The combined survey yields tighter constraints than DESI DR2.

Abstract

Understanding dark energy requires precision measurements of the expansion history of the universe and the growth of large-scale structure. The 21 cm intensity mapping (21 cm IM) technique enables rapid large-area surveys that can deliver these measurements. China is constructing three hundred-meter-class single-dish radio telescopes, including the QiTai 110 m Radio Telescope (QTT), the 120 m Jingdong Radio Telescope (JRT), and the 120 m Huadian Radio Telescope (HRT), whose designs are well suited for 21 cm IM cosmology. We use a Fisher-to-MCMC forecasting framework to evaluate the baryon acoustic oscillations / redshift space distortions (BAO/RSD) measurement capabilities of QTT, JRT, and HRT and propagate them to dark-energy constraints in the $w_0w_a$CDM model. Our results show that achieving a redshift coverage up to $z_{\mathrm{max}} = 1$ is crucial for fully realising the potential of hundred-meter-class single-dish telescopes for 21 cm cosmology. If all three telescopes carry out 21 cm IM surveys over the same redshift range up to $z_{\mathrm{max}}=1$ and combine their BAO/RSD measurements, QTT+JRT+HRT yield $\sigma(w_0)=0.094$ and $\sigma(w_a)=0.487$, providing tighter constraints than DESI DR2 results.