Measuring the Hubble constant using localized and nonlocalized fast radio bursts

¹ School of Astronomy and Space Science, Nanjing University, Nanjing 210093, China
² School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, China
³ Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi 830011, China
⁴ Xinjiang Key Laboratory of Radio Astrophysics, 150 Science1-Street, Urumqi 830011, China
⁵ Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210093, China
⁶ Department of Astronomy, University of Science and Technology of China, Hefei 230026, China

^⋆ Corresponding authors: fayinwang@nju.edu.cn: daizg@ustc.edu.cn

Received: 15 November 2024
Accepted: 30 April 2025

Abstract

The Hubble constant (H₀) is one of the most important parameters in the standard ΛCDM model. The measurements given by the main two methods show a gap larger than 4σ, which is known as Hubble tension. Fast radio bursts (FRBs) are extragalactic pulses with durations of milliseconds. They can be used as cosmological probes. We constrain H₀ using localized and nonlocalized FRBs. We first used 108 localized FRBs to constrain H₀ using the probability distributions of DM_host and DM_IGM from the IllustrisTNG simulation. Then, we used a Monte Carlo sampling to calculate the pseudo-redshift distributions of 527 nonlocalized FRBs from CHIME observations. The 108 localized FRBs yield a constraint of H₀ = 69.40_−1.97^+2.14 km s⁻¹ Mpc⁻¹, which lies between the early- and late-time values. The constraint of H₀ from nonlocalized FRBs yields H₀ = 68.81_−0.68^+0.68 km s⁻¹ Mpc⁻¹. This result indicates that the uncertainty on the constraint of H₀ drops to ∼1% when the number of localized FRBs is increased to ∼500. These uncertainties only include the statistical error. The systematic errors are also discussed and play a dominant role in the current sample.