Measuring Hubble constant using localized and unlocalized fast radio bursts

Abstract

The Hubble constant ($H_0$) is one of the most important parameters in the standard $\hat{\mathrm{I}}›\mathrm{CDM}$ model. The measurements given by the main two methods show a gap larger than $4\ddot{I}ƒ$, 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 $H_0$ using localized and nonlocalized FRBs. We first used 108 localized FRBs to constrain $H_0$ using the probability distributions of \DMhost and \DMIGM 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 $H_0=69.40_{-1.97}^{+2.14}$ $\mathrm{km}{\mathrm{s}}^{-1}\mathrm{Mp}{\mathrm{c}}^{-1}$, which lies between the early- and late-time values. The constraint of $H_0$ from nonlocalized FRBs yields $H_0=68.81_{-0.68}^{+0.68}$ $\mathrm{km}{\mathrm{s}}^{-1}\mathrm{Mp}{\mathrm{c}}^{-1}$. This result indicates that the uncertainty on the constraint of $H_0$ drops to $\sim 1\%$ when the number of localized FRBs is increased to $\sim 500$. These uncertainties only include the statistical error. The systematic errors are also discussed and play a dominant role in the current sample.

11 pages, 8 figures, 1 table, accepted for publication in A&A