A new measurement of the Hubble constant using Fast Radio Bursts

TL;DR

This paper demonstrates that fast radio bursts (FRBs) can be used to measure the Hubble constant independently, with current data providing a preliminary estimate and future data promising high-precision results that could resolve existing cosmological tensions.

Contribution

First measurement of the Hubble constant using FRB dispersion measures with identified host galaxies, showing potential for high-precision cosmology with future FRB observations.

Findings

Current FRB data yields H0 = 62.3 ± 9.1 km/s/Mpc.

A few hundred FRBs with redshifts can achieve 1% accuracy in H0.

Future FRB observations can resolve the H0 tension without other cosmological probes.

Abstract

Fast radio bursts (FRBs) are very short and bright transients visible over extragalactic distances. The radio pulse undergoes dispersion caused by free electrons along the line of sight, most of which are associated with the large-scale structure (LSS). The total dispersion measure therefore increases with the line of sight and provides a distance estimate to the source. We present the first measurement of the Hubble constant using the dispersion measure -- redshift relation of FRBs with identified host counterpart and corresponding redshift information. A sample of nine currently available FRBs yields a constraint of $H_0 = 62.3 \pm 9.1 \,\rm{km} \,\rm{s}^{-1}\,\rm{Mpc}^{-1}$, accounting for uncertainty stemming from the LSS, host halo and Milky Way contributions to the observed dispersion measure. The main current limitation is statistical, and we estimate that a few hundred events with corresponding redshifts are sufficient for a per cent measurement of $H_0$. This is a number well within reach of ongoing FRB searches. We perform a forecast using a realistic mock sample to demonstrate that a high-precision measurement of the expansion rate is possible without relying on other cosmological probes. FRBs can therefore arbitrate the current tension between early and late time measurements of $H_0$ in the near future.