Dispersion Measure Distribution of Unlocalized Fast Radio Bursts as a Probe of the Hubble Constant

TL;DR

This paper demonstrates that the dispersion measure distribution of unlocalized fast radio bursts can independently constrain the Hubble constant without redshift data, offering a new cosmological probe.

Contribution

It introduces a novel method to estimate the Hubble constant using unlocalized FRBs' DM distribution, achieving the first such measurement without redshift information.

Findings

Derived H_0 = 73.8^{+14.0}_{-12.3} km/s/Mpc from 2124 FRBs

Uncertainty reduced to 9% when breaking degeneracy with energy cutoff

First H_0 measurement solely from unlocalized FRB DM distribution

Abstract

We present constraints on the Hubble constant ($H_0$) derived from the observed dispersion measure (DM) distribution of unlocalized fast radio bursts (FRBs). While localized FRBs with redshift measurements have been used to investigate the Hubble tension, their sample remains limited. Here we demonstrate that unlocalized FRBs -- which are far more numerous -- can independently constrain $H_0$ without requiring redshift information, as cosmic expansion imprints itself on their DM distribution. Analyzing a selected sample of 2124 unlocalized FRBs from the CHIME Catalog II, we obtain $H_0 = 73.8^{+14.0}_{-12.3}~\mathrm{km\,s^{-1}\,Mpc^{-1}}$ at the $1\sigma$ confidence level, corresponding to an uncertainty of about 18%. Breaking the degeneracy between $H_0$ and the characteristic cutoff energy $E_*$ of the FRB isotropic energy distribution would reduce this uncertainty to 9%. This work constitutes the first $H_0$ measurement derived solely from the DM distribution of unlocalized FRBs, highlighting their potential as a new cosmological probe. Future joint analyses with localized FRBs promise even tighter constraints.