A measurement of Hubble’s constant using Fast Radio Bursts

We constrain the Hubble constant H₀ using Fast Radio Burst (FRB) observations from the Australian Square Kilometre Array Pathfinder (ASKAP) and Murriyang (Parkes) radio telescopes. We use the redshift-dispersion measure ('Macquart') relationship, accounting for the intrinsic luminosity function, cosmological gas distribution, population evolution, host galaxy contributions to the dispersion measure (DM_host), and observational biases due to burst duration and telescope beamshape. Using an updated sample of 16 ASKAP FRBs detected by the Commensal Real-time ASKAP Fast Transients (CRAFT) Survey and localized to their host galaxies, and 60 unlocalized FRBs from Parkes and ASKAP, our best-fitting value of H₀ is calculated to be 73+12₋₈ km s^-1 Mpc^-1. Uncertainties in FRB energetics and DM_host produce larger uncertainties in the inferred value of H0 compared to previous FRB-based estimates. Using a prior on H₀ covering the 67-74 km s^-1 Mpc^-1 range, we estimate a median DM_host=186⁺⁵⁹₋₄₈pc cm⁻³ , exceeding previous estimates. We confirm that the FRB population evolves with redshift similarly to the star-formation rate. We use a Schechter luminosity function to constrain the maximum FRB energy to be log₁₀E_max =41.26^+0.27_−0.22 erg assuming a characteristic FRB emission bandwidth of 1 GHz at 1.3 GHz, and the cumulative luminosity index to be γ=−0.95^+0.18_−0.15 . We demonstrate with a sample of 100 mock FRBs that H0 can be measured with an uncertainty of ±2.5 km s^-1 Mpc^-1, demonstrating the potential for clarifying the Hubble tension with an upgraded ASKAP FRB search system. Last, we explore a range of sample and selection biases that affect FRB analyses.