Speaker
Description
The Hubble constant (H₀) characterizes the present-day expansion rate of the universe. However, despite the significant decrease in measurement uncertainties, the discrepancy of more than 4𝜎 remains between two main methods —the Cosmic Microwave Background (CMB) and Cepheid-calibrated Type Ia supernovae (SNe Ⅰa), known as the Hubble tension. To address the Hubble tension, where the ΛCDM model yields a value of H₀ = 67.66 ± 0.42 km s⁻¹ Mpc⁻¹ while Cepheid-calibrated Type Ia supernovae give H₀ = 73.04 ± 1.04 km s⁻¹ Mpc⁻¹, it is essential to develop independent methods for measuring the Hubble constant. Fast radio bursts (FRBs) are short-lived, intense extragalactic signals that last only a few milliseconds in the radio band. The dispersion measure (DM) of an FRB is related to the integrated free-electron density along the line of sight and is correlated with redshift. This relation, known as the Macquart relation, links DM to redshift by tracing the number of free electrons along the path, thereby providing a probe of the distance-redshift relation and enabling constraints on the H₀. We present a new approach using FRB data from CHIME Catalog 2, including both localized and non-localized FRBs, with photometric redshifts from DESI. Our analysis is based on 4539 FRBs. We apply the Probabilistic Association of Transients to their Host (PATH) method to estimate the host-galaxy redshift probabilities for non-localized FRBs. We then derive the Macquart relation to estimate the value of H₀.