Speaker
Description
The Hubble constant (H₀) characterizes the present-day expansion rate of the universe. However, despite the significant decrease in measurement uncertainties, a discrepancy of more than 4𝜎, known as the Hubble tension, exists between measurements from the Cosmic Microwave Background (CMB), which yields H₀ = 67.66 ± 0.42 km s⁻¹ Mpc⁻¹ under the ΛCDM model, and Cepheid-calibrated Type Ia supernovae (SNe Ⅰa), which gives 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, combined with photometric redshifts from DESI. Precise localization is challenging due to the millisecond durations of FRBs and the limited angular resolution of wide-field radio surveys such as CHIME, which often results in large positional uncertainties. 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 constrain the value of H₀.
| Participate the oral/poster presentation award competition | Yes |
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