1. The YLZ relation in Equation (1) depends on three unknown astrophysical parameters (ζ_e, γ_th, R) that are assumed to follow a lognormal distribution with fixed scatter derived from only 4 sources. Given that FRBs with PRS associations are inherently biased toward extreme RM values (Table 1 shows RM ranging from ~340 to 1.4×10^5 rad m^-2), how can you justify that this small, highly biased sample adequately represents the intrinsic scatter of the YLZ relation? The σ=1/3 ln(10) scatter from Bruni et al. (2025) may underestimate the true uncertainty when applied to a broader population.
2. In Section 3, you use a fixed DM_halo = 55 pc cm^-3 and apply a selection criterion DM_obs – DM_MW ≥ 80 pc cm^-3. However, the uncertainty in DM_halo (30-80 pc cm^-3) is comparable to the IGM contribution at low redshifts. Your joint analysis claims improvement from ΔH0/H0 ~4% to 2.9% with matched samples, but this appears driven by the assumed lognormal host distribution (Equation 9) which was calibrated from only 8 FRBs (Macquart et al. 2020). Since the DMhost distribution strongly affects the DM-z likelihood, doesn’t this artificially inflate the significance of the joint constraints?