Description
We present measurements of H I galaxy clustering for a combined sample of ALFALFA and FASHI galaxies, hereafter AF+FS, and compare them with mock galaxy catalogs derived from the MultiDark--Planck simulation, hereafter MDPL. The analysis used the two-point correlation function, $\omega_p(r_p)/r_p$, in differential $\log W_{50}$ bins to test whether the clustering length $r_0$ increases with the observed linewidth proxy $W_{50}$, while $W_{50}$ was calculated for MDPL. We found a positive $r_0-\log W_{50}$ relation in AF+FS, the full MDPL, and an observed distribution-matched mock, MDPL$_{\rm sub}$. The latter was constructed by downsampling the full mock in the joint distance-$-\log W_{50}$ plane to match the observed distribution while preserving galaxy positions. The inferred trends were consistent within the current uncertainties, with AF+FS and MDPL$_{\rm sub}$ showing good agreement. Additional monopole, threshold, and halo-spin parameter split tests are presented as robustness checks.
