Better recipes for galaxy velocities at percent-level precision

Peculiar velocities distort galaxy redshift surveys, and modelling them accurately requires reliable expressions for velocity divergence power spectra. By recasting existing prescriptions using the clustering amplitude σ₁₂ instead of the conventional σ₈, the authors eliminate a spurious dependence on the Hubble parameter that contaminates non-linear models. Calibrated on multi-resolution N-body simulations and validated against independent runs spanning diverse cosmologies, the new fitting functions reach percent-level accuracy out to k ≈ 0.56 Mpc⁻¹. The result is a drop-in improvement for redshift-space distortion analyses in upcoming galaxy surveys.