Expansion series of the pairwise velocity generating function and its implications on redshift space distortion modeling

摘要

The pairwise velocity generating function G has a deep connection with both the pairwise velocity probability distribution function and modeling of redshift space distortion(RSD).Its implementation into RSD modeling is often faciliated by expansion into a series of pairwise velocity moments(v^(n)_(12))-Motivated by the logrithmic transformation of the cosmic density field,we investigate an alternative expansion into series of pairwise velocity cumulants(v^(n)_(12))c.We numerically evaluate the convergence rate of the two expansions,with three 30723 particle simulations of the CosmicGrowth N-body simulation series.(1)We find that the cumulant expansion performs significantly better,for all the halo samples and redshifts investigated.(2)For modeling RSD at k||