Toward an accurate Dark Matter power spectrum beyond BAO scales

TL;DR

This paper introduces a new approximation for the non-linear Dark Matter power spectrum that achieves high accuracy beyond BAO scales, validated against N-body simulations across various redshifts and scales.

Contribution

A novel approximate expression for the non-linear Dark Matter power spectrum that extends accuracy beyond BAO scales, based on an improved kernel function approximation in Standard Perturbation Theory.

Findings

Achieves better than 2% accuracy up to k=1.0 h/Mpc at z=3.0

Maintains within 10% accuracy up to k=0.8 h/Mpc at z=0.35

Validates the approximation against N-body simulation results

Abstract

We propose a new approximated expression for non-linear Dark Matter power spectrum much beyond BAO scales. The proposed expression agrees with the result of N-body simulation with the accuracy better than 2 % up to k=1.0 [h/Mpc] and k=0.7 [h/Mpc] at z=3.0 and z=1.0, respectively. Even at z=0.35, the accuracy remains within 10 % up to k=0.8 [h/Mpc]. In doing so, we used an approximation for the kernel functions used in the Standard Perturbation Theory (SPT) which is also used to prove the Reg PT proposed by Bernardeau et al. (2011).