Validating galaxy clustering models with fixed and paired and matched-ICs simulations: application to primordial non-Gaussianities

The Fix and Pair techniques were designed to generate simulations with reduced variance in the 2-point statistics by modifying Initial Conditions (ICs). In this paper we show that technique is also valid when initial conditions have local Primordial non-Gaussianities (PNG), parametrised $f_{\rm NL}$, without biasing but reducing significantly their variance. We how quantitatively use these test accuracy of galaxy/halo clustering models down a much uncertainty apply them standard model for halo presence PNG. Additionally, Matching stochastic part ICs two different cosmologies (Gaussian non-Gaussian) obtain large correlation between (2-point) can explicitly be used further reduce testing. For our reference analysis ($f_{\rm NL}=100$, $V=1 [h^{-1}{\rm Gpc}]^3$, $n= 2.5\times 10^{-4}[h^{-1}{\rm Mpc}]^{-3}$, $b=2.32$), an $\sigma(f_{\rm NL})=60$ simulation, whereas using Fixed [Fixed-Paired] it reduces NL})=12$ [$\sigma(f_{\rm NL})=12$]. When $\sigma (f_{\rm NL})=18$ case, NL})=8$ [$\sigma NL})=7$] [Fixed-Paired]. combination Fix, Match context PNG create effective volume incremented factor $\sim 70$ at given computational resources.