Validating galaxy clustering models with Fixed & Paired and Matched-ICs simulations: application to Primordial Non-Gaussianities

Abstract

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

14+6 pages, 8+8 figures. Accepted in MNRAS

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Cited by in corpus (5)

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• PNG-UNITsims: Halo clustering response to primordial non-Gaussianities as a function of mass
• Primordial non-Gaussianity with Angular correlation function: Integral constraint and validation for DES
• Constraining primordial non-Gaussianity from the large scale structure two-point and three-point correlation functions
• Some Classes of Interacting Two-Fluid Model of the Expanding Universe