期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 455, 期 3, 页码 2945-2958出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stv2525
关键词
cosmology: theory; large-scale structure of Universe
资金
- Science and Technology Facilities Council [ST/L00075X/1]
- Science and Technology Facilities Council [ST/L00075X/1] Funding Source: researchfish
- STFC [ST/L00075X/1] Funding Source: UKRI
Accurate modelling of non-linearities in the galaxy bispectrum, the Fourier transform of the galaxy three-point correlation function, is essential to fully exploit it as a cosmological probe. In this paper, we present numerical and theoretical challenges in modelling the non-linear bispectrum. First, we test the robustness of the matter bispectrum measured from N-body simulations using different initial conditions generators. We run a suite of N-body simulations using the Zel'dovich approximation and second-order Lagrangian perturbation theory (2LPT) at different starting redshifts, and find that transients from initial decaying modes systematically reduce the non-linearities in the matter bispectrum. To achieve 1 per cent accuracy in the matter bispectrum at z <= 3 on scales k < 1 h Mpc(-1), 2LPT initial conditions generator with initial redshift z greater than or similar to 100 is required. We then compare various analytical formulas and empirical fitting functions for modelling the non-linear matter bispectrum, and discuss the regimes for which each is valid. We find that the next-to-leading order (one-loop) correction from standard perturbation theory matches with N-body results on quasi-linear scales for z >= 1. We find that the fitting formula in Gil-Marin et al. accurately predicts the matter bispectrum for z <= 1 on a wide range of scales, but at higher redshifts, the fitting formula given in Scoccimarro & Couchman gives the best agreement with measurements from N-body simulations.
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