Accurate halo-galaxy mocks from automatic bias estimation and particle mesh gravity solvers

Vakili, M.; Kitaura, F.-Sh.; Feng, Yu; Yepes, Gustavo; Zhao, Cheng; Chuang, Chia-Hsun; Hahn, ChangHoon
Bibliographical reference

Monthly Notices of the Royal Astronomical Society, Volume 472, Issue 4, p.4144-4154

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Reliable extraction of cosmological information from clustering measurements of galaxy surveys requires estimation of the error covariance matrices of observables. The accuracy of covariance matrices is limited by our ability to generate sufficiently large number of independent mock catalogues that can describe the physics of galaxy clustering across a wide range of scales. Furthermore, galaxy mock catalogues are required to study systematics in galaxy surveys and to test analysis tools. In this investigation, we present a fast and accurate approach for generation of mock catalogues for the upcoming galaxy surveys. Our method relies on low-resolution approximate gravity solvers to simulate the large-scale dark matter field, which we then populate with haloes according to a flexible non-linear and stochastic bias model. In particular, we extend the patchy code with an efficient particle mesh algorithm to simulate the dark matter field (the fastpm code), and with a robust MCMC method relying on the emcee code for constraining the parameters of the bias model. Using the haloes in the BigMultiDark high-resolution N-body simulation as a reference catalogue, we demonstrate that our technique can model the bivariate probability distribution function (counts-in-cells), power spectrum and bispectrum of haloes in the reference catalogue. Specifically, we show that the new ingredients permit us to reach percentage accuracy in the power spectrum up to k ˜ 0.4 h Mpc-1 (within 5 per cent up to k ˜ 0.6 h Mpc-1) with accurate bispectra improving previous results based on Lagrangian perturbation theory.
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