DESI mock challenge: constructing DESI galaxy catalogues based on FastPM simulations

Variu, Andrei; Alam, Shadab; Zhao, Cheng; Chuang, Chia-Hsun; Yu, Yu; Forero-Sánchez, Daniel; Ding, Zhejie; Kneib, Jean-Paul; Aguilar, Jessica Nicole; Ahlen, Steven; Brooks, David; Claybaugh, Todd; Cole, Shaun; Dawson, Kyle; de la Macorra, Axel; Doel, Peter; Forero-Romero, Jaime E; Gontcho, Satya Gontcho A; Honscheid, Klaus; Landriau, Martin; Manera, Marc; Miquel, Ramon; Nie, Jundan; Percival, Will; Poppett, Claire; Rezaie, Mehdi; Rossi, Graziano; Sanchez, Eusebio; Schubnell, Michael; Seo, Hee-Jong; Tarlé, Gregory; Magana, Mariana Vargas; Zhou, Zhimin

Abstract

Together with larger spectroscopic surveys such as the Dark Energy Spectroscopic Instrument (DESI), the precision of large scale structure studies and thus the constraints on the cosmological parameters are rapidly improving. Therefore, one must build
realistic simulations and robust covariance matrices. We build galaxy catalogues by applying a halo occupation distribution
(HOD) model upon the FASTPM simulations, such that the resulting galaxy clustering reproduces high-resolution N-body
simulations. While the resolution and halo finder are different from the reference simulations, we reproduce the reference galaxy
two-point clustering measurements – monopole and quadrupole – to a precision required by the DESI Year 1 emission line galaxy
sample down to non-linear scales, i.e. k < 0.5 h Mpc−1 or s > 10 Mpc h−1. Furthermore, we compute covariance matrices based
on the resulting FASTPM galaxy clustering – monopole and quadrupole. We study for the first time the effect of fitting on Fourier
conjugate (e.g. power spectrum) on the covariance matrix of the Fourier counterpart (e.g. correlation function). We estimate the
uncertainties of the two parameters of a simple clustering model and observe a maximum variation of 20 per cent for the different
covariance matrices. Nevertheless, for most studied scales the scatter is between 2 and 10 per cent. Consequently, using the
current pipeline we can precisely reproduce the clustering of N-body simulations and the resulting covariance matrices provide
robust uncertainty estimations against HOD fitting scenarios. We expect our methodology will be useful for the coming DESI
data analyses and their extension for other studies.

Citation

Variu, A., Alam, S., Zhao, C., Chuang, C., Yu, Y., Forero-Sánchez, D., …Zhou, Z. (2024). DESI mock challenge: constructing DESI galaxy catalogues based on FastPM simulations. Monthly Notices of the Royal Astronomical Society, 527(4), 11539-11558. https://doi.org/10.1093/mnras/stad3742

• Journal Article Type: Article
• Acceptance Date: Nov 14, 2023
• Online Publication Date: Dec 4, 2023
• Publication Date: 2024-02
• Deposit Date: Mar 18, 2024
• Publicly Available Date: Mar 18, 2024
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 527
• Issue: 4
• Pages: 11539-11558
• DOI: https://doi.org/10.1093/mnras/stad3742
• Keywords: Space and Planetary Science; Astronomy and Astrophysics
• Public URL: https://durham-repository.worktribe.com/output/2331700