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Mitigating the noise of DESI mocks using analytic control variates

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arxiv 2308.12343 v2 pith:PSETA4VV submitted 2023-08-23 astro-ph.CO

Mitigating the noise of DESI mocks using analytic control variates

classification astro-ph.CO
keywords controlanalyticgalaxymeasurementspowervariancevariatesanalysis
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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In order to address fundamental questions related to the expansion history of the Universe and its primordial nature with the next generation of galaxy experiments, we need to model reliably large-scale structure observables such as the correlation function and the power spectrum. Cosmological $N$-body simulations provide a reference through which we can test our models, but their output suffers from sample variance on large scales. Fortunately, this is the regime where accurate analytic approximations exist. To reduce the variance, which is key to making optimal use of these simulations, we can leverage the accuracy and precision of such analytic descriptions using Control Variates (CV). The power of control variates stems from utilizing inexpensive but highly correlated surrogates of the statistics one wishes to measure. The stronger the correlation between the surrogate and the statistic of interest, the larger the variance reduction delivered by the method. We apply two control variate formulations to mock catalogs generated in anticipation of upcoming data from the Dark Energy Spectroscopic Instrument (DESI) to test the robustness of its analysis pipeline. Our CV-reduced measurements offer a factor of 5-10 improvement in the measurement error compared with the raw measurements. We explore the relevant properties of the galaxy samples that dictate this reduction and comment on the improvements we find on some of the derived quantities relevant to Baryon Acoustic Oscillation (BAO) analysis. We also provide an optimized package for computing the power spectra and other two-point statistics of an arbitrary galaxy catalog as well as a pipeline for obtaining CV-reduced measurements on any of the AbacusSummit cubic box outputs. We make our scripts publicly available and report a speed improvement of $\sim$10 for a grid size of $N_{\rm mesh} = 256^3$ compared with \texttt{nbodykit}.

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Forward citations

Cited by 7 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Fewer simulations, sharper covariances: Reducing mock covariance noise with Zeldovich approximation control variates

    astro-ph.CO 2026-05 unverdicted novelty 7.0

    Control variates with Zeldovich mocks reduce covariance matrix variance by up to an order of magnitude on large scales in DESI-like mocks.

  2. Density reconstruction from biased tracers: Testing the equivalence principle through consistency relations

    astro-ph.CO 2025-10 conditional novelty 7.0

    An anti-symmetric 'shift' response in the clustering of two galaxy populations carries a 1/K equivalence-principle-violation signal, and a fast quadratic estimator can extract it at the same projected sensitivity as t...

  3. DESI 2024 III: Baryon Acoustic Oscillations from Galaxies and Quasars

    astro-ph.CO 2024-04 accept novelty 7.0

    DESI measures BAO scales in six redshift bins with 0.52% combined precision using 5.7 million objects, detecting the signal at up to 9.1 sigma and finding larger scales than Planck LCDM at z<0.8.

  4. Lyman-Alpha Forest and its Cross-Correlation with High-Redshift Galaxies in Effective Field Theory at the Field Level

    astro-ph.CO 2026-06 unverdicted novelty 6.0

    An EFT-based field-level forward model for the Lyman-alpha forest matches simulations at the percent level on quasi-linear scales and generates mocks for DESI and DESI-II analyses.

  5. The 3D clustering of Lyman Alpha Emitters measured with DESI

    astro-ph.CO 2026-06 unverdicted novelty 6.0

    DESI LAE clustering measurements give a linear bias of 2.31-2.62 with constraints on radiative transfer effects and halo occupation from correlation functions and power spectra.

  6. Faster CMB lensing with control variates

    astro-ph.CO 2026-05 unverdicted novelty 6.0

    A control variate technique using differenced estimates from realistic masked and isotropic simulations reduces the computational cost of CMB lensing bias calculations by a factor of three to five.

  7. Simulation budgeting for hybrid effective field theories

    astro-ph.CO 2025-10 unverdicted novelty 4.0

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