Impact of survey geometry and super-sample covariance on future photometric galaxy surveys

Abstract

Photometric galaxy surveys probe the late-time Universe where the density field is highly non-Gaussian. A consequence is the emergence of the super-sample covariance (SSC), a non-Gaussian covariance term that is sensitive to fluctuations on scales larger than the survey window. In this work, we study the impact of the survey geometry on the SSC and, subsequently, on cosmological parameter inference. We devise a fast SSC approximation that accounts for the survey geometry and compare its performance to the common approximation of rescaling the results by the fraction of the sky covered by the survey, $f_{\mathrm{SKY}}$, dubbed 'full-sky approximation'. To gauge the impact of our new SSC recipe, dubbed 'partial-sky', we perform Fisher forecasts on the parameters of the $(w_0,w_a)$-CDM model in a 3x2 points analysis, varying the survey area, the geometry of the mask and the galaxy distribution inside our redshift bins. The differences in the marginalised forecast errors, with the full-sky approximation performing poorly for small survey areas but excellently for stage-IV-like areas, are found to be absorbed by the marginalisation on galaxy bias nuisance parameters. For large survey areas, the unmarginalised errors are underestimated by about 10% for all probes considered. This is a hint that, even for stage-IV-like surveys, the partial-sky method introduced in this work will be necessary if tight priors are applied on these nuisance parameters.

arXiv comment12 pages, 11 figures, 2 tables, 2 appendices. Published version in A&A

References in corpus (48)

• Astropy: A Community Python Package for Astronomy
• HEALPix -- a Framework for High Resolution Discretization, and Fast Analysis of Data Distributed on the Sphere
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• Accelerating Universes with Scaling Dark Matter
• The Cosmic Linear Anisotropy Solving System (CLASS) II: Approximation schemes
• The DESI Experiment Part I: Science,Targeting, and Survey Design
• Dark Energy Survey Year 3 Results: Cosmological Constraints from Galaxy Clustering and Weak Lensing
• Euclid Definition Study Report
• LSST Science Book, Version 2.0
• Large-Scale Galaxy Bias
• Cosmic Growth History and Expansion History
• KiDS-1000 Cosmology: Multi-probe weak gravitational lensing and spectroscopic galaxy clustering constraints
• MASTER of the CMB Anisotropy Power Spectrum: A Fast Method for Statistical Analysis of Large and Complex CMB Data Sets
• Dark energy constraints from cosmic shear power spectra: impact of intrinsic alignments on photometric redshift requirements
• Sample Variance Considerations for Cluster Surveys
• A Parameterized Post-Friedmann Framework for Modified Gravity
• CosmoSIS: modular cosmological parameter estimation
• Intrinsic galaxy alignments from the 2SLAQ and SDSS surveys: luminosity and redshift scalings and implications for weak lensing surveys
• Power Spectrum Super-Sample Covariance
• CosmoLike - Cosmological Likelihood Analyses for Photometric Galaxy Surveys
• Myths and Truths Concerning Estimation of Power Spectra
• The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: cosmological implications of the configuration-space clustering wedges
• Precision calculations of the cosmic shear power spectrum projection
• Dark Energy Survey Year 1 Results: Multi-Probe Methodology and Simulated Likelihood Analyses
• Galaxy Power Spectrum Multipoles Covariance in Perturbation Theory
• Cosmological constraints from BOSS with analytic covariance matrices
• Dark Energy Survey Year 3 Results: Covariance Modelling and its Impact on Parameter Estimation and Quality of Fit
• The Limits of Cosmic Shear
• Accurate cosmic shear errors: do we need ensembles of simulations?
• Complete super-sample lensing covariance in the response approach
• Photometric Redshift Requirements for Self-Calibration of Cluster Dark Energy Studies
• Joint analysis of cluster number counts and weak lensing power spectrum to correct for the super-sample covariance
• Galaxy power-spectrum responses and redshift-space super-sample effect
• Bispectrum Supersample Covariance
• Testing the Cosmic Shear Spatially-Flat Universe Approximation with Generalized Lensing and Shear Spectra
• Combining cluster number counts and galaxy clustering
• Super-sample covariance approximations and partial sky coverage
• Angpow: a software for the fast computation of accurate tomographic power spectra
• A Robust Measure of Cosmic Structure beyond the Power-Spectrum: Cosmic Filaments and the Temperature of Dark Matter
• Fast and easy super-sample covariance of large scale structure observables
• Euclid: The reduced shear approximation and magnification bias for Stage IV cosmic shear experiments
• Information escaping the correlation hierarchy of the convergence field in the study of cosmological parameters
• Non-Gaussianity in the Weak Lensing Correlation Function Likelihood -- Implications for Cosmological Parameter Biases
• Covariance of the galaxy angular power spectrum with the halo model
• An optimal survey geometry of weak lensing survey: minimizing super-sample covariance
• Inadequacy of internal covariance estimation for super-sample covariance
• Sufficiency of a Gaussian power spectrum likelihood for accurate cosmology from upcoming weak lensing surveys
• The impact of braiding covariance and in-survey covariance on next-generation galaxy surveys

Cited by in corpus (12)

• Euclid. I. Overview of the Euclid mission
• CosmoGridV1: a simulated $w$CDM theory prediction for map-level cosmological inference
• Super-sample covariance of the power spectrum, bispectrum, halos, voids, and their cross covariances
• Euclid: Covariance of weak lensing pseudo-$C_{\ell }$ estimates. Calculation, comparison to simulations, and dependence on survey geometry
• Testing the accuracy of likelihoods for cluster abundance cosmology
• Euclid preparation. LII. Forecast impact of super-sample covariance on 3x2pt analysis with Euclid
• Efficient computation of the super-sample covariance for stage IV galaxy surveys
• What is the super-sample covariance? A fresh perspective for second-order shear statistics
• Cosmological inference including massive neutrinos from the matter power spectrum: biases induced by uncertainties in the covariance matrix
• Improving CMB constraints on early Universe physics with LSS: A multi-probe forecast including cross-covariance
• Super sample covariance and the volume scaling of galaxy survey covariance matrices
• Towards including super-sample covariance in the unbinned likelihood for cluster abundance cosmology