Minimising the impact of scale-dependent galaxy bias on the joint cosmological analysis of large scale structures

Abstract

We present a mitigation strategy to reduce the impact of non-linear galaxy bias on the joint `$3\times 2$pt' cosmological analysis of weak lensing and galaxy surveys. The $\Psi$-statistics that we adopt are based on Complete Orthogonal Sets of E/B Integrals (COSEBIs). As such they are designed to minimise the contributions to the observable from the smallest physical scales where models are highly uncertain. We demonstrate that $\Psi$-statistics carry the same constraining power as the standard two-point galaxy clustering and galaxy-galaxy lensing statistics, but are significantly less sensitive to scale-dependent galaxy bias. Using two galaxy bias models, motivated by halo-model fits to data and simulations, we quantify the error in a standard $3\times 2$pt analysis where constant galaxy bias is assumed. Even when adopting conservative angular scale cuts, that degrade the overall cosmological parameter constraints, we find of order $1\sigma$ biases for Stage III surveys on the cosmological parameter $S_8={\sigma }_8({\Omega }_{\mathrm{m}}/0.3{)}^{\alpha }$. This arises from a leakage of the smallest physical scales to all angular scales in the standard two-point correlation functions. In contrast, when analysing $\Psi$-statistics under the same approximation of constant galaxy bias, we show that the bias on the recovered value for $S_8$ can be decreased by a factor of $\sim 2$, with less conservative scale cuts. Given the challenges in determining accurate galaxy bias models in the highly non-linear regime, we argue that $3\times 2$pt analyses should move towards new statistics that are less sensitive to the smallest physical scales.

14 pages, 13 figures, accepted to be published in MNRAS

References in corpus (13)

• Extended Limber Approximation
• The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: Anisotropic galaxy clustering in Fourier-space
• The fourth data release of the Kilo-Degree Survey: ugri imaging and nine-band optical-IR photometry over 1000 square degrees
• Gravity and Large-Scale Non-local Bias
• KiDS-450 + 2dFLenS: Cosmological parameter constraints from weak gravitational lensing tomography and overlapping redshift-space galaxy clustering
• The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: cosmological implications of the configuration-space clustering wedges
• KiDS-450: The tomographic weak lensing power spectrum and constraints on cosmological parameters
• Cosmological Parameters and Neutrino Masses from the Final Planck and Full-Shape BOSS Data
• KiDS+VIKING-450 and DES-Y1 combined: Mitigating baryon feedback uncertainty with COSEBIs
• The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: Cosmological implications of the Fourier space wedges of the final sample
• Probing dark energy with the shear-ratio geometric test
• The 2-degree Field Lensing Survey: design and clustering measurements
• Scale Dependent Galaxy Bias in the SDSS as a function of Luminosity and Colour

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• Organised Randoms: Learning and correcting for systematic galaxy clustering patterns in KiDS using self-organising maps
• Consistency of cosmic shear analyses in harmonic and real space
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• KiDS-Legacy: Covariance validation and the unified OneCovariance framework for projected large-scale structure observables
• Dark Energy Survey Year 3 Results: Constraints on cosmological parameters and galaxy bias models from galaxy clustering and galaxy-galaxy lensing using the redMaGiC sample
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