x-cut Cosmic Shear: Optimally Removing Sensitivity to Baryonic and Nonlinear Physics with an Application to the Dark Energy Survey Year 1 Shear Data

Abstract

We present a new method, called $x$-cut cosmic shear, which optimally removes sensitivity to poorly modeled scales from the two-point cosmic shear signal. We show that the $x$-cut cosmic shear covariance matrix can be computed from the correlation function covariance matrix in a few minutes, enabling a likelihood analysis at virtually no additional computational cost. Further we show how to generalize $x$-cut cosmic shear to galaxy-galaxy lensing. Performing an $x$-cut cosmic shear analysis of the Dark Energy Survey Year 1 (DESY1) shear data, we reduce the error on $S_8={\sigma }_8({\Omega }_m/0.3{)}^{0.5}$ by $32\%$ relative to a correlation function analysis with the same priors and angular scale cut criterion, while showing our constraints are robust to different baryonic feedback models. Largely driven by information at small angular scales, our result, $S_8=0.734\pm 0.026$, yields a $2.6\sigma$ tension with the Planck Legacy analysis of the cosmic microwave background. As well as alleviating baryonic modelling uncertainties, our method can be used to optimally constrain a large number of theories of modified gravity where computational limitations make it infeasible to model the power spectrum down to extremely small scales. The key parts of our code are made publicly available.

18 pages. 10 Figures. PRD Accepted

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• Constraining $f(R)$ Gravity with a $k$-cut Cosmic Shear Analysis of the Hyper Suprime-Cam First-Year Data
• Cosmological feedback from a halo assembly perspective
• Numerical complexity of the joint nulled weak-lensing probability distribution function
• Cosmological gravity on all scales IV: 3x2pt Fisher forecasts for pixelised phenomenological modified gravity
• Principal Components for Model-Agnostic Modified Gravity with 3x2pt
• The RSD Sorting Hat: Unmixing Radial Scales in Projection
• Cosmic shear nulling as a geometrical cosmological probe: Methodology and sensitivity to cosmological parameters and systematics
• Euclid: Forecasts for $k$-cut $3\times 2$ Point Statistics
• The Covariance of Photometric and Spectroscopic Two-Point Statistics: Implications for Cosmological Parameter Inference
• Cosmological gravity on all scales V: MCMC forecasts combining large scale structure and CMB lensing for binned phenomenological modified gravity