Enhancing the Cosmic Shear Power Spectrum

Abstract

Applying a transformation to a non-Gaussian field can enhance the information content of the resulting power spectrum, by reducing the correlations between Fourier modes. In the context of weak gravitational lensing, it has been shown that this gain in information content is significantly compromised by the presence of shape noise. We apply clipping to mock convergence fields, a technique which is known to be robust in the presence of noise and has been successfully applied to galaxy number density fields. When analysed in isolation the resulting convergence power spectrum returns degraded constraints on cosmological parameters. However substantial gains can be achieved by performing a combined analysis of the power spectra derived from both the original and transformed fields. Even in the presence of realistic levels of shape noise, we demonstrate that this approach is capable of reducing the area of likelihood contours within the ${\Omega }_m-{\sigma }_8$ plane by more than a factor of three.

8 pages, 3 figures; v2 now includes full likelihood analysis. Accepted for publication in MNRAS

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• k-cut Cosmic Shear: Tunable Power Spectrum Sensitivity to Test Gravity
• KiDS-450: Enhancing cosmic shear with clipping transformations
• A Bayesian method for combining theoretical and simulated covariance matrices for large-scale structure surveys
• The Information Content of Projected Galaxy Fields
• Hybrid summary statistics: neural weak lensing inference beyond the power spectrum
• Neural style transfer of weak lensing mass maps