Description
A survey-window free estimator of cosmic shear bispectrum
The distortion of galaxy shapes caused by weak gravitational lensing due to foreground large-scale structures is a powerful tool for probing the spatial distribution of dark matter and the evolution of structure formation. Cosmic shear encodes information about the matter distribution in both the linear and nonlinear regimes. In this context, commonly used two-point statistics are not sufficient, and higher-order statistics are needed to fully capture the available information. The lowest-order higher-statistics is the bispectrum, the Fourier-transformed counterpart of the three-point correlation function. Therefore, utilizing the cosmic shear bispectrum enables to obtain tighter constraints on cosmological parameters, and also enables to investigate the parity violation in our universe and unknown systematics.
However, straightforward Fourier analyses of survey data suffer from complications introduced by complex survey geometries and masked regions (e.g., due to bright stars). These effects mix Fourier modes, preventing a clean separation of the E/B modes and complicating the theoretical interpretation of the measured bispectrum. We have developed a new method to estimate the cosmic shear bispectrum that is free from the survey window effects, extending the maximum likelihood method, used in CMB and galaxy clustering analyses, to cosmic shear.
