Testing quadratic maximum likelihood estimators for forthcoming Stage-IV weak lensing surveys

Headline constraints on cosmological parameters from current weak lensing surveys are derived two-point statistics that known to be statistically sub-optimal, even in the case of Gaussian fields. We study performance a new fast implementation Quadratic Maximum Likelihood (QML) estimator, optimal for fields, test Pseudo-Cl estimators upcoming and quantify gain more method. Through use realistic survey geometries, noise levels, power spectra, we find there is decrease errors recovered E-mode spectra level ~20% when using QML estimator over largest angular scales, while significant decreases associated with B-modes estimator. This raises prospects being able constrain physics through enhanced sensitivity forthcoming our provides. method uses conjugate-gradient finite-differences differentiation methods resulting most efficient full-sky yet, allowing us process maps at resolutions prohibitively expensive existing codes. In addition, investigate effects apodisation, B-mode purification, non-Gaussian statistical properties estimators. Our publicly available can accessed GitHub.