Localizing Transformations of the Galaxy-Galaxy Lensing Observable

Understand

Modern cosmological analyses of galaxy-galaxy lensing face a theoretical systematic effect arising from the non-locality of the observed galaxy-galaxy lensing signal.

• Because the predicted tangential shear signal at a given separation depends on the physical modeling on all scales internal to that separation, systematic uncertainties in the modeling of non-linear small scales are propagated outwards to larger scales.
• Even in the absence of other limiting factors, this systematic effect alone can necessitate conservative small-scale cuts, resulting in significant losses of information in the tangential shear data vector.
• We construct a simple linear transformation of the observable that removes this non-locality, enabling more aggressive small-scale cuts for a given theoretical model.