Angular complexity in strong lens substructure detection

Understand

Strong gravitational lensing can be used to find otherwise invisible dark matter subhaloes.

• In such an analysis, the lens galaxy mass model is a significant source of systematic uncertainty.
• In this paper we analyse the effect of angular complexity in the lens model.
• We use multipole perturbations which introduce low-order deviations from pure ellipticity in the isodensity contours, keeping the radial density profile fixed.