Tuesday

The considerable discrepancy between the cosmological constraints obtained from weak gravitational lensing and the CMB is the source of much debate. With all apparent systematics accounted for on both sides, this tension implies that our fundamental theory of cosmic expansion needs revisiting. Tighter constraints on cosmological parameters are essential for confirming whether this tension is indicative of new physics.

In answer to this riddle, I showcase cosmic shear correlation functions obtained under “clipping” transformations – powerful but previously infeasible weak lensing probes of cosmology. Clipping partially eliminates the contaminating signals from regions of non-linear gravitational collapse. This has the potential for significantly improving constraints on the mass energy density and the variance of matter-density fluctuations in the universe. I calibrate these statistics with the cutting-edge Mira Titan N-body simulations, and present the results of applying this framework to the first 450 square degrees of deep multi-band imaging from the Kilo-Degree Survey (KiDS).