Shear and magnification angular power spectra and higher-order moments from weak gravitational lensing

We present new results on the gravitational lensing shear and magnification power spectra obtained from numerical simulations of a flat cosmology with a cosmological constant. These results are of considerable interest since both the shear and the magnification are observables. We find that the power spectrum in the convergence behaves as expected, but the magnification develops a shot-noise spectrum due to the effects of discrete, massive clusters and symptomatic of moderate lensing beyond the weak-lensing regime. We find that this behaviour can be suppressed by 'clipping' of the largest projected clusters. Our results are compared with predictions from a halo-model-inspired functional fit for the non-linear evolution of the matter field and show excellent agreement. We also study the higher-order moments of the convergence field and find a new scaling relationship with redshift. In particular, the statistic S-3 is found to vary as s(z)(-2.00 +/- 0.08) (where z(s) is the source redshift) for the cosmology studied, which makes corrections for different median redshifts in different observational surveys particularly simple to apply.