Measuring primordial non-Gaussianity through weak-lensing peak counts

We explore the possibility of detecting primordial non-Gaussianity of the local type using weak-lensing peak counts. We measure the peak abundance in sets of simulated weak-lensing maps corresponding to three models fnl = 0, -100, and 100. Using survey specifications similar to those of euclid and without assuming any knowledge of the lens and source redshifts, we find the peak functions of the non-Gaussian models with fnl = ±100 to differ by up to 15% from the Gaussian peak function at the high-mass end. For the assumed survey parameters, the probability of fitting an fnl = 0 peak function to the fnl = ±100 peak functions is less than 0.1%. Assuming the other cosmological parameters are known, fnl can be measured with an error Δ fnl ≈ 13. It is therefore possible that future weak-lensing surveys like euclid and lsst may detect primordial non-Gaussianity from the abundance of peak counts, and provide information complementary to that obtained from the cosmic microwave background.