Measuring primordial non-Gaussianity through weak lensing peak counts

TL;DR

This paper investigates how future weak lensing surveys can detect primordial non-Gaussianity by analyzing peak counts, showing potential for measuring f_NL with reasonable accuracy and complementing CMB data.

Contribution

It demonstrates that weak lensing peak counts can distinguish between Gaussian and non-Gaussian models, providing a new method to measure primordial non-Gaussianity.

Findings

Peak functions differ by up to 15% for f_NL=±100 at high masses.

The probability of misidentifying non-Gaussianity is less than 0.1%.

f_NL can be measured with an error of about 13 using future surveys.

Abstract

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 f_NL={0, +100, -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 f_NL=+-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 f_NL=0 peak function to the f_NL=+-100 peak functions is less than 0.1%. Assuming the other cosmological parameters known, f_NL can be measured with an error \Delta f_NL ~ 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 complementary information to that obtained from the cosmic microwave background.