Weak-lensing peaks in simulated light cones: Investigating the coupling between dark matter and dark energy

In this paper, we study the statistical properties of weak-lensing peaks in light cones generated from cosmological simulations. In order to assess the prospects of such observable as a cosmological probe, we consider simulations that include interacting Dark Energy (hereafter DE) models with coupling term between DE and Dark Matter. Cosmological models that produce a larger population of massive clusters have more numerous high signal-to-noise peaks; among models with comparable numbers of clusters those with more concentrated haloes produce more peaks. The most extreme model under investigation shows a difference in peak counts of about 20 per cent with respect to the reference Λ cold dark matter model. We find that peak statistics can be used to distinguish a coupling DE model from a reference one with the same power spectrum normalization. The differences in the expansion history and the growth rate of structure formation are reflected in their halo counts, non-linear scale features and, through them, in the properties of the lensing peaks. For a source redshift distribution consistent with the expectations of future space-based wide field surveys, we find that typically 70 per cent of the cluster population contributes to weak-lensing peaks with signal-to-noise ratios larger than 2, and that the fraction of clusters in peaks approaches 100 per cent for haloes with redshift z ≰ 0.5. Our analysis demonstrates that peak statistics are an important tool for disentangling DE models by accurately tracing the structure formation processes as a function of the cosmic time.