Testing the reliability of weak lensing cluster detections

We study the reliability of dark-matter halo detections with three different linear filters applied to weak-lensing data. We use raytracing in the multiple lens-plane approximation through a large cosmological simulation to construct realizations of cosmic lensing by large-scale structures between redshifts zero and two. We apply the filters mentioned above to detect peaks in the weak-lensing signal and compare them with the true population of dark matter halos present in the simulation. We confirm the stability and performance of a filter optimised for suppressing the contamination by large-scale structure. It allows the reliable detection of dark-matter halos with masses above a few times 1013 h-1 M⊙ with a fraction of spurious detections below ∼10%. For sources at redshift two, 50% of the halos more massive than ∼7 × 1013 h-1 M⊙ are detected, and completeness is reached at ∼2 × 1014 h-11 M⊙ © ESO 2007.