The topology of a weak lensing field in the neighborhood of MS 1054-03

We report the first measurement of genus curves for the two-dimensional mass map in the neighborhood of the rich X-ray-luminous galaxy cluster MS 1054-03 at z = 0.83, reconstructed from weak lensing data obtained by Suprime-Cam on the prime focus of the 8.2 m Subaru Telescope. We find that the genus curve measured in the whole survey field deviates from that expected from a random Gaussian field. We show that this non-Gaussianity is induced by the rich cluster in this region and that the genus curve for the region without the cluster is consistent with the prediction for a random Gaussian field. The results demonstrate the feasibility of the genus statistics to examine the non-Gaussianity due to the large-scale structures and to probe the statistical properties of the large-scale clustering.