Non-Gaussian morphology on large scales: Minkowski functionals of the REFLEX cluster catalogue

In order to quantify higher{order correlations of the galaxy cluster distribution we use a complete family of additive measures which give scale{dependent morphological information. Minkowski functionals can be expressed analytically in terms of integrals of n{point correlation functions. They can be compared with measured Minkowski functionals of volume limited samples extracted from the Reflex survey. We nd signicant non{Gaussian features in the large{scale spatial distribution of galaxy clusters. A Gauss{Poisson process can be excluded as a viable model for the distribution of galaxy clusters at the signicance level of 95%.