2006MNRAS.372..279D

During the late stages of galaxy mergers or galactic interactions, supergiant molecular cloud complexes are turned into large numbers of stellar superclusters. Supergiant molecular cloud complexes show fractal structure due to turbulence and/or self-gravitation; therefore, superclusters formed out of these complexes are expected to exhibit similar geometry. Here we study the evolution of the multifractal pattern of the projected spatial distribution of supergiant molecular cloud complexes in the Antennae (NGC 4038/4039) as they turn into superclusters during the sustained starburst event. Using two data sets of the positions of supergiant molecular clouds and of stellar superclusters, the fractal spectrum is determined using the Minkowski-sausage method to calculate the Minkowski-Bouligand dimension as a function of the parameter q. For clouds, this measure varies with q in the range 0.7-2.2 for q in the interval [-4, 4]. For the projected distribution of superstar clusters it varies with q in the range 1.15-1.71. For the overlap region in the Antennae, the average projected fractal dimension of supergiant clouds is found to be 1.3 and the average fractal dimension of superclusters is 1.6. Our results indicate that during star formation the local fractal dimension increases, likely due to diffusion-like evolution.