Shock-induced star cluster formation in colliding galaxies

We studied the formation process of star clusters using high-resolution N-body/ smoothed particle hydrodynamics simulations of colliding galaxies. The total number of particles is 1.2 × 108 for our high resolution run. The gravitational softening is 5 pc and we allow gas to cool down to ∼ 10 K. During the first encounter of the collision, a giant filament consists of cold and dense gas found between the progenitors by shock compression. A vigorous starburst took place in the filament, resulting in the formation of star clusters. The mass of these star clusters ranges from 105−8 M_. These star clusters formed hierarchically: at first small star clusters formed, and then they merged via gravity, resulting in larger star clusters.