Abstract
Today's galaxies have regular, symmetrical morphologies, " spirals " or " ellipticals ". The latest generations of telescopes have shown that primordial galaxies in the distant, young Universe have very different, irregular shapes, most often fragmented into a few large pieces. What are these mysterious pieces, small galaxies in the process of assembling and merging to form more massive galaxies, or traces of fragmentation of already massive galaxies ? According to numerical simulations, both mechanisms can occur in the Universe, and could be at the origin of the diversity of current galaxy morphologies in the " Hubble sequence ".
