Crash-bang birth of spiral galaxies

摘要

Spiral galaxies may have emerged from a more cataclysmic past than expected. New simulations suggest they grew their spiral arms after being mashed up in vast collisions. A group led by Francois Hammer of the Paris Observatory in Meudon, France, compared a sample of relatively local spiral galaxies with distant galaxies that appear to us as they were 6 billion years ago. Far fewer tidy spirals existed in the ancient era, and far more galaxies boasted peculiar, unclassifiable shapes. Those oddly shaped galaxies must develop into spirals to explain the distribution of galactic shapes we see today.