Present-day astronomers are certain that many existing galaxies are products of repeated encounters among smaller ones that merge after the collision. But older theoretical studies have suggested that the galaxy resulting from a merger of two similarly sized galaxies would be uniformly elliptical in shape. Although this does apply to some galaxies, our own Milky Way and most others exhibit a very different configuration: 70% of them have a disk-shaped region.
To confirm whether galaxy mergers can also produce disk galaxies, an international group led by astronomer Junko Ueda from the Japanese Society for the Promotion of Science analyzed images of final-stage galaxy mergers captured by a network of radio telescopes operating worldwide in coordination with the ALMA observatory in Chile. The team successfully mapped the shape and speed of gas clouds in the galaxies that emerged from these collisions. The data published in August 2014 in The Astrophysical Journal Supplement revealed that 24 of the 30 galaxies studied contain a rotating disk-shaped region of gas, similarly to those found in disk galaxies.Republish