Bar formation in disk galaxies

These bars are thought to form either through a physical process inherent in galaxies, or through an external process such as galaxy-galaxy interactions. However, there are other plausible mechanisms of bar formation that still need to be observationally tested.

Here we present the observational evidence that bars can form via cluster-cluster interaction. We examined 105 galaxy clusters at redshift 0.015<z<0.060 that are selected from the Sloan Digital Sky Survey data, and identified 16 interacting clusters. We find that the barred disk-dominated galaxy fraction is about 1.5 times higher in interacting clusters than in clusters with no clear signs of ongoing interaction (42% versus 27%).