Multicolor optical imaging of powerful far-infrared galaxies - more evidence for a link between galaxy mergers and far-infrared emission

Broadband optical (B and R) imaging results are presented for a sample of 39 powerful far-infrared galaxies detected by IRAS. The imaging program has revealed that (1) at least 70 percent of the galaxies have very distorted optical morphologies (much larger than the value 14 percent obtained for a control sample of averarage galaxies); (2) there is an unusually low occurrence of apparently flattened members of the sample compared to either an optical- or infrared-selected sample of spiral galaxies; (3) the galaxies are moderately luminous in the optical; and (4) the galaxy colors most closely resemble Sb or Sbc galaxies seen at the appropriate redshift. These results demonstrate that the optical properties of NGC 6240 and Arp 220 are typical of powerful far-infrared galaxies, and add to the impressive body of evidence linking the collision/merger of disk galaxies to the production of intense infrared emission. 27 references.