The Outer Structure of Galactic Disks: Connections Between Bars, Disks, and Environments

Surface-brightness profiles for early-type (S0-Sb) disks exhibit three main classes (Type I, II, and III). Type II profiles are more common in barred galaxies, and most of the time appear to be related to the bar’s Outer Lindblad Resonance. Roughly half of barred galaxies in the field have Type II profiles, but almost none in the Virgo Cluster do; this might be related to ram-pressure stripping in clusters. A strong $\mathit{\text{anti}}$correlation is found between Type III profiles (“antitruncations”) and bars: Type III profiles are most common when there is no bar, and least common when there is a strong bar.