Dynamical Stability and Environmental Influences in Low Surface Brightness Disk Galaxies

Using analytic stability criteria, we demonstrate that, due to their lowsurface mass density and large dark matter content, LSB disks are quite stableagainst the growth of global nonaxisymmetric modes such as bars. However,depending on their (poorly constrained) stellar velocity dispersions, they maybe only marginally stable against local instabilities. We simulate a collisionbetween an LSB and HSB galaxy and find that, while the HSB galaxy forms astrong bar, the response of the LSB disk is milder, manifesting weaker ringsand spiral features. The lack of sufficient disk self-gravity to amplifydynamical instabilities naturally explains the rarity of bars in LSB disks. Thestability of LSB disks may also inhibit interaction-driven gas inflow andstarburst activity in these galaxies.