Dynamical Stability and Environmental Influences in Low Surface Brightness Disk Galaxies.pdfVIP

To appear in the Astrophysical Journal Letters Dynamical Stability and Environmental Influences in Low Surface Brightness Disk Galaxies 1,2 3 4 6 J. Christopher Mihos, Stacy S. McGaugh , and W.J.G. de Blok 9 9 1 ABSTRACT c e D Using analytic stability criteria, we demonstrate that, due to their low 1 1 surface mass density and large dark matter content, LSB disks are quite stable against the growth of global nonaxisymmetric modes such as bars. However, 1 v depending on their (poorly constrained) stellar velocity dispersions, they may 5 1 be only marginally stable against local instabilities. We simulate a collision 1 between an LSB and HSB galaxy and find that, while the HSB galaxy forms 2 1 a strong bar, the response of the LSB disk is milder, manifesting weaker rings 6 and spiral features. The lack of sufficient disk self-gravity to amplify dynamical 9 / instabilities naturally explains the rarity of bars in LSB disks. The stability of h p LSB disks may also inhibit interaction-driven gas inflow and starburst activity - o in these galaxies. r t s a : v Subject headings: galaxies:evolution, galaxies:interactions, galaxies:kinematics i X and dynamics, galaxies:spiral, galaxies:starburst, galaxies:structure r a 1Hubble Fellow 2Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218; hos@pha.jhu.edu 3Carnegie Institute of Washington, Department of Terrestrial