UNC-CH Physics and Astronomy Masters Defense

John Dupuy

“Mass inflow in barred spiral galaxies”

We seek to explore the effects of mass inflow on barred spiral galaxies. We use a logarithmically spaced cylindrical grid to simulate gas flow in a barred galaxy gravitational potential. We then investigate the effect of gas accretion from an intermediate or high- velocity cloud onto the disk of this barred spiral galaxy for a large variety of inflow parameters. We provide estimates on the timescales of these inflow events by computing the asymmetry/lopsidedness parameter (A1) in the gas density for each simulation. For parameters explored, mass inflow can have a lasting impact on A1. This suggests that lopsidedness arising from gas infall is observable. In some cases, the inflow material is quickly swept up by orbiting gas and can lead to the formation of lanes in the galactic disk. Depending on initial position and mass, the inflow material can also enhance density at the cusps of the bar where gas transfers between orbit families. Our models provide a possible explanation for lopsidedness observed in isolated galaxies with no near companion.