Numerical investigation into the generation of spiral density waves by bars in rigidly rotating disks

Abstract

A numerical study of the large-scale structure of a spiral galaxy is presented. The study involves the examination of the nonstationary response in a rigidly rotating gas disk to the potential of a bar. When the angular velocity of the bar exceeds the angular velocity of the disk, a quasi-stationary two-arm trailing spiral pattern, which rotates with the angular velocity of the bar, is generated. When the angular velocity of the disk exceeds that of the bar, there is no spiral pattern. Calculations confirm that the bars existing in the central regions of disk galaxies are capable of generating sustaining two-arm spiral patterns.