Formation of Plumes in Head‐on Collisions of Galaxies

Using N-body and SPH modeling we perform 3D numerical simulations of head-oncollisions between gas rich disk galaxies, including collisions betweencounter-rotating disks and off-center collisions. Pure stellar intruders do notproduce gaseous plumes similar to those seen in the Cartwheel and VII Zw466complexes of interacting galaxies; the presence of gas in an intruder galaxyand radiative cooling are important for the formation of a gaseous plumeextending from the disk of a target galaxy. A noticeable plume structure can beformed if the mass of an intruder is a few percent of the mass of the primary. The halo of the intruder is stripped in the collision, and dispersedparticles form a broad stellar bridge connecting the two galaxies. The fractionof the intruder's halo dispersed in the collision depends on the total mass ofthe intruder, and low-mass intruders lose most of their mass.Comment: 15 pages, 14 figures in GIF. To appear ApJ. Vol. 505 #