Formation of Plumes in Head-on Collisions of Galaxies

摘要

Using N-body and smoothed particle hydrodynamics modeling we perform three-dimensional numerical simulations of head-on collisions between gas-rich disk galaxies, including collisions between counterrotating disks and off-center collisions. Pure stellar intruders do not produce gaseous plumes similar to those seen in the Cartwheel and ZW VII 466 complexes of interacting galaxies; the presence of gas in an intruder galaxy and radiative cooling are important for the formation of a gaseous plume extending from the disk of a target galaxy. A noticeable plume structure can be formed 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 dispersed particles form a broad stellar bridge connecting the two galaxies. The fraction of the intruder's halo dispersed in the collision depends on the total mass of the intruder, and low-mass intruders lose most of their mass.