Shell Galaxies: Dynamical Friction, Gradual Satellite Decay and Merger
  Dating
  With the goal to refine modelling of shell galaxies and the use of shells to
probe the merger history, we develop a new method for implementing dynamical
friction in test-particle simulations of radial minor mergers. The friction is
combined with a gradual decay of the dwarf galaxy. The coupling of both effects
can considerably redistribute positions and luminosities of shells; neglecting
them can lead to significant errors in attempts to date the merger.
