A minor-merger origin for inner disks and rings in early-type galaxies
  Nuclear disks and rings are frequent galaxy substructures, for a wide range
of morphological types (from S0 to Sc). We have investigated the possible
minor-merger origin of inner disks and rings in spiral galaxies through
collisionless N-body simulations. The models confirm that minor mergers can
drive the formation of thin, kinematically-cold structures in the center of
galaxies out of satellite material, without requiring the previous formation of
a bar. Satellite core particles tend to be deposited in circular orbits in the
central potential, due to the strong circularization experienced by the
satellite orbit through dynamical friction. The material of the satellite core
reaches the remnant center if satellites are dense or massive, building up a
thin inner disk; whereas it is fully disrupted before reaching the center in
the case of low-mass satellites, creating an inner ring instead.
