Sinking Satellites and Disk Heating of Spiral Galaxies
Most large galaxies possess a system of smaller satellite companions, such as the Magellanic Clouds around our own galaxy. Dynamical friction on the luminous body of the primary galaxy and its dark halo will lead to the decay of satellite orbits and some companions may eventually be assimilated by the large galaxy. For disk primaries, the kinetic energy available from a satellite accretion can easily be comparable to the total vertical kinetic energy of the disk. In such cases, the primary will be significantly perturbed by an accretion and perhaps destroyed by continued bombardment.