  We explore the secular dynamical evolution of an N-body model of M31 in the
presence of a population of 100 dark matter satellites over 10 Gyr. The
satellite population has structural and kinematic characteristics modelled to
follow the predictions of Lambda-CDM cosmological simulations. Vertical disk
heating is a small effect despite many interactions with the satellite
population with only a 20% increase in vertical velocity dispersion sigma_z and
the disk scale height z_d at the equivalent solar radius R = 2.5R_d . However,
the stellar disk is noticeably flared after 10 Gyr with z_d nearly doubling at
the disk edge. Azimuthal disk heating is much larger with sigma_R and sigma_z
both increasing by 1.7x. However, in a control experiment without satellites
dispersion increases by 1.5x suggesting that most of the effect is due to
heating through scattering off of spiral structure excited by swing-amplified
noise. Surprisingly, direct impacts of satellites on the disk can excite spiral
structure with a significant amplitude and in some cases impacts close to the
disk center also induce the bar instability. The large number of dark matter
satellite impacts expected over a galaxy's lifetime may be a significant source
of external perturbations for driving disk secular evolution.
