  We study how massive halos respond to perturbations. Through numerical
solution of the coupled linearized Boltzmann-Poisson equations, we find that
halos transmit and amplify disturbances over large distances within galaxies.
In particular, as Weinberg has noted, the halo provides an excellent medium for
transmitting disturbances from the outer regions of galaxies to the inner
regions. The dipolar response typically dominates and, in some cases, is very
weakly damped. The monopole and quadrupole response can also make significant
contributions. Overall, the results support the notion that disk structure can
be excited by transmission of noise from the distant halo. The strong dipolar
response suggests that halos play a role in producing lopsided disks. These
results also suggest that, during formation from initial collapse, halos do not
settle rapidly into static equilibrium: instead, they may continue to ring and
interact with other embryonic components of the proto-galaxy
