  Models of debris disk morphology are often focused on the effects of a planet
orbiting interior to or within the disk. Nonetheless, an exterior
planetary-mass perturber can also excite eccentricities in a debris disk, via
Laplace-Lagrange secular perturbations in the coplanar case or Kozai-Lidov
perturbations for mutually inclined companions and disks. HD 106906 is an ideal
example of such a system, as it harbors a confirmed exterior 11 M_Jup companion
at a projected separation of 650 au outside a resolved, asymmetric disk. We use
collisional and dynamical simulations to investigate the interactions between
the disk and the companion, and to use the disk's observed morphology to place
constraints on the companion's orbit. We conclude that the disk's observed
morphology is consistent with perturbations from the observed exterior
companion. Generalizing this result, we suggest that exterior perturbers, as
well as interior planets, should be considered when investigating the cause of
observed asymmetries in a debris disk.
