Debris disks are scaled-up analogs of the Kuiper Belt in which dust is generated by collisions between planetesimals. A foundation of our understanding of debris disks is the concept of a \"collisional cascade,\" where the mass loss from radiation pressure within a disk is replenished by larger planetesimals colliding with smaller bodies. One standard assumption of this model is that the collisions are destructive and involve large velocities, but this assumption has not been tested outside of the Solar System. We present 0.25\" resolution observations of the λ = 450 μm dust continuum emission from the debris disk around the nearby M dwarf AU Microscopii with the Atacama Large Millimeter/submillimeter Array. We use parametric MCMC models to fit the structure of the disk to both our data and existing λ = 1.3 mm data (Daley et al. 2019), from which we derive the velocity dispersion and grain size distribution indices of the disk. Interpreting our results within the modeling framework laid out in Pan & Schlichting (2012), we find that the AU Mic debris disk's collisional behavior lies within the \"gravity regime\" where catastrophic collisions significantly damp the velocities of bodies within the disk. This marks the first parameterization of a collisional cascade in a disk beyond our Solar System.
"},{"label":"Degree","value":["Bachelor of Arts with Departmental Honors"]},{"label":"Author-supplied Keywords","value":["Astrophysics","Debris disk","AU Mic"]},{"label":"Administrative Note","value":"Access was restricted until April 15, 2022.