Origin of differences between low- and high-mass GI disks

Ascertain whether the observed differences between low disk-to-star mass ratio disks and high disk-to-star mass ratio disks in gravitational instability—particularly in the nature of spiral structure and transport—arise from fundamentally different dynamics, or whether both share the same dynamics with the typical perturbation scale and the deviation from local viscosity scaling with the disk scale height H.

Background

There is an apparent tension between modeling spiral substructures via global eigenmodes and modeling transport via a local viscosity prescription. Simulations suggest increasing global behavior with higher disk mass, but it is unclear whether this reflects different physics or a unified mechanism with different characteristic scales.

Clarifying this distinction is important for building consistent theoretical and observational models of gravitoturbulence and spiral structure across disk masses.