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Applicability of the standard gap-opening criterion in gravitoturbulent disks

Determine whether the standard gap-opening criterion q ≳ 5 h^(5/2) α^(1/2), calibrated for viscous disks with α ≪ 1, remains valid in gravitoturbulent protostellar disks where the effective α can be of order unity.

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Background

Following fragmentation, clumps may accrete and interact with the disk, potentially opening gaps that strongly affect subsequent migration and growth. The widely used gap-opening threshold is derived for viscous, laminar disks with small α.

In gravitoturbulent disks, α can be much larger, and strong spiral and clump-driven perturbations may change the applicability of the standard criterion. The authors explicitly note this uncertainty.

References

We caution that the above threshold is calibrated with viscous disks with α ≪ 1, and it is not obvious whether it remains applicable in the presence of gravitortubulence at order-unity α.

— Global Simulations of Gravitational Instability in Protostellar Disks with Full Radiation Transport. I. Stochastic Fragmentation with Optical-depth-dependent Rate and Universal Fragment Mass (2410.12042 - Xu et al., 15 Oct 2024) in Section 5.2