Determine the impact of three-dimensional effects on retrograde minidisks

Determine whether retrograde minidisks around eccentric supermassive black hole binaries remain stable when three-dimensional out-of-plane dynamics, including disk warping and tilting, are modeled.

Background

The simulations solve vertically integrated two-dimensional hydrodynamic equations and therefore suppress disk warping and other out-of-plane dynamics. Previous studies cited in the paper indicate that retrograde minidisks may be unstable to out-of-plane tilting in three dimensions.

Establishing the stability of the minidisks in fully three-dimensional simulations is important because such instabilities could alter their structure, spin orientation, angular-momentum exchange, and the predicted orbital evolution of the binary.

References

Finally, by solving the vertically integrated equations we suppress all out-of-plane dynamics, including disk warping. and find that retrograde minidisks may be unstable to out-of-plane tilting in 3D, suggesting this is a potentially significant limitation of our 2D framework.

— Electromagnetic Emission and Orbital Evolution of Eccentric Supermassive Black Hole Binaries in Retrograde Disks  (2609.09314 - ONeill et al., 8 Sep 2026) in Section 5.3, Instability Analysis; Section 5.4, Caveats