Fornax 3 Core

The Fornax dwarf spheroidal galaxy hosts five globular clusters — an unusually high number for a system of its stellar mass — and the innermost of these, Fornax 3, is the most massive and sits near the galaxy's center at a projected separation of only ~0.24 kpc. The puzzle is one of dynamical survival: N-body simulations robustly predict that dynamical friction should cause a massive globular cluster at this orbital radius to sink to the center of the host galaxy within a few Gyr, yet Fornax 3 and its companions have apparently survived in their current configuration for many billions of years. In a standard CDM cuspy halo, this sinking timescale problem is acute; proposed resolutions invoking a central density core reduce the dynamical friction but require specific dark matter density profiles that are themselves in tension with other observations of Fornax's kinematics.

Successive Collision Theory resolves the Fornax 3 sinking problem through the same core-formation mechanism that addresses the broader core-cusp tension. The inherited angular momentum of Fornax's collision debris stratum established a centrifugal barrier at formation that prevented a central density cusp from developing. Without a central cusp, the dynamical friction force on Fornax 3 is dramatically reduced: dynamical friction scales steeply with local density, so a flat central density core produces orders of magnitude less friction than an NFW-like cusp at the same total enclosed mass. Fornax 3 therefore does not sink because the gravitational environment it inhabits is not the cuspy environment that CDM predicts — it orbits in a flat-density core sustained by the primordial angular momentum barrier of the debris field.

The gravitational superposition contribution from the nested frame hierarchy further stabilizes the cluster's orbit by providing a smooth, extended mass distribution that does not steepen toward the center. SCT predicts that the survival of multiple globular clusters within dwarf spheroidals is not a coincidence requiring fine-tuned initial conditions but a generic consequence of the flat-core environments that angular momentum inheritance produces in all collision debris structures at this mass scale. The correlation between core size and globular cluster survival fraction across the dwarf spheroidal population — multiple systems with flat cores retain their clusters while cuspy systems do not — is a testable prediction that distinguishes the SCT framework from CDM-plus-feedback models in which core sizes vary case-by-case with the stochastic supernova history.