A Common-Progenitor for Metis and Adrastea?

Metis and Adrastea are Jupiter’s two innermost satellites and are notable for having semi-major axes that are very close to one another: approximately 1,000 km separate their quasi-circular orbits. Both are located below Jupiter’s synchronous radius, below the fluid Roche limit, and slightly above the rigid Roche limit. The origin of this pair remains poorly constrained. Burns et al. (2004), however, suggested that the proximity of their orbits could be an argument in favor of a formation through the fragmentation of a common progenitor. In addition to the aforementioned elements, the tidal migration of Metis and Adrastea following the fragmentation of a common progenitor may have shaped the satellites’ present-day orbits. 
In the present work, we use N-body integrations to simulate the dynamics following this potential fragmentation, considering Jupiter's J₂ and J₄ gravitational harmonics, while including tidal forces. By varying the initial separation, fragment masses, and tidal parameters, we assess the dynamical survival of two-body outcomes and the conditions under which the fragments can evolve toward orbits comparable to those observed today.