A new theoretical model proposes that Q-balls of dark matter, non-topological solitons stabilized by a conserved charge, could resolve the "cusp-core" problem in galaxies. This problem refers to the discrepancy between cosmological predictions of a sharp dark matter density profile in the center of galaxies and observations, which suggest flatter profiles or "cores." The mechanism proposed by Q-balls offers a dynamic explanation for this flattening, without requiring drastic modifications to the standard cosmological model.

Q-balls would form in the early universe within the dark sector and grow in the dense regions of galactic halos. Their interaction cross-section would decrease as their soliton mass increases. This process preferentially operates in halo centers, converting part of the rest-mass energy stored in massive Q-balls into relativistic dark-sector particles. This energy flow modifies the inner mass-density profile, flattening the cusp.

The key to the mechanism lies in a self-regulating, density-dependent energy loss. This dynamic process allows the dark matter halo density cusps to be flattened in their central regions, leaving the outer parts of the halo largely unaffected. This model could explain the observed diversity in inner rotation curves and central densities of galaxies for a fixed halo mass, offering an elegant solution to one of the persistent tensions in the standard cold, collisionless dark matter model at galactic scales.