Tidal features in classical Milky Way satellites match MOND predictions but exceed CDM resilience thresholds

The study computed tidal susceptibility for the nine classical satellites by placing their observed half-mass radii against theoretical tidal radii derived from Milky Way mass models at pericentric distances. In CDM this ratio remains well below unity for all objects because massive dark halos supply strong self-gravity; in MOND the ratio exceeds one for seven satellites, correctly forecasting the tidal tails, shells and shape distortions already mapped by Gaia and DES. The same MOND tides also inject kinetic energy that raises line-of-sight velocity dispersions, offering a dynamical explanation for the inflated values reported for Draco and Ursa Minor without invoking extra dark matter. This constitutes a direct, falsifiable test of gravity on galactic scales using only photometry and orbits already in hand.

Standard CDM simulations of satellite populations predict that subhalos massive enough to host the classical dwarfs retain their stellar components against Milky Way tides for many Gyr. The observed disturbances therefore require either extreme fine-tuning of orbital parameters or a revision of the assumed halo density profiles. MOND sidesteps this tension because the external field effect weakens the satellites' effective gravity near pericenter without any additional parameters. The result therefore isolates the gravitational regime rather than the baryonic physics that usually complicates dwarf-galaxy comparisons.

Future Gaia DR4 proper motions and deeper imaging from LSST will tighten pericenter distances and map fainter tidal debris. If the fraction of disturbed satellites remains near 80 percent while their velocity-dispersion profiles continue to match MOND heating curves, the discrepancy with CDM will become statistically decisive. Conversely, discovery of a population of undisturbed ultra-faint satellites on similar orbits would restore tension for MOND.