MOND or another theory giving rise to a comparable effect is necessary and sufficient to explain galaxy dynamics. This is hard to do with dark matter particle theories.
to explain statistically late-type galaxy dynamics within the disk it is necessary and sufficient to explain the RAR and lack of any significant, partially independent correlation. While simple in some modified dynamics models, this poses a challenge to standard cosmology.
It basically can't be done in a cold dark matter theory.
Before halo compression, high-mass galaxies approximately lie on the observed RAR whereas low-mass galaxies display up-bending "hooks" at small radii due to DM cusps, making them deviate systematically from the observed relation. After halo compression, the initial NFW halos become more concentrated at small radii, making larger contributions to rotation curves. This increases the total accelerations, moving all model galaxies away from the observed relation. These systematic deviations suggest that the CDM model with abundance matching alone cannot explain the observed RAR. Further effects (e.g., feedback) would need to counteract the compression with precisely the right amount of halo expansion, even in high mass galaxies with deep potential wells where such effects are generally predicted to be negligible.
Cosmology also continue to be a problem for the LambdaCDM model.
We establish a new and cosmological-model-independent method to explore the cosmic background dynamics in this work. Utilizing the latest Pantheon+ type Ia supernova sample and the Hubble parameter measurements, we obtain the values of the Hubble parameter and the deceleration parameter at five different redshift points ranging from 0.2 to 0.6, and find that they can deviate from the predictions of the ΛCDM model at more than 2σ. We further probe the equation of state of dark energy and obtain that a slightly oscillating equation of state of dark energy around the −1 line is favored.
Milgrom, meanwhile, considers a version of MOND that is matter distribution shape dependent, which was critical to Deur's generalization of the gravitational approach to dark matter to a wider range of applicability.