Speaker
Description
High-resolution kinematic measurements of disc galaxies continue to exhibit a persistent mismatch between the observed rotation curves and the distribution of visible components, reinforcing either the necessity for a "dark" matter component or a departure from standard gravitational dynamics in the low-acceleration regime. We present the modelled rotation curves of 115 disc-dominated late-type spiral galaxies from the SPARC database, using a suite of models including Cold Dark Matter (CDM) models with and without baryonic feedback, Warm DM, Fuzzy DM, and Modified Newtonian Dynamics (MOND) in order to assess their relative performance and highlight any degeneracies. We find that no model can be safely excluded by current data, although we find a mild evidence for a preference for CDM models with baryonic feedback. However, when including the weak lensing data of the mean galaxy rotation curves of low-mass galaxies out to ∼ 1 Mpc, we find a nearly perfect degeneracy between MOND and DM models, at least up to the virial radius. We further test all the models against the global scaling relations of galaxy luminosity versus halo mass and circular velocity, as inferred from abundance matching, or the radial acceleration relation, finding that all models again predict very similar trends, with exceptionally narrow scatter around the luminosity-circular velocity relation. The increased scatter observed around the luminosity-halo mass relation exhibited by some of the models can be largely attributed to the limited radial extent of certain rotation curves, particularly in cases where the data do not probe sufficiently near the maximum circular velocity. We confirm a degeneracy between MOND and CDM also in the outputs of the TNG50 hydrodynamic simulation which predicts that, despite differences in internal structure, a traditional CDM model inclusive of baryonic feedback is consistent with all rotation curves up to the virial radius as inferred from weak lensing analysis. Finally, we will show preliminary results on the comparison between some z~1-2 galaxies with detailed rotation curve measurements and the predictions from our best MOND and CDM with baryonic feedback models against, to test their performance in a very different regime.