Reconciling the Diversity and Uniformity of Galactic Rotation Curves with Self-Interacting Dark Matter

TL;DR

This paper demonstrates that self-interacting dark matter can naturally explain the diverse inner rotation curves of galaxies while maintaining a universal radial acceleration relation, aligning with cosmological and astrophysical observations.

Contribution

It shows that dark matter self-interactions lead to thermalized inner halos, reproducing observed galaxy rotation curve diversity and uniformity within a hierarchical formation framework.

Findings

Reproduces galaxy rotation curve diversity and uniformity with self-interacting dark matter.

Consistent dark matter halo concentrations with Planck cosmology.

Stellar mass-to-light ratios align with population synthesis models.

Abstract

Galactic rotation curves exhibit diverse behavior in the inner regions, while obeying an organizing principle, i.e., they can be approximately described by a radial acceleration relation or the Modified Newtonian Dynamics phenomenology. We analyze the rotation curve data from the SPARC sample, and explicitly demonstrate that both the diversity and uniformity are naturally reproduced in a hierarchical structure formation model with the addition of dark matter self-interactions. The required concentrations of the dark matter halos are fully consistent with the concentration-mass relation predicted by the Planck cosmological model. The inferred stellar mass-to-light ($3.6 \mu m$) ratios scatter around $0.5 M_\odot/L_\odot$, as expected from population synthesis models, leading to a tight radial acceleration relation and baryonic Tully-Fisher relation. The inferred stellar-halo mass relation is consistent with the expectations from abundance matching. These results indicate that the inner dark matter halos of galaxies are thermalized due to the self-interactions of dark matter particles.