A Critical Assessment of Solutions to the Galaxy Diversity Problem
  Galactic rotation curves exhibit a diverse range of inner slopes.
Observational data indicates that explaining this diversity may require a
mechanism that correlates a galaxy's surface brightness with the central-most
region of its dark matter halo. In this work, we compare several concrete
models that capture the relevant physics required to explain the galaxy
diversity problem. We focus specifically on a Self-Interacting Dark Matter
(SIDM) model with an isothermal core and two Cold Dark Matter (CDM) models
with/without baryonic feedback. Using rotation curves from 90 galaxies in the
Spitzer Photometry and Accurate Rotation Curves (SPARC) catalog, we perform a
comprehensive model comparison that addresses issues of statistical methodology
from prior works. The best-fit halo models that we recover are consistent with
the Planck concentration-mass relation as well as standard abundance matching
relations. We find that both the SIDM and feedback-affected CDM models are
better than a CDM model with no feedback in explaining the rotation curves of
low and high surface brightness galaxies in the sample. However, when compared
to each other, there is no strong statistical preference for either the SIDM or
the feedback-affected CDM halo model as the source of galaxy diversity in the
SPARC catalog.
