Cuspy dark matter density profiles in massive dwarf galaxies
  Rotation curves of galaxies probe their total mass distributions, including
dark matter. Dwarf galaxies are excellent systems to investigate the dark
matter density distribution, as they tend to have larger fractions of dark
matter compared to higher mass systems. The core-cusp problem describes the
discrepancy found in the slope of the dark matter density profile in the
centres of galaxies ($\beta^*$) between observations of dwarf galaxies
(shallower cores) and dark matter-only simulations (steeper cusps). We
investigate $\beta^*$ in six nearby spiral dwarf galaxies for which
high-resolution CO $J=1-0$ data were obtained with ALMA. We derive rotation
curves and decompose the mass profile of the dark matter using our CO rotation
curves as a tracer of the total potential and 4.5$\mu$m photometry to define
the stellar mass distribution. We find $\langle\beta^*\rangle = 0.6$ with a
standard deviation of $\pm0.1$ among the galaxies in this sample, in agreement
with previous measurements in this mass range. The galaxies studied are on the
high stellar mass end of dwarf galaxies and have cuspier profiles than lower
mass dwarfs, in agreement with other observations. When the same definition of
the slope is used, we observe steeper slopes than predicted by the FIRE and
NIHAO simulations. This may signal that these relatively massive dwarfs
underwent stronger gas inflows toward their centres than predicted by these
simulations, that these simulations over-predict the frequency of accretion or
feedback events, or that a combination of these or other effects are at work.
