2002ApJ...565..238B

We have obtained ∼100 pc resolution CO and ∼60 pc resolution Hα observations of the dwarf spiral galaxy NGC 4605. We use them to derive a high-resolution rotation curve and study the central density profile of NGC 4605's dark matter halo. We find that these observations do not agree with the predictions of most high-resolution cold dark matter calculations. We investigate two extreme cases: (1) NGC 4605 has a maximal exponential disk, which we model using K-band observations and remove to study the structure of its dark matter halo, and (2) NGC 4605 is dark matter-dominated, and its disk is dynamically negligible. Because the mass-to-light ratio of the maximal disk is already very low, we favor the first solution, which indicates the halo has one component with a density profile ρ∝r^–0.65 out to R∼2.8 kpc. In the second case, the rotation curve requires the presence of two components: a small (∼600 pc) core surrounded by a much steeper ρ∝r^–1.1 halo. Removal of intermediate (submaximal) disks does not ameliorate the discrepancy between the predictions and the observations.