The Density Profile of the Dark Matter Halo of NGC 4605 (original) (raw)
ADS
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Abstract
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.
Publication:
The Astrophysical Journal
Pub Date:
January 2002
DOI:
10.48550/arXiv.astro-ph/0108050
arXiv:
Bibcode:
Keywords:
- Cosmology: Dark Matter;
- Galaxies: Dwarf;
- Galaxies: Halos;
- galaxies: individual (NGC 4605);
- Galaxies: Kinematics and Dynamics;
- Radio Lines: Galaxies;
- Astrophysics
E-Print:
8 pages, 5 figures. Revised version (minor changes), accepted for publication in The Astrophysical Journal. Also available at http://astron.berkeley.edu/\~bolatto/