AAS 203rd Meeting, January 2004
Session 105 Dwarf, Irregular, LUM IR and Starburst Galaxies
Oral, Wednesday, January 7, 2004, 2:00-3:30pm, Regency VII

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[105.05] Inner Halo Shapes of Dwarf Galaxies: Reconciling the Cusp/Core Problem

K. Spekkens, R. Giovanelli (Cornell University)

We derive inner dark matter halo density profiles for a sample of 200 dwarf galaxies by inverting rotation curves obtained from high-quality, long-slit optical spectra. Each galaxy in the sample shows no evidence for a bulge, bar or other baryonic distortions as determined by accurate I-band photometry. For \rho(r) ~ r-\alpha near the galaxy center we obtain a distribution of measured inner profile slopes \alpham that peaks at \alpham~ 0.3, similar to values found by other authors (e.g. de Blok et al. 2003, Swaters et al. 2003), and in stark contrast to the intrinsic cusps (\alphaint~ 1) predicted by simulations of halo assembly in CDM cosmologies. To assess the severity of the discrepancy between our results and CDM predictions, we simulate long-slit observations of a population of intrinsically cuspy (\alphaint =1) dwarf halos. The large sample size in this study permits a quantitative comparison between theory and observations, in which the impact of a variety of observational and data processing biases can be analyzed in a statistically significant manner. Our simulations recover both the observed distribution of \alpham and correlations between \alpham and primary observational parameters such as distance and disk inclination. We conclude that, in our long-slit spectroscopy data sample, the observations are consistent with cuspy halos as predicted by the CDM paradigm without recourse to halo triaxiality, modifications of Newtonian dynamics or other exotic phenomena. This work is partially funded by NSF grants AST-9900695 and AST-0307661.

The author(s) of this abstract have provided an email address for comments about the abstract: spekkens@astro.cornell.edu

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.