Martin Weinberg (UMass)
"Bars, Cusps, and Cores"


Simulations predict that the dark matter halos of galaxies should have central cusps, while those inferred from observed galaxies do not have cusps. I will describe the evolution of a cuspy halo by a disk bar and show that a disk bar, which should be ubiquitous in forming galaxies, can produce cores in cuspy CDM dark matter profiles within 5 bar orbital times. The dynamical mechanisms involved here are general to all interactions between the disk, satellites and a dark-matter halo. In particular, both the bar-cusp and satellite-cusp coupling depends on near-resonant dynamics. I will demonstrate that simulations with very high resolution are required to suppress the small-scale noise and resolve the dynamics properly.

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