paper

Dark Matter Subhalos in the Ursa Minor Dwarf Galaxy

arXiv:1207.5681 · doi:10.1088/0004-637X/757/1/87

Abstract

Through numerical simulations, we study the dissolution timescale of the Ursa Minor cold stellar clump, due to the combination of phase-mixing and gravitational encounters with compact dark substructures in the halo of Ursa Minor. We compare two scenarios; one where the dark halo is made up by a smooth mass distribution of light particles and one where the halo contains 10% of its mass in the form of substructures (subhalos). In a smooth halo, the stellar clump survives for a Hubble time provided that the dark matter halo has a big core. In contrast, when the point-mass dark substructures are added, the clump survives barely for \sim 1.5 Gyr. These results suggest a strong test to the Λ-cold dark matter scenario at dwarf galaxy scale.

accepted for publication in ApJ

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