Tidal disruption of dark matter halos around proto-globular clusters

Tidal disruption of dark matter halos around proto-globular clusters in the halo of a small galaxy is studied in the context of the hierarchical clustering scenario by using semicosmological N-body/SPH simulations assuming the standard cold dark matter model (Ω₀ = 1). Our analysis on the formation and evolution of the galaxy and its substructures continues until z = 2.0. In such a high-redshift universe, the Einstein-de Sitter universe is still a good approximation for the recently favored ∧-dominated universe, and thus our results do not depend on the choice of cosmology. In order to resolve small gravitationally bound clumps around galaxies and consider radiative cooling below T = 10⁴ K, we adopt a fine mass resolution (m_SPH = 1.12 × 10³ M_⊙). Because of the cooling, each clump immediately forms a "core-halo" structure that consists of a baryonic core and a dark matter halo. The tidal force from the host galaxy mainly strips the dark matter halo from clumps, and as a result, these clumps get dominated by baryons. Once a clump is captured by the host halo, its mass drastically decreases with each pericenter passage. At z = 2, more than half of the clumps become baryon-dominated systems (baryon mass/total mass > 0.5). Our results support the tidal evolution scenario of the formation of globular clusters and baryon-dominated dwarf galaxies in the context of the cold dark matter universe.