Formation of Compact Stellar Clusters by High-Redshift Galaxy Outflows I: Nonequillibrium Coolant Formation

Abstract

We use high-resolution three-dimensional adaptive mesh refinement simulations to investigate the interaction of high-redshift galaxy outflows with low-mass virialized clouds of primordial composition. While atomic cooling allows star formation in objects with virial temperatures above $10^4$ K, "minihaloes" below this threshold are generally unable to form stars by themselves. However, these objects are highly susceptible to triggered star formation, induced by outflows from neighboring high-redshift starburst galaxies. Here we conduct a study of these interactions, focusing on cooling through non-equilibrium molecular hydrogen (H${}_2$) and hydrogen deuteride (HD) formation. Tracking the non-equilibrium chemistry and cooling of 14 species and including the presence of a dissociating background, we show that shock interactions can transform minihaloes into extremely compact clusters of coeval stars. Furthermore, these clusters are all less than $\approx 10^6{M}_{\odot },$ and they are ejected from their parent dark matter halos: properties that are remarkably similar to those of the old population of globular clusters.

17 pages, 14 figures, ApJ in press

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• The Launching of Cold Clouds by Galaxy Outflows II: The Role of Thermal Conduction
• Mixing of Clumpy Supernova Ejecta into Molecular Clouds
• The Launching of Cold Clouds by Galaxy Outflows III: The Influence of Magnetic Fields
• Catastrophic Cooling in Superwinds: Line Emission and Non-equilibrium Ionization
• The Launching of Cold Clouds by Galaxy Outflows. IV. Cosmic-Ray-Driven Acceleration
• Evidence for inhomogeneous reionization in the local Universe from metal-poor globular cluster systems
• Hybrid Cosmological Simulations with Stream Velocities
• Atomic Chemistry In Turbulent Astrophysical Media I: Effect of Atomic Cooling
• Galaxy Outflows Without Supernovae
• Impact of an accurate modeling of primordial chemistry in high resolution studies
• Non-equilibrium Ionization States Within Galactic Outflows: Explaining Their O VI and N V Column Densities
• Formation of Compact Stellar Clusters by High-Redshift Galaxy Outflows II: Effect of Turbulence and Metal-Line Cooling
• Column Density Profiles of Cold Clouds Driven by Galactic Outflows
• Identification of a Fundamental Transition in a Turbulently-Supported Interstellar Medium
• Thermal and Chemical Evolution of Collapsing Filaments
• Formation of Compact Stellar Clusters by High-Redshift Galaxy Outflows III: Observability and Connection to Halo Globular Clusters
• Formation of Compact Clusters from High Resolution Hybrid Cosmological Simulations