Following The Cosmic Evolution Of Pristine Gas I: Implications For Milky Way Halo Stars
2016
We make use of new subgrid model of turbulent mixing to accurately follow the cosmological evolution of the first
stars, the mixing of their supernova
ejecta, and the impact on the chemical composition of the
Galactic Halo. Using the cosmological
adaptive mesh refinementcode RAMSES, we implement a model for the pollution of pristine gas as described in Pan et al. (2013). Tracking the metallicity of Pop III
starswith metallicities below a critical value allows us to account for the fraction of Z < Zcrit
starsformed even in regions in which the gas' average metallicity is well above Zcrit. We demonstrate that such partially-mixed regions account for 0.5 to 0.7 of all Pop III
starsformed up to z = 5. Additionally, we track the creation and transport of "primordial metals" generated by Pop III supernovae (SNe). These metals are taken up by second-generation
starsand likely lead to unique abundance signatures characteristic of carbon enhanced, metal poor (CEMP)
stars. As an illustrative example, we associate primordial metals with abundance ratios used by Keller et al. (2014) to explain the source of metals in the
starSMSS J031300.36-670839.3, finding good agreement with the observed [Fe/H], [C/H], [O/H] and [Mg/Ca] ratios in CEMP Milky Way (MW) halo
stars. Similar future simulations will aid in further constraining the properties of Pop III
starsusing CEMP observations, as well as improve predictions of the spatial distribution of Pop III
stars, as will be explored by the next generation of ground and space-based telescopes.
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