paper

The role of faint population III supernovae in forming CEMP stars in ultra-faint dwarf galaxies

arXiv:2012.10012 · doi:10.1093/mnras/staa4017

Abstract

CEMP-no stars, a subset of carbon enhanced metal poor (CEMP) stars ( and ) have been discovered in ultra-faint dwarf (UFD) galaxies, with Msun and Msun at , as well as in the halo of the Milky Way (MW). These CEMP-no stars are local fossils that may reflect the properties of the first (Pop~III) and second (Pop~II) generation of stars. However, cosmological simulations have struggled to reproduce the observed level of carbon enhancement of the known CEMP-no stars. Here we present new cosmological hydrodynamic zoom-in simulations of isolated UFDs that achieve a gas mass resolution of Msun. We include enrichment from Pop~III faint supernovae (SNe), with erg, to understand the origin of CEMP-no stars. We confirm that Pop~III and Pop~II stars are mainly responsible for the formation of CEMP and C-normal stars respectively. New to this study, we find that a majority of CEMP-no stars in the observed UFDs and the MW halo can be explained by Pop~III SNe with normal explosion energy (~erg) and Pop~II enrichment, but faint SNe might also be needed to produce CEMP-no stars with , corresponding to the absolute carbon abundance of . Furthermore, we find that while we create CEMP-no stars with high carbon ratio , by adopting faint SNe, it is still challenging to reproduce CEMP-no stars with extreme level of carbon abundance of , observed both in the MW halo and UFDs.

14 pages, 8 figures, submitted to MNRAS

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