Modelling chemical abundance distributions for dwarf galaxies in the Local Group: The impact of turbulent metal diffusion

Ivanna Escala, Andrew Wetzel, Evan N. Kirby, Philip F. Hopkins, Xiangcheng Ma, Coral Wheeler, Dušan Kereš, Claude André Faucher-Giguère, Eliot Quataert

Research output: Contribution to journalArticle

32 Scopus citations

Abstract

We investigate stellar metallicity distribution functions (MDFs), including Fe and a-element abundances, in dwarf galaxies from the Feedback in Realistic Environment (FIRE) project. We examine both isolated dwarf galaxies and those that are satellites of a MilkyWay-mass galaxy. In particular, we study the effects of including a sub-grid turbulent model for the diffusion of metals in gas. Simulations that include diffusion have narrower MDFs and abundance ratio distributions, because diffusion drives individual gas and star particles towards the average metallicity. This effect provides significantly better agreement with observed abundance distributions in dwarf galaxies in the Local Group, including small intrinsic scatter in [α/Fe] versus [Fe/H] of ≲0.1 dex. This small intrinsic scatter arises in our simulations because the interstellar medium in dwarf galaxies is well mixed at nearly all cosmic times, such that stars that form at a given time have similar abundances to ≲0.1 dex. Thus, most of the scatter in abundances at z = 0 arises from redshift evolution and not from instantaneous scatter in the ISM. We find similar MDF widths and intrinsic scatter for satellite and isolated dwarf galaxies, which suggests that environmental effects play a minor role compared with internal chemical evolution in our simulations. Overall, with the inclusion of metal diffusion, our simulations reproduce abundance distribution widths of observed low-mass galaxies, enabling detailed studies of chemical evolution in galaxy formation.

Original languageEnglish (US)
Pages (from-to)2194-2211
Number of pages18
JournalMonthly Notices of the Royal Astronomical Society
Volume474
Issue number2
DOIs
StatePublished - 2018

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Diffusion
  • Galaxies: abundances
  • Galaxies: dwarf
  • Local Group
  • Methods: numerical

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