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Eric Andersson. Profile Picture

Eric Andersson

Doctoral student

Eric Andersson. Profile Picture

EDGE : The sensitivity of ultra-faint dwarfs to a metallicity-dependent initial mass function

Author

  • Mateo Prgomet
  • Martin P. Rey
  • Eric P. Andersson
  • Alvaro Segovia Otero
  • Oscar Agertz
  • Florent Renaud
  • Andrew Pontzen
  • Justin I. Read

Summary, in English

Motivated by the observed bottom-light initial mass function (IMF) in faint dwarfs, we study how a metallicity-dependent IMF affects the feedback budget and observables of an ultra-faint dwarf galaxy. We model the evolution of a low-mass 8 × 108 M⊙) dark matter halo with cosmological, zoomed hydrodynamical simulations capable of resolving individual supernovae explosions, which we complement with an empirically motivated subgrid prescription for systematic IMF variations. In this framework, at the low gas metallicities typical of faint dwarfs, the IMF of newborn stellar populations becomes top-heavy, increasing the efficiency of supernova and photoionization feedback in regulating star formation. This results in a 100-fold reduction of the final stellar mass of the dwarf compared to a canonical IMF, at fixed dynamical mass. The increase in the feedback budget is none the less met by increased metal production from more numerous massive stars, leading to nearly constant iron content at z = 0. A metallicity-dependent IMF therefore provides a mechanism to produce low-mass (M* ∼ 103 M⊙), yet enriched ([Fe/H] -2) field dwarf galaxies, thus opening a self-consistent avenue to populate the plateau in [Fe/H] at the faintest end of the mass-metallicity relation.

Department/s

  • Lund Observatory

Publishing year

2022-06-01

Language

English

Pages

2326-2334

Publication/Series

Monthly Notices of the Royal Astronomical Society

Volume

513

Issue

2

Document type

Journal article

Publisher

Oxford University Press

Topic

  • Astronomy, Astrophysics and Cosmology

Keywords

  • galaxies: Dwarf
  • galaxies: Evolution
  • galaxies: Formation
  • methods: Numerical

Status

Published

ISBN/ISSN/Other

  • ISSN: 0035-8711