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

Prgomet, Mateo ; Rey, Martin P. LU ; Andersson, Eric P. LU ; Segovia Otero, Alvaro LU ; Agertz, Oscar LU ; Renaud, Florent LU ; Pontzen, Andrew and Read, Justin I. (2022) In Monthly Notices of the Royal Astronomical Society 513(2). p.2326-2334
Abstract

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... (More)

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.

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author
; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
galaxies: Dwarf, galaxies: Evolution, galaxies: Formation, methods: Numerical
in
Monthly Notices of the Royal Astronomical Society
volume
513
issue
2
pages
9 pages
publisher
Oxford University Press
external identifiers
  • scopus:85130492245
ISSN
0035-8711
DOI
10.1093/mnras/stac1074
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
id
a19cd246-d711-4db6-a942-b03198fbaa3c
date added to LUP
2022-08-19 12:43:58
date last changed
2024-04-18 05:04:44
@article{a19cd246-d711-4db6-a942-b03198fbaa3c,
  abstract     = {{<p>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.</p>}},
  author       = {{Prgomet, Mateo and Rey, Martin P. and Andersson, Eric P. and Segovia Otero, Alvaro and Agertz, Oscar and Renaud, Florent and Pontzen, Andrew and Read, Justin I.}},
  issn         = {{0035-8711}},
  keywords     = {{galaxies: Dwarf; galaxies: Evolution; galaxies: Formation; methods: Numerical}},
  language     = {{eng}},
  month        = {{06}},
  number       = {{2}},
  pages        = {{2326--2334}},
  publisher    = {{Oxford University Press}},
  series       = {{Monthly Notices of the Royal Astronomical Society}},
  title        = {{EDGE : The sensitivity of ultra-faint dwarfs to a metallicity-dependent initial mass function}},
  url          = {{http://dx.doi.org/10.1093/mnras/stac1074}},
  doi          = {{10.1093/mnras/stac1074}},
  volume       = {{513}},
  year         = {{2022}},
}