Dwarf galaxies in CDM, WDM, and SIDM: Disentangling baryons and dark matter physics

Alex Fitts, Michael Boylan-Kolchin*, Brandon Bozek, James S. Bullock, Andrew Graus, Victor Robles, Philip F. Hopkins, Kareem El-Badry, Shea Garrison-Kimmel, Claude André Faucher-Giguère, Andrew Wetzel, Dušan Kereš

*Corresponding author for this work

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

We present a suite of FIRE-2 cosmological zoom-in simulations of isolated field dwarf galaxies, all with masses of Mhalo ≈ 1010 M at z = 0, across a range of dark matter models. For the first time, we compare how both self-interacting dark matter (SIDM) and/or warm dark matter (WDM) models affect the assembly histories as well as the central density structure in fully hydrodynamical simulations of dwarfs. Dwarfs with smaller stellar half-mass radii (r1/2 < 500 pc) have lower σ/Vmax ratios, reinforcing the idea that smaller dwarfs may reside in haloes that are more massive than is naively expected. The majority of dwarfs simulated with self-interactions actually experience contraction of their inner density profiles with the addition of baryons relative to the cores produced in dark-matter-only runs, though the simulated dwarfs are always less centrally dense than in CDM. The V1/2–r1/2 relation across all simulations is generally consistent with observations of Local Field dwarfs, though compact objects such as Tucana provide a unique challenge. Overall, the inclusion of baryons substantially reduces any distinct signatures of dark matter physics in the observable properties of dwarf galaxies. Spatially resolved rotation curves in the central regions (<400 pc) of small dwarfs could provide a way to distinguish between CDM, WDM, and SIDM, however: at the masses probed in this simulation suite, cored density profiles in dwarfs with small r1/2 values can only originate from dark matter self-interactions.

Original languageEnglish (US)
Pages (from-to)962-977
Number of pages16
JournalMonthly Notices of the Royal Astronomical Society
Volume490
Issue number1
DOIs
StatePublished - Jan 1 2019

Keywords

  • Dark matter
  • Galaxies: dwarf
  • Galaxies: evolution
  • Galaxies: formation
  • Galaxies: star formation
  • Galaxies: structure

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Fitts, A., Boylan-Kolchin, M., Bozek, B., Bullock, J. S., Graus, A., Robles, V., Hopkins, P. F., El-Badry, K., Garrison-Kimmel, S., Faucher-Giguère, C. A., Wetzel, A., & Kereš, D. (2019). Dwarf galaxies in CDM, WDM, and SIDM: Disentangling baryons and dark matter physics. Monthly Notices of the Royal Astronomical Society, 490(1), 962-977. https://doi.org/10.1093/mnras/stz2613