Feedback regulated turbulence, magnetic fields, and star formation rates in galactic disks

Chang Goo Kim, Eve Charis Ostriker

Research output: Contribution to journalArticle

Abstract

We use three-dimensional magnetohydrodynamic (MHD) simulations to investigate the quasi-equilibrium states of galactic disks regulated by star formation feedback. We incorporate effects from massive-star feedback via time-varying heating rates and supernova (SN) explosions. We find that the disks in our simulations rapidly approach a quasi-steady state that satisfies vertical dynamical equilibrium. The star formation rate (SFR) surface density self-adjusts to provide the total momentum flux (pressure) in the vertical direction that matches the weight of the gas. We quantify feedback efficiency by measuring feedback yields, η c≡ P c/ΣSFR (in suitable units), for each pressure component. The turbulent and thermal feedback yields are the same for HD and MHD simulations, ηth ~ 1 and ηturb ~ 4, consistent with the theoretical expectations. In MHD simulations, turbulent magnetic fields are rapidly generated by turbulence, and saturate at a level corresponding to ηmag,t ~ 1. The presence of magnetic fields enhances the total feedback yield and therefore reduces the SFR, since the same vertical support can be supplied at a smaller SFR. We suggest further numerical calibrations and observational tests in terms of the feedback yields.

Original languageEnglish (US)
Pages (from-to)38-41
Number of pages4
JournalProceedings of the International Astronomical Union
Volume11
Issue numberS315
DOIs
StatePublished - Aug 1 2015

All Science Journal Classification (ASJC) codes

  • Medicine (miscellaneous)
  • Astronomy and Astrophysics
  • Nutrition and Dietetics
  • Public Health, Environmental and Occupational Health
  • Space and Planetary Science

Keywords

  • Galaxies: ISM
  • Galaxies: Magnetic fields
  • Galaxies: Star formation
  • MHD
  • Methods: Numerical
  • Turbulence

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