Stellar feedback strongly alters the amplification and morphology of galactic magnetic fields

Kung Yi Su, Christopher C. Hayward, Philip F. Hopkins, Eliot Quataert, Claude André Faucher-Giguère, Dušan Kereš

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

Using high-resolution magnetohydrodynamic simulations of idealized, non-cosmological galaxies, we investigate how cooling, star formation and stellar feedback affect galactic magnetic fields. We find that the amplification histories, saturation values and morphologies of the magnetic fields vary considerably depending on the baryonic physics employed, primarily because of differences in the gas density distribution. In particular, adiabatic runs and runs with a subgrid (effective equation of state) stellar feedback model yield lower saturation values and morphologies that exhibit greater large-scale order compared with runs that adopt explicit stellar feedback and runs with cooling and star formation but no feedback. The discrepancies mostly lie in gas denser than the galactic average, which requires cooling and explicit fragmentation to capture. Independent of the baryonic physics included, the magnetic field strength scales with gas density as B ∞ n2/3, suggesting isotropic flux freezing or equipartition between the magnetic and gravitational energies during the field amplification. We conclude that accurate treatments of cooling, star formation and stellar feedback are crucial for obtaining the correct magnetic field strength and morphology in dense gas, which, in turn, is essential for properly modelling other physical processes that depend on the magnetic field, such as cosmic ray feedback.

Original languageEnglish (US)
Pages (from-to)L111-L115
JournalMonthly Notices of the Royal Astronomical Society: Letters
Volume473
Issue number1
DOIs
StatePublished - Jan 1 2018
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Galaxy: evolution
  • ISM: jets and outflows
  • ISM: structure
  • MHD
  • Methods: numerical

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