The role of magnetic fields in starburst galaxies as revealed by OH megamasers

James McBride, Eliot Quataert, Carl Heiles, Amber Bauermeister

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

We present estimates of magnetic field strengths in the interstellar media of starburst galaxies derived from measurements of Zeeman splitting associated with OH megamasers. The results for eight galaxies with Zeeman detections suggest that the magnetic energy density in the interstellar medium of starburst galaxies is comparable to their hydrostatic gas pressure, as in the Milky Way. We discuss the significant uncertainties in this conclusion, and possible measurements that could reduce these uncertainties. We also compare the Zeeman splitting derived magnetic field estimates to magnetic field strengths estimated using synchrotron fluxes and assuming that the magnetic field and cosmic rays have comparable energy densities, known as the "minimum energy" argument. We find that the minimum energy argument systematically underestimates magnetic fields in starburst galaxies, and that the conditions that would be required to produce agreement between the minimum energy estimate and the Zeeman derived estimate of interstellar medium magnetic fields are implausible. The conclusion that magnetic fields in starburst galaxies exceed the minimum energy magnetic fields is consistent with starburst galaxies adhering to the linearity of the far-infrared-radio correlation.

Original languageEnglish (US)
Article number182
JournalAstrophysical Journal
Volume780
Issue number2
DOIs
StatePublished - Jan 10 2014

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • galaxies: ISM
  • galaxies: magnetic fields
  • galaxies: starburst
  • infrared: galaxies
  • masers Online-only material: color figures

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