B-fields do not suppress star formation in low metallicity dwarf galaxies

David J. Whitworth, Rowan J. Smith, Ralf S. Klessen, Mordecai-Mark Mac Low, Simon C. O. Glover, Robin Tress, Rüdiger Pakmor, Juan D. Soler

Research output: Contribution to journalArticlepeer-review


Many studies have looked at the impact of magnetic fields on star formation in molecular clouds and Milky Way like galaxies, concluding that the field suppresses star formation. However, most of these studies are based on fully developed fields that have reached the saturation level, with little work on investigating how the growth phase of a primordial field affects star formation in low metallicity
environments. In this paper, we investigate the impact of the growth phase of a primordial field on low metallicity dwarf galaxies. We perform high-resolution arepo simulations of 5 isolated dwarf galaxies. Two models are hydrodynamical, two start with a primordial B-field of 10−6µG, and one with a saturated B-field of 10−2µG. All models include a non-equilibrium, time-dependent chemical network that includes the effects of gas shielding from the ambient UV field. Sink particles form directly from the gravitational collapse of gas and are treated as star-forming clumps that can accrete gas. We vary the metallicity, UV-field, and cosmic ray ionization rate between 1% and 10% of solar values. We find that the magnetic field has little impact on the star formation rate, which is in tension with previously published results. We show that an increase in the mass fractions of both molecular hydrogen and cold gas, along with changes in the perpendicular gas velocity dispersion’s and the B-field acting in the weak-field model overcomes the expected suppression in star formation.
Original languageEnglish
JournalRoyal Astronomical Society. Monthly Notices
Publication statusAccepted/In press - 5 Jan 2023


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