Convective quenching of field reversals in accretion disc dynamos

Matthew S.B. Coleman, Evan Yerger, Omer Blaes, Greg Salvesen, Shigenobu Hirose

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Vertically stratified shearing box simulations of magnetorotational turbulence commonly exhibit a so-called butterfly diagram of quasi-periodic azimuthal field reversals. However, in the presence of hydrodynamic convection, field reversals no longer occur. Instead, the azimuthal field strength fluctuates quasi-periodically while maintaining the same polarity, which can either be symmetric or antisymmetric about the disc mid-plane. Using data from the simulations of Hirose et al., we demonstrate that the lack of field reversals in the presence of convection is due to hydrodynamic mixing of magnetic field from the more strongly magnetized upper layers into the mid-plane, which then annihilate field reversals that are starting there. Our convective simulations differ in several respects from those reported in previous work by others, in which stronger magnetization likely plays a more important role than convection.

Original languageEnglish
Pages (from-to)2625-2635
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Volume467
Issue number3
DOIs
StatePublished - 1 Jun 2017

Keywords

  • Accretion
  • Accretion discs
  • Convection
  • Dynamo
  • MHD
  • Stars: dwarf novae
  • Turbulence

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