Angular momentum transport by magnetoconvection and the magnetic modulation of the solar differential rotation

Abstract

In order to explain the variance of the solar rotation law during the activity minima and maxima, the angular momentum transport by rotating magnetoconvection is simulated in a convective box penetrated by an inclined azimuthal magnetic field. Turbulence-induced kinetic and magnetic stresses { and} the Lorentz force of the large-scale magnetic background field are the basic transporters of angular momentum. Without rotation, the sign of the magnetic stresses naturally depends on the signs of the field components as positive (negative) $B_{\theta }{B}_{\varphi }$ transport the angular momentum poleward (equatorward). For fast enough rotation, however, the turbulence-originated Reynolds stresses start to dominate the transport of the angular momentum flux. The simulations show that positive ratios of the two meridional magnetic field components to the azimuthal field reduce the inward radial as well as the equatorward latitudinal transport,%by the rotating magnetoconvection which result from hydrodynamic calculations. Only for $B_{\theta }{B}_{\varphi }>0$ (generated by solar-type rotation laws with an accelerated equator) does the magnetic-influenced rotation at the solar surface prove to be flatter than the nonmagnetic profile together with the observed slight spin-down of the equator. The latter phenomenon does not appear for antisolar rotation with polar vortex as well as for rotation laws with prevailing radial shear.

arXiv comment10 pages

References in corpus (21)

• Global-Scale Turbulent Convection and Magnetic Dynamo Action in the Solar Envelope
• Dynamo Action in the Solar Convection Zone and Tachocline: Pumping and Organization of Toroidal Fields
• Changes in Solar Dynamics from 1995 to 2002
• Meridional Circulation in Solar and Stellar Convection Zones
• Grand Minima and Equatorward Propagation in a Cycling Stellar Convective Dynamo
• Magnetoconvection and dynamo coefficients: II. Field-direction dependent pumping of magnetic field
• Magnetically controlled stellar differential rotation near the transition from solar to anti-solar profiles
• Alpha effect and turbulent diffusion from convection
• Multiple dynamo modes as a mechanism for long-term solar activity variations
• Magnetoconvection and dynamo coefficients: Dependence of the alpha-effect on rotation and magnetic field
• Local models of stellar convection: Reynolds stresses and turbulent heat transport
• Detection of negative effective magnetic pressure instability in turbulence simulations
• Turbulent transport coefficients in spherical wedge dynamo simulations of solar-like stars
• Dynamo cycles in global convection simulations of solar-like stars
• Convection-driven spherical shell dynamos at varying Prandtl numbers
• Negative effective magnetic pressure in turbulent convection
• A Relationship between the Solar Rotation and Activity Analysed by Tracing Sunspot Groups
• Magnetic and rotational quenching of the $\Lambda$ effect
• Antisolar differential rotation of slowly rotating cool stars
• Suppression of the large-scale Lorentz force by turbulence
• The turbulent pressure of magnetoconvection for slow and rapid rotation