Abstract
At the Earth’s magnetopause, flux tubes observed by the Magnetospheric
Multiscale (MMS) spacecraft in “entangled” pairs have been interpreted
as a precursory stage to the formation of a new pair of flux ropes by
magnetic reconnection, of which one reconnected rope joins the
magnetosphere. Understanding the connectivity of these tubes before and
after the entanglement is essential to understanding the transport of
particles and energy between the magnetosphere and the solar wind. In
this paper, we use a three-dimensional Hall MHD model to simulate the
interaction of two entangled flux tubes in the ambient plasma. Four
types of interactions are simulated: Two types of magnetic field
geometry (flux tube-flux tube, and flux rope-flux rope) are tested
separately, each under two different boundary conditions that drive the
interaction. With one type of boundary condition, magnetic reconnection
transforms the two tubes/ropes into new pairs. The process is performed
under plasma conditions comparable to those of such events identified in
recent MMS observations. The detailed 3-D evolution is shown at
representative stages, with key parameters shown across the entanglement
interface. The shape of the central current sheet and evolution of
magnetic field curvature are also discussed. Our study supports the
feasibility of reconnection between entangled flux tubes, recognizes the
importance of ambient plasma conditions for the completion of such
processes, and quantifies how such structures evolve to modify the solar
wind-geomagnetic field interaction. In addition, this model is
applicable to flux rope interactions in the solar corona.