The effect of poloidal magnetic field and helicity injection on a breakout CME

TL;DR

This study uses 2.5D MHD simulations to explore how background magnetic fields and helicity injection influence CME initiation, revealing that stronger poloidal fields suppress eruptions and helicity growth rate is key to eruption likelihood.

Contribution

It introduces a numerical simulation approach to analyze the impact of background magnetic fields and helicity injection on CME eruptions within the breakout model.

Findings

Stronger background poloidal magnetic fields constrain CME eruptions.

Growth rate of net current helicity determines eruption likelihood.

Different magnetic scenarios show varied CME eruption outcomes.

Abstract

Coronal mass ejections (CMEs), as crucial drivers of space weather, necessitate a comprehensive understanding of their initiation and evolution in the solar corona, in order to better predict their propagation. Solar Cycle 24 exhibited lower sunspot numbers compared to Solar Cycle 23, along with a decrease in the heliospheric magnetic pressure. Consequently, a higher frequency of weak CMEs was observed during Solar Cycle 24. Forecasting CMEs is vital, and various methods, primarily involving the study of the global magnetic parameters using datasets like Space-weather Helioseismic and Magnetic Imager Active Region Patches (SHARP), have been employed in earlier works. In this study, we perform numerical simulations of CMEs within a magnetohydrodynamics framework using Message Passing Interface - Adaptive Mesh Refinement Versatile Advection Code (MPI-AMRVAC) in 2.5 dimensions. By employing the breakout model for CME initiation, we introduce a multipolar magnetic field configuration within a background bipolar magnetic field, inducing shear to trigger the CME eruption. Our investigation focuses on understanding the impact of the background global magnetic field on CME eruptions. Furthermore, we analyze the evolution of various global magnetic parameters in distinct scenarios (failed eruption, single eruption, multiple eruptions) resulting from varying amounts of helicity injection in the form of shear at the base of the magnetic arcade system. Our findings reveal that an increase in the strength of the background poloidal magnetic field constrains CME eruptions. Furthermore, we establish that the growth rate of absolute net current helicity is the crucial factor that determines the likelihood of CME eruptions.