# Influence of photospheric magnetic conditions on the catastrophic behaviors of flux ropes in active regions

## TL;DR

This study uses 2.5D MHD simulations to explore how photospheric magnetic flux distributions influence the occurrence of catastrophic eruptions of flux ropes in active regions, revealing that specific photospheric conditions are crucial for catastrophe.

## Contribution

It demonstrates that photospheric magnetic flux distribution significantly affects flux rope catastrophe, expanding understanding beyond the background field topology.

## Key findings

- Catastrophe occurs only with certain flux concentrations near the polarity inversion line.
- Partially open and fully closed configurations can both exhibit catastrophe under specific conditions.
- Photospheric flux distribution is a key factor in flux rope eruption behavior.

## Abstract

Since only the magnetic conditions at the photosphere can be routinely observed in current observations, it is of great significance to find out the influences of photospheric magnetic conditions on solar eruptive activities. Previous studies about catastrophe indicated that the magnetic system consisting of a flux rope in a partially open bipolar field is subject to catastrophe, but not if the bipolar field is completely closed under the same specified photospheric conditions. In order to investigate the influence of the photospheric magnetic conditions on the catastrophic behavior of this system, we expand upon the 2.5 dimensional ideal magnetohydrodynamic (MHD) model in Cartesian coordinates to simulate the evolution of the equilibrium states of the system under different photospheric flux distributions. Our simulation results reveal that a catastrophe occurs only when the photospheric flux is not concentrated too much toward the polarity inversion line and the source regions of the bipolar field are not too weak; otherwise no catastrophe occurs. As a result, under certain photospheric conditions, a catastrophe could take place in a completely closed configuration whereas it ceases to exist in a partially open configuration. This indicates that whether the background field is completely closed or partially open is not the only necessary condition for the existence of catastrophe, and that the photospheric conditions also play a crucial role in the catastrophic behavior of the flux rope system.