Presentation #407.03 in the session Understanding Solar Eruptions Using Data-driven Models and Multi-height Observations of the Solar Atmosphere I.
We present results from data inspired MURaM simulations of the formation of collisional polarity inversion lines, the buildup of free energy and release in the form of flares. The simulation includes the essential physics to synthesize thermal emission ranging from the visible spectrum in the photosphere to EUV and soft X-ray from transition region and corona. In the numerical setup we start with a bipolar sunspot configuration and set the spots on a collision course by imposing the appropriate velocity field at the footpoints in the sub photospheric boundary. We vary parameters such as collision speed, collision distance and spot coherence during the collision. We find the strongest flares (lower M class) for the setups with the closest spot encounters. While spot dispersal during the collision (and therefore a longer polarity inversion line) leads to the formation of a strongly twisted pre-eruption magnetic flux rope that carries mass in dipped field lines, more coherent spots delay the formation of such flux rope to the time of eruption. We discuss how multi-height chromospheric spectro-polarimetric observations could diagnose the structure of the pre-eruption magnetic configuration.