Helioseismic analysis of the solar flare-induced sunquake of 2005 January 15 – II. A magnetoseismic study

On 2005 January 15, the active region AR10720 produced an X1.2 solar flare that induced high levels of seismicity in the photospheric layers. The seismic source was detected using helioseismic holography and analysed in detail in Paper I. Egression power maps at 6 mHz, with a 2 mHz bandwidth, revealed a compact acoustic source, strongly correlated with the footpoints of the coronal loop that hosted the flare. We present a magnetosiesmic study of this active region to understand, for the first time, the magnetic topological structure of a coronal field that hosts an acoustically active solar flare. The accompanying analysis attempts to answer questions such as: can the magnetic field act as a barrier and prevent seismic waves from spreading away from the focus of the sunquake? What is the most efficient magnetic structure that would facilitate the development of a strong seismic source in the photosphere?