Abstract We investigate the oscillatory behaviour of the footpoints of twisted magnetic flux tubes in the solar photosphere. We identify the dominant magnetohydrodynamic (MHD) wave modes present in these waveguides and assess their role in energy transport. Using vector magnetograms from the Solar Dynamics Observatory/Helioseismic and Magnetic Imager Space-weather HMI Active Region Patches (SDO/HMI SHARP) series of active region 11158, the footpoints of twisted flux tubes are identified as convex local maxima of the Integrated Average Current Deviation (IACD) field, which highlights regions of enhanced magnetic twist and current concentration. To study the waves propagating in these structures, we apply the Spectral Proper Orthogonal Decomposition (SPOD) method, which separates complex spatio-temporal data into oscillatory patterns and their characteristic frequencies. Our analysis shows that the footpoints of the twisted flux tubes support both kink and sausage MHD modes, with oscillations detected across multiple diagnostics, including IACD, the vertical magnetic field, and the vertical Poynting flux. The coexistence of these modes suggests nonlinear interactions or mode coupling within the twisted magnetic structures. These twisted flux tubes act as magnetic waveguides that modulate the vertical transport of energy between the photosphere and higher atmospheric layers. The inferred upward Poynting fluxes (10^5 10 5 – 10^6~W\, m^-2 10 6 W m − 2) indicate that such twisted magnetic features may contribute to localised chromospheric heating.
Alanezy et al. (2026) studied this question.