Suppression of amplitude of 5-min oscillations in sunspots due to the lack of acoustic sources

Acoustic waves on the Sun are excited by subsurface turbulent convection. However, in sunspots the excitation is suppressed because strong magnetic field inhibits convection. We use 3D simulations of acoustic waves to investigate how the suppression of excitation sources affects the distribution of acoustic power in sunspot regions. These simulations show that the amplitude of acoustic oscillations is approximately 4 times lower in the region with suppressed sources in comparison with the quiet Sun. This is in good agreement with observations of 5-min oscillations in sunspots. Hence, the observed reduced oscillation power in sunspots can be explained almost entirely by the suppression of acoustic sources in sunspot areas. These results challenge the current paradigm that the extinction of 5-min oscillations in sunspots is caused by absorption and transformation into other types of MHD waves in sunspot magnetic fields.