Scattering of p-Modes by a thin magnetic flux tube

There is strong observational evidence for solar p-modes being scattered by sunspots. Understanding and comparing phase shifts or travel time delays of scattered waves can present an opportunity to deduce the subsurface structure of sunspots from the observations of p-modes. We study the scattering of acoustic waves by magnetic flux tubes embedded in the stratified atmosphere, taking into account magnetic field perturbations. For this purpose, we solve a set of linearized MHD equations using the Born approximation approach. It is shown that convergence of the magnetic field may substantially affect the phase shifts of the scattered waves.