Probing the internal solar magnetic field through g modes

Abstract

The observation of g-mode candidates by the Solar and Heliospheric Observatory (SOHO) mission opens the possibility of probing the internal structure of the solar radiative zone (RZ) and the solar core more directly than possible via the use of the p-mode helioseismology data. We study the effect of rotation and RZ magnetic fields on g-mode frequencies. Using a self-consistent static magnetohydrodynamics magnetic field model, we show that a 1 per cent g-mode frequency shift with respect to the Solar Seismic Model (SSEM) prediction, currently hinted in the Global Oscillation at Low Frequencies (GOLF) data, can be obtained for magnetic fields as low as 300 kG, for current measured modes of radial order n = -20. On the other hand, we also argue that a similar shift for the case of the low-order g-mode candidate (l = 2, n = -3) frequencies cannot result from rotation effects nor from central magnetic fields, unless these exceed 8 MG.