Interplay between Alfv��n and magnetosonic waves in compressible magnetohydrodynamics turbulence

Using spatio-temporal spectra we show direct evidence of excitation of magnetosonic and Alfv��n waves in three-dimensional compressible magnetohydrodynamic turbulence at small Mach numbers. For the plasma pressure dominated regime, or high $��$ regime (with $��$ the ratio between fluid and magnetic pressure), and for the magnetic pressure dominated regime, or low $��$ regime, we study magnetic field fluctuations parallel and perpendicular to a guide magnetic field $\textbf{B}_0$. In the low $��$ case we find excitation of compressible and incompressible fluctuations, with a transfer of energy towards Alfv��nic modes and to a lesser extent towards magnetosonic modes. In particular, we find signatures of the presence of fast magnetosonic waves in a scenario compatible with that of weak turbulence. In the high $��$ case, fast and slow magnetosonic waves are present, with no clear trace of Alfv��n waves, and a significant part of the energy is carried by two-dimensional turbulent eddies.