  We consider MHD waves as a heating source of cool cores of galaxy clusters.
In particular, we focus on transverse waves (Alfven waves), because they can
propagate a longer distance than longitudinal waves (sound waves). Using MHD
simulations, we found that the transverse waves can stably heat a cool core if
the wave period is large enough (>~ 10^8 yr). Moreover, the longitudinal waves
that are created as a by-product of the nonlinear evolution of the transverse
waves could be observed as the 'ripples' found in cool cores.
