  We investigate the influence of magnons on the temperature-dependence and the
anisotropy of the spin-orbit torque (SOT). For this purpose we use 3rd order
perturbation theory in the framework of the Keldysh formalism in order to
derive suitable equations to compute the magnonic SOT. We find several
contributions to the magnonic SOT, which depend differently on the spin-wave
stiffness $\mathcal{A}$ and on the temperature $T$, with the dominating
contribution scaling like $T^{2}/\mathcal{A}^{2}$. Based on this formalism we
compute the magnonic SOT in the ferromagnetic Rashba model. For large Rashba
parameters the magnonic SOT is strongly anisotropic and for small quasiparticle
broadening it may become larger than the non-magnonic SOT.
