Optimal Liouville theorem for a semilinear Ornstein-Uhlenbeck equation

The question of triviality of solutions of the semilinear Ornstein-Uhlenbeck equation, $$\Delta w-\frac{1}{2} \langle x,\nabla w\rangle-\frac{\lambda}{p-1}w+|w|^{p-1}w=0,$$ is considered. It is shown, that if $p>1$ is Sobolev subcritical or critical and $\lambda\leq 1$, then all bounded entire solutions are constant. Moreover, in the critical case, the same conclusion holds in the subclass of radial solutions provided that $n\geq 4$ and $\lambda \in \left[\frac{3 n}{2(n-1)},2\right]$.