Critical Kahler toric metrics for the invariant first eigenvalue

In [LS], it is shown shown that the first eigenvalue of the Laplacian restricted to the space of invariant functions on a toric K\"ahler manifold (i.e. $\lambda_1^\mathbb{T}$, the invariant first eigenvalue) is an unbounded function of the toric K\"ahler metric. In this note we show that, seen as a function on the space of toric K\"ahler metrics on a fixed toric manifold, $\lambda_1^\mathbb{T}$ admits no analytic critical points. We also show that on $S^2$, the first eigenvalue of the Laplacian restricted to the space of $S^1$-equivariant functions of any given integer weight admits no critical points.