The non-existence of nonnegative finite energy solutions to V 1/m(x) -& UDelta;V (x) - |x|& USigma;V(x) + m- 1 = 0, x & ISIN; RN, with m > 1, & USigma; > 0, and N > 1, is proven for & USigma; sufficiently large. More precisely, in dimension N > 4, the optimal lower bound on & USigma; for non-existence is identified, namely & USigma; > & USigma;c := 2(m- 1)(N- 1) , 3m + 1 while, in dimensions N & ISIN; {1, 2, 3}, the lower bound derived on & USigma; improves previous ones already established in the literature. A by-product of this result is the non-existence of nonnegative compactly supported separate variable solutions to a porous medium equation with spatially dependent superlinear source.(C) 2022 Elsevier Masson SAS. All rights reserved.