We consider the problem (P) u_t + (−∆)^ s u = λ \frac{u^p }{δ^{2s} (x) } in Ω T ≡ Ω × (0, T), u(x, 0) = u 0 (x) in Ω, u = 0 in (IR N \ Ω) × (0, T), where Ω ⊂ IR^ N is a bounded regular domain (in the sense that ∂Ω is of class C^{ 0,1}), δ(x) = dist(x, ∂Ω), 0 < s < 1, p > 0, λ > 0. The purpose of this work is twofold. First We analyze the interplay between the parameters s, p and λ in order to prove the existence or the nonexistence of solution to problem (P) in a suitable sense. This extends previous similar results obtained in the local case s = 1. Second We will especially point out the differences between the local and nonlocal cases.