Global Ricci curvature behaviour for the Kähler-Ricci flow with finite time singularities

Abstract

We consider the Kähler-Ricci flow ${(X,\omega (t\left)\right)}_{t\in [0,T)}$ on a compact manifold where the time of singularity, T, is finite. We assume the existence of a holomorphic map from the Kähler manifold X to some analytic variety Y which admits a Kähler metric on a neighbourhood of the image of X and that the pullback of this metric yields the limiting cohomology class along the flow. This is satisfied, for instance, by the assumption that the initial cohomology class is rational, i.e., $\left[{\omega }_0\right]\in H^{1,1}(X,Q)$. Under these assumptions we prove an $L^4$-spacetime estimate on the behaviour of the Ricci curvature and that the Riemannian curvature is Type I with respect to the $L^2$-norm.