5. Moduli of Kähler K3 surfaces [04YS]
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5. Moduli of Kähler K3 surfaces
It is known (cf., [Tod80], [Looi81], [KT87]) that the moduli space of all Einstein metrics on a Kähler K3 surfaces (including orbifold-metrics) has again a structure of the locally Riemannian symmetric space:
which we denote by . An enriched version encoding also complex structures of the K3 surfaces is
Roughly speaking, this is a union of Kähler cones of ADE K3 surfaces with marking of the minimal resolutions.
Thus we can again compare a Satake compactification of with the Gromov-Hausdorff compactification. Inside the Satake compactification for the adjoint representation, we consider an open locus (a partial compactification of ) where denotes the -dimensional boundary stratum corresponding to an isotropic rational line in , with primitive integral generator , which are unique up to . Then for each point in strata , we consider the marked (possibly ADE) K3 surface with period . Then it is known that there is an elliptic K3 surface structure on with the fiber class . Then we define as its base biholomorphic to with the McLean metric, which only depends on . Similarly to the projective case Theorem 4.4, [OO] proves that for non-algebraic situation:
Theorem 5.1.
The map
given above is continuous. Here, we put the Gromov-Hausdorff topology for the right hand side.
In [OO], we further explicitly define an extension to the whole Satake compactification , and conjecture that this is still continuous with respect to the Gromov-Hausdorff topology. For the boundary strata other than , we assign flat tori modulo -multiplication. We show that restricted to the closure of the locus which parametrizes modulo , that includes those boundary strata, is continuous. Furthermore, we also prove the restriction of to the closure of is continuous by using Weierstrass models.