Moduli spaces of abstract and embedded Kummer varieties

Abstract: In this paper, we investigate the construction of two moduli stacks of Kummer varieties. The first one is the stack $\mathcal K<sup>{\text{abs}}_g$ of abstract Kummer varieties and the second one is the stack $\mathcal K<sup>{\text{em}}_g$ of embedded Kummer varieties. We will prove that $\mathcal K<sup>{\text{abs}}_g$ is a Deligne-Mumford stack and its coarse moduli space is isomorphic to $\boldsymbol A_g$, the coarse moduli space of principally polarized abelian varieties of dimension $g$. On the other hand we give a modular family $\mathcal W_g\to U$ of embedded Kummer varieties embedded in $$\mathbb P^{{2^{g-1}\times\mathbb}} P<sup>{2<sup>g-1}$$, meaning that every geometric fiber of this family is an embedded Kummer variety and every isomorphic class of such varieties appears at least once as the class of a fiber. As a consequence, we construct the coarse moduli space $\boldsymbol{\mathsf K}<sup>{\text{em}}_2$ of embedded Kummer surfaces and prove that it is obtained from $\boldsymbol A_2$ by contracting a particular curve inside this space. We conjecture that this is a general fact: $\boldsymbol{\mathsf K}<sup>{\text{em}}_g$ could be obtained from $\boldsymbol A_g$ via a contraction for all $g&gt;1$.