Cycle carac\'eristique pour les D-modules coadmissibles sur une courbe formelle

Abstract

Let $\mathfrak{X}$ be a formal smooth quasi-compact curve over a complete discrete valuation ring of mixed characteristic. We consider over $\mathfrak{X}$ the sheaves of differential operators $\widehat{\mathcal{D}}^{(0)}_{\mathfrak{X}, k , \mathbb{Q}}$ with a congruence level $k \in \mathbb{N}$ and their projective limit $\mathcal{D}_{\mathfrak{X}, \infty} = \varprojlim_k \widehat{\mathcal{D}}^{(0)}_{\mathfrak{X}, k , \mathbb{Q}}$. In this article, we define a characteristic variety for coadmissible $\mathcal{D}_{\mathfrak{X}, \infty}$-modules as a closed subset of the cotangent space $T^*\mathfrak{X}$. For this purpose, we introduce a microlocalization sheaf of $\mathcal{D}_{\mathfrak{X}, \infty}$ in which the derivation is locally invertible. We deduce a notion of "sub-holonomicity" for coadmissible $\mathcal{D}_{\mathfrak{X}, \infty}$-modules which is equivalent to being generically an integrable connection. Finally, we associate characteristic cycles to sub-holonomic modules proving that the latter are of finite length.