The derived $\infty$-category of Cartier Modules

TL;DR

This paper develops a new framework for generalized Cartier modules within the context of $alculus categories, establishing their properties, monadicity, and connections to derived categories and perverse t-structures, extending classical notions in algebraic geometry.

Contribution

It introduces the $ategory$ of generalized Cartier modules as a lax equalizer, proves its monadicity, and constructs a perverse t-structure on derived categories of Cartier modules over schemes.

Findings

The $ategory$ of Cartier modules is a lax equalizer of an endofunctor and the identity.

Under certain conditions, this category is monadic over the base category.

A perverse t-structure is constructed on the derived category of Cartier modules for schemes over $_p$.

Abstract

For an endofunctor $F\colon\mathcal{C}\to\mathcal{C}$ on an ($\infty$-)category $\mathcal{C}$ we define the $\infty$-category $\operatorname{Cart}(\mathcal{C},F)$ of generalized Cartier modules as the lax equalizer of $F$ and the identity. This generalizes the notion of Cartier modules on $\mathbb{F}_p$-schemes considered in the literature. We show that in favorable cases $\operatorname{Cart}(\mathcal{C},F)$ is monadic over $\mathcal{C}$. If $\mathcal{A}$ is a Grothendieck abelian category and $F\colon\mathcal{A}\to\mathcal{A}$ is an exact and colimit-preserving endofunctor, we use this fact to construct an equivalence $\mathcal{D}(\operatorname{Cart}(\mathcal{A},F)) \simeq \operatorname{Cart}(\mathcal{D}(\mathcal{A}),\mathcal{D}(F))$ of stable $\infty$-categories. We use this equivalence to construct a perverse t-structure on $\mathcal{D}(\operatorname{Cart}(\operatorname{Mod}(X), F_*))$ for any Noetherian $\mathbb{F}_p$-scheme $X$ with absolute Frobenius $F$. If $F$ is finite, this coincides with the perverse t-structure constructed by Baudin.