On Braverman-Kazhdan's asymptotic Hecke algebra for inner forms of $\mathrm{GL}_n$

Abstract

We study Braverman-Kazhdan's asymptotic Hecke algebra $\mathcal{J}(G)$ for inner forms $G$ of $p$-adic $\mathrm{GL}_n$. We show that $\mathcal{J}(G)$ and the property for a $G$-representation to extend to a $\mathcal{J}(G)$-module are defined over $\overline{\mathbb{Q}_\ell}$, and hence make sense in the context of the categorical local Langlands correspondence. We show a rudimentary form of compatibility with Hecke operators, allowing us discuss stalks of sheaves on $\mathrm{Bun}_n$ corresponding to the trivial vector bundles on the stack of $L$-parameters, in particular the Whittaker sheaf, in terms of $\mathcal{J}(\mathrm{GL}_n)$-modules. We provide explicit formulas in terms of reductive centralizer of $L$-parameters for many functions in $\mathcal{J}(G)$, and show that $\mathcal{J}(G)$ has the same Hochschild homology as $C_c^\infty(G)$, and that the Kazhdan-Lusztig bijection appears in the isomorphism. We proceed via Bushnell-Kutzko and Sécherre-Stevens types, generalizing a theorem of Suzuki for $\mathrm{GL}_n$ for which we provide a proof.