Curtis homomorphisms and the integral Bernstein center for GL_n

We describe two conjectures, one strictly stronger than the other, that give descriptions of the integral Bernstein center for GL_n(F) (that is, the center of the category of smooth W(k)[GL_n(F)]-modules, for F a p-adic field and k an algebraically closed field of characteristic l different from p) in terms of Galois theory. Moreover, we show that the weak version of the conjecture (for m at most n) implies the strong version of the conjecture. In a companion paper [HM] we show that the strong conjecture for n-1 implies the weak conjecture for n; thus the two papers together give an inductive proof of both conjectures. The upshot is a description of the integral Bernstein center for GL_n in purely Galois-theoretic terms; previous work of the author shows that such a description implies the conjectural "local Langlands correspondence in families" of Emerton and the author.Comment: Final accepted version. 36 pages. Note that the published version of Helm-Moss, "Converse theorems and the local Langlands correspondence in families" references an earlier version of this paper, and the section numbering has changed; in particular sections 9,10, and 11 of the referenced version correspond to sections 8,9, and 10 of the current version, respectivel

Bass Numbers of Semigroup-Graded Local Cohomology

Given a module M over a ring R which has a grading by a semigroup Q, we present a spectral sequence that computes the local cohomology of M at any Q-graded ideal I in terms of Ext modules. This method is used to obtain finiteness results for the local cohomology of graded modules over semigroup rings; in particular we prove that for a semigroup Q whose saturation is simplicial, the Bass numbers of such local cohomology modules are finite. Conversely, if the saturation of Q is not simplicial, one can find a graded ideal I and a graded R-module M whose local cohomology at I in some degree has an infinite-dimensional socle. We introduce and exploit the combinatorially defined essential set of a semigroup.Comment: 19 pages LaTeX, 1 figure (.eps) Definition 5.1 corrected; transcription error in Theorem 7.1.3 fixe

Potential automorphy over CM fields

Let $F$ be a CM number field. We prove modularity lifting theorems for regular $n$-dimensional Galois representations over $F$ without any self-duality condition. We deduce that all elliptic curves $E$ over $F$ are potentially modular, and furthermore satisfy the Sato--Tate conjecture. As an application of a different sort, we also prove the Ramanujan Conjecture for weight zero cuspidal automorphic representations for $\mathrm{GL}_2(\mathbf{A}_F)$.Comment: A number of details have been included to address the concerns of the referees. The definition of decomposed generic (Def 4.3.1) has been weakened slightly to be in line with the current version of arxiv.org/abs/1909.01898, resulting in a strengthening of a number of our theorems. This is the accepted version of the pape