A Jacquet-Langlands functor for -adic locally analytic representations
Abstract.
We study the locally analytic theory of infinite level local Shimura varieties. As a main result, we prove that in the case of a duality of local Shimura varieties, the locally analytic vectors of different period sheaves at infinite level are independent of the actions of the -adic Lie groups and of the two towers; this generalizes a result of Pan for the Lubin-Tate and Drinfeld spaces for . We apply this theory to show that the -adic Jacquet-Langlands functor of Scholze commutes with the passage to locally analytic vectors, and is compatible with central characters of Lie algebras. We also prove that the compactly supported de Rham cohomology of the two towers are isomorphic as smooth representations of .
1991 Mathematics Subject Classification:
11F77, 11G18 ,14G35, 22E501. Introduction
Let be a prime number. The main objective of this work is to give some new insights in the locally analytic incarnation of the -adic local Langlands correspondence, cf. [Bre10] [CDP14]. The objects of study in this paper are the infinite level Lubin-Tate and Drinfeld spaces (or more generally local Shimura varieties) and the locally analytic vectors for the action of the associated -adic Lie groups on different period sheaves. To motivate our main results let us recall the perfectoid geometry of the Lubin-Tate and Drinfeld spaces.
Let be a finite extension of with ring of integers , pseudo-uniformizer and residue field . Fix an algebraic closure of and let be the completion of the maximal unramified extension of with residue field . Write . Consider the group , let be the cocharacter with occurrences of and let be a formal -module over of dimension and -height . Denote by the central division algebra over with invariant . Let be the formal scheme over parametrizing deformations of the formal -module . The Lubin-Tate space of at level is the rigid generic fiber of . The space has a dual given by the Drinfeld space defined as the complement of the -rational hyperplanes of . These are particular examples of Rapoport-Zink spaces [RZ96] which are themselves special cases of local Shimura varieties [RV14] [SW20].
The spaces and are intimately related via perfectoid geometry in a very clean way: let be the Lubin-Tate space at infinite level obtained by trivializing the Tate module of the universal deformation of . It was shown in [SW13] that has a natural structure of a perfectoid space which, by construction, is a proétale -torsor over . Furthermore, a Hodge-Tate period map is constructed in loc. cit.
The image of the Hodge-Tate period map is the Drinfeld space , and the map is a proétale -torsor. When composing with the Grothendieck-Messing period map , the morphism
becomes a proétale -torsor.
Summarizing, we have a perfectoid space endowed with an action of fitting in an equivariant diagram
(1.1) |
such that:
-
•
is a -equivariant -torsor for the natural action of on .
-
•
is a -equivariant -torsor where acts on via its embedding into .
-
•
The diagram carries a suitable Weil descent over . Thus, its base change to carries an action of the Weil group .
The diagram (1.1) actually encodes the isomorphism of the Lubin-Tate and Drinfeld towers which was previously established by Fargues in [Far08] and envisioned by Faltings in [Fal02].
In particular, there is an action of on the infinite level Lubin-Tate space which makes natural the expectation that both the Jacquet-Langlands correspondence, relating and -representations, and the Langlands correspondence, relating and -representations, can be realized in different cohomologies attached to , see for example [Far08], [DLB17], [CDN20], [CDN21], [CDN23].
In [Sch18], Scholze used the diagram (1.1) to construct a -adic Jacquet-Langlands functor sending smooth admissible representations of to smooth admissible representations of . Let us be more precise; let be an admissible representation of over an artinian ring which is -power torsion. Since is a proétale -torsor the representation gives rise an étale sheaf on the rigid space . Furthermore, this étale sheaf descends to the -stack and so its cohomology carries a natural action of . The Jacquet-Langlands functor is the functor sending a smooth admissible representation of to the complex of smooth -representations over
By [Sch18, Theorem 1.1] the cohomology groups of are smooth admissible representations of over and for . In addition, [Sch18, Theorem 1.3] says that this construction satisfies a local-global compatibility for (though the main ideas should hold for general ), justifying the compatibility with a more classical Jacquet-Langlands correspondence.
One can naturally extend the Jacquet-Langlands functor to unitary Banach representations and it is not hard to see that it also preserves admissible Banach representations, see Corollary 5.3.5. On the other hand, Schneider-Teitelbaum introduced a class of admissible locally analytic representations for -adic Lie groups in [ST03]. A natural question arises:
Question 1.1.
Is there a Jacquet-Langlands functor for admissible locally analytic representations of ? If so, is it compatible with the Jacquet-Langlands functor of Banach representations?
In this paper we give a partial answer to this question, namely, that the Jacquet-Langlands functor for admissible Banach representations is compatible with the passage to locally analytic vectors, see 1.8 for a more precise statement.
In a different direction, the works of Lue Pan [Pan22a, Pan22b] studying the locally analytic vectors of perfectoid modular curves use some special sheaves of locally analytic functions at infinite level. These sheaves encode, via the localization theory of Beilinson-Bernstein on the flag variety [BB81] and the Hodge-Tate period map, many aspects of the -adic Hodge theory of Shimura varieties. In [RC23, RC24b] some of these features have been generalized to arbitrary global Shimura varieties under the name of geometric Sen theory; part of the goals of this paper is to extend the results in geometric Sen theory from the global to the local set up. It is then natural to ask what additional properties local Shimura varieties acquire after taking locally analytic vectors, in particular one can ask the following question:
Question 1.2.
Let be the infinite level Lubin-Tate space and let be its structural sheaf as a perfectoid space. Let be an affinoid perfectoid and let and be the (open) stabilizers of . Do we have an equality of locally analytic vectors
as subspaces of ? Equivalently, are the locally analytic vectors of the structural sheaf at infinite level independent of the tower?
For the case of this is proven by Pan in [Pan22b, Corollary 5.3.9] via explicit power series expansions. In this paper we prove a much more general result that holds for an arbitrary duality of local Shimura varieties and arbitrary period sheaves appearing in the affinoid charts of relative Fargues-Fontaine curves, see 1.2 for a precise statement. Then, the partial result towards 1.1 mentioned above will be a rather formal consequence of this independence of locally analytic vectors at infinite level, after applying enough technology coming from the theory of solid locally analytic representations [RJRC22, RJRC23]. We also apply this independence of locally analytic vectors to construct an equivariant isomorphism for the compactly supported de Rham cohomology between the two towers of a duality of local Shimura varieties, see 1.7.
In order to present the main results of this paper we have separated the introduction in different paragraphs, going from the general results on towers of rigid spaces, passing to the applications to local Shimura varieties, and finishing with the most specific applications to the Lubin-Tate and Drinfeld towers.
Main results
Cohomology of towers of rigid spaces
In this paragraph we explain the results of Section 5.1 about locally analytic vectors of period sheaves in towers of rigid spaces. Let be the category of perfectoid spaces and the full subcategory of perfectoid spaces in characteristic . Following [Sch22] we see and as sites endowed with the -topology. Let be the category of perfectoid spaces in characteristic endowed with a fixed pseudo-uniformizer , and with maps preserving the pseudo-uniformizer. We can define different period sheaves as follows:
-
i.
We have the structural sheaves and mapping an affinoid perfectoid to and respectively.
-
ii.
We have the tilted sheaves and mapping an affinoid perfectoid to and respectively.
-
iii.
We have the period sheaf mapping an affinoid perfectoid to where is the functor of -typical Witt vectors.
-
iv.
For a compact interval with rational ends we define the period ring mapping an affinoid perfectoid in characteristic with fixed pseudo-uniformizer to the rational localization
The period sheaves in (i)-(iii) above are standard in -adic Hodge theory. The sheaves in (iv) give rise to affinoid charts of families of Fargues-Fontaine curves as in [SW20] and [FS24].
Let be a perfectoid field in characteristic containing the -th powers roots of unit and let be a qcqs smooth rigid space over . Let be a compact -adic Lie group acting on . Let be another compact -adic Lie group and suppose we are given with an -equivariant pro-finite-étale -torsor of the diamond attached to . In particular, is endowed with an action of the -adic Lie group . The following theorem relates the locally analytic vectors of the -cohomologies of period sheaves at infinite level.
Theorem 1.3 (Theorem 5.1.1).
Let be a compact interval with rational ends. Then the -locally analytic vectors of the solid -linear representation are -locally analytic. More precisely, the natural map of solid -representations
is an equivalence.
Remark 1.1.
1.3 holds for a larger class of -modules, including and -vector bundles, see Remark 5.1.5.
As a corollary, in the case when , we prove that proétale cohomologies of qcqs rigid varieties endowed with actions of -adic Lie groups tent to be locally analytic:
Corollary 1.1 (Corollary 5.1.6).
Let be a qcqs smooth rigid space endowed with the action of a -adic Lie group . Then for a compact interval with rational ends the solid -representation is -locally analytic.
Remark 1.2.
1.1 implies that the cohomology groups of period sheaves on admit an action of the Lie algebra of obtained by derivations, we found this fact surprising since there is no finiteness or Hausdorff assumptions in the cohomology groups. This also suggests that there is a deeper structure in the period sheaves of rigid spaces that witness the locally analytic properties of their cohomologies. In a work in progress of Johannes Anschütz, Arthur-César le Bras, Peter Scholze and the second author we expect to give a conceptual explanation of these facts via the analytic prismatization.
Geometric Sen theory over local Shimura varieties
In the next paragraph we state the main results of Section 4 extending those of [Pan22a] and [RJRC22] about the Sen operators of local Shimura varieties. In order to be more precise we need to introduce some notation, we shall follow [SW20]. Let be a local Shimura datum as in Lecture XXIV of loc. cit., let be the field of definition of and the completion of the maximal unramified extension of . Let and be the algebraic flag varieties parametrizing decreasing and increasing -filtrations of the trivial -torsor respectively. We let and be the analytification of the flag varieties to adic spaces [Hub94]. For open compact subgroup we let be the local Shimura variety over at level .
Let be a finite extension where the group is split and let us fix once and for all a cocharacter representing the conjugacy class of . Let and be the parabolic subgroups parametrizing decreasing and increasing filtrations of , let and be their unipotent radicals respectively, and let be the centralizer of (eq. of ) in . We have presentations for the flag varieties and , these presentations give rise to an equivalence of -equivariant quasi-coherent sheaves on and and algebraic representations of and respectively.
Let be the Lie algebras of and the Lie algebra of the Levi quotient. We see these Lie algebras endowed with the adjoint action of and consider their corresponding -equivariant Lie algebroids and appearing in the localization theory of Beilinson-Bernstein [BB81]. We denote in the same way their pullbacks to vector bundles over the analytic flag varieties, and use similar notation for the Lie algebras of the opposite parabolic and their associated Lie algebroids in .
Let be the infinite level local Shimura variety seen as a diamond over and consider the Grothendieck-Messing and Hodge-Tate period maps
Let be the group of automorphisms of the constant -torsor over the curve, see [FS24, III.5.1]. Then is endowed with an action of for which both maps and are equivariant in a suitable sense (see Section 3 for more details).
By [SW20, Corollary 23.3.2], when is basic there is a dual local Shimura datum , an isomorphism and a -equivariant isomorphism of infinite level local Shimura varieties
that exchanges the Grothendieck-Messing and Hodge-Tate period maps (see also Proposition 3.2.3).
On the other hand, the map is a proétale -torsor. Thus, for any ind-system of -adically complete continuous representations of we can construct a -sheaf on by first constructing the -complete -sheaves via descent along and then by extending by colimits (see Definition 3.3.3). In particular, for an algebraic representation of we have automorphic local systems , and for a smooth admissible representation of over a -power torsion ring the sheaf is the étale local system considered in [Sch18] for the -adic Jacquet-Langlands functor.
Let be the local system over the local Shimura tower attached to the dual of the adjoint representation of . Let us write by for the structural sheaf of a finite level local Shimura variety and let be its cotangent bundle. We now state the first theorem concerning the computation of the geometric Sen operators of local Shimura varieties extending [RC24b, Theorem 5.2.5].
Theorem 1.4 (Theorem 4.3.1).
The geometric Sen operator of the tower in the sense of [RC23, Theorem 3.3.4] is given by the pullback along of the -equivariant map of vector bundles on
where the identification is through the opposite of the Kodaira-Spencer isomorphism, see Section 4.1. Here is the -th Hodge-Tate twist of by the -th power of the cyclotomic character.
Remark 1.3.
The previous theorem was stated for the base change of flag varieties and local Shimura varieties to . This base change can be avoided if one works without fixing a Hodge cocharacter , indeed, the flag varieties and the Hodge-Tate period maps are already defined over . Moreover, the Lie algebroids , and are also defined over , see Remark 2.5.1.
A first consequence of the computation of the geometric Sen operator is the vanishing of the higher locally analytic vectors of the structural sheaf at infinite level, as well as the computation of the arithmetic Sen operator in terms of representation theory. Let be a completed algebraically closed extension and consider the -base change of the local Shimura varieties. Let be the space of locally analytic functions of endowed with the left regular action and let be the -sheaf over obtained by descent from infinite level. We have the following theorem, analogue to Proposition 6.2.8, Corollary 6.2.12 and Theorem 6.3.5 of [RC24b].
Theorem 1.5 (Theorem 4.3.3).
Let be an open affinoid subspace admitting an étale map to a product of tori that factors as a finite composition of rational localizations and finite étale maps. Let be the pullback of , then the -cohomology
(1.2) |
sits in degree and is equal to the locally analytic vectors of . Here the completed tensor product is a filtered colimit of -completed tensor products obtained by writing as a colimit of Banach sheaves (equivalently a solid tensor product as in [AM24]).
Furthermore, the action of on by derivations kills . Thus, we have an horizontal action of on . Moreover, the space has an arithmetic Sen operator as in [RC24b, Theorem 6.3.5] given by the opposite of the derivative of the Hodge cocharacter .
Locally analytic vectors of local Shimura varieties
In this paragraph we apply 1.3 to prove the independence of locally analytic vectors for a duality of local Shimura varieties, generalizing a theorem of Pan for the Lubin-Tate tower of [Pan22b, Corollary 5.3.9]. Let be a complete algebraically closed field, we write and let be the profinite quotient of .
Let be the restriction of the structural sheaf in the -site of to the underlying topological space . Let be the subsheaf whose values in a qcqs open subspace are given by the -locally analytic sections of , namely, given by
where is the stabilizer of . We have the following corollary:
Corollary 1.2 (5.1.9).
For any -adic Lie group and any qcqs open subspace the natural map
from the derived -locally analytic vectors is an equivalence. In particular, if is basic we have an equality of subsheaves of
More generally, for basic and a compact interval with rational ends, we have an equivalence of derived solid locally analytic representations of
From now on we shall focus in the case when is basic. We will identify the and -locally analytic vectors of the structural sheaf at infinite level and simply write . We can then identify the horizontal actions of the Levi Lie algebras of 1.5. For this, we need some additional notation.
By Corollary 3.3.7 we have a natural -equivariant isomorphism of -vector bundles on
By taking locally analytic vectors we obtain an -vector bundle which we shall denote as , endowed with -equivariant isomorphisms
(1.3) |
We have the following theorem:
Theorem 1.6 (Theorem 5.1.10).
The actions of and on vanish. Furthermore, the actions of and on by derivations are identified via (1.3). In particular, the central character of the actions of and on agree under the natural isomorphism of the center of the enveloping algebras , where and are the Levi subalgebras of and respectively.
De Rham cohomology of towers of local Shimura varieties
Our next result is the comparison between compactly supported de Rham cohomologies of the two towers in a duality of local Shimura varieties. This theorem has been also independently obtained by Guido Bosco, Wiesława Nizioł and the first author. Let be a local Shimura datum with basic and let be the dual local Shimura datum. Consider the towers of rigid spaces and . We have the following theorem:
Theorem 1.7 (Theorem 5.2.2).
There is a natural -equivariant isomorphism of compactly supported de Rham cohomology groups
Remark 1.4.
1.7 should be seen as an evidence of the fact that there is a well defined analytic de Rham stack (in the sense of [RC24a]) for the infinite level Shimura variety, together with -equivariant equivalences
Indeed, as it was explained by Scholze to the second author, one can prove sufficient descent for the formation of the analytic de Rham stack to be well defined for (suitable nice) diamonds, where the previous equivalence holds as analytic stacks. It is likely that purely motivic techniques as those appearing in [Vez19] are enough to show the equivalence of the de Rham cohomologies for the two towers, see Proposition 4.5 in loc. cit.; we thanks Arthur-César le Bras for this observation.
Locally analytic Jacquet-Langlands functor in the Lubin Tate case
We finish the presentation of the main results with the principal motivation that initiated this project, that is, the -adic Jacquet-Langlands functor of the Lubin-Tate tower treated in [Sch18]. We shall keep the notation of the beginning of the introduction regarding the Lubin-Tate and Drinfeld towers. We have the following compatibility with the passage to locally analytic vectors:
Theorem 1.8 (Theorem 5.3.6).
Let be an admissible Banach representation of and let be the space of locally analytic vectors seen as a colimit of Banach spaces. Let be the proétale sheaf over constructed via descent along of the continuous representation . There is a natural equivalence of solid locally analytic -representations
Furthermore, this equivalence induces an isomorphism of cohomology groups:
As a corollary of Theorems 1.6 and 1.8 we can show that the Jacquet-Langlands functor preserves central characters for the locally analytic vectors of admissible Banach representations.
Corollary 1.3 (Corollary 5.3.7).
Let be an admissible Banach representation of over a finite extension of and suppose that has central character . Then, for all , the locally analytic -representation has central character under the natural identification .
Outline of the paper
Section 2 is a preliminary section where we introduce the main objects and tools used in the paper. In Section 2.1 we recall the definition of period sheaves and the construction of the different incarnations of families of Fargues-Fontaine curves following [SW20, §11.2] and [FS24, §II.1]. In 2.2 we briefly recall the construction of the categories of solid almost quasi-coherent sheaves on diamonds of [Man22b], and its relation with smooth representation theory of profinite groups. In 2.3 we recall the construction of the décalage operator of [BMS18] which will be relevant to perform a technical dévisage in the proof of 1.3. Then, in Section 2.4 we briefly recall the basics of the theory of solid locally analytic representations of [RJRC22, RJRC23], in particular we state the locally analytic criterion of Lemma 2.4.1 which is key in the proof of 1.3. Finally, in Section 2.5 we briefly summarize the relationship between representations of reductive groups and equivariant sheaves over flag varieties, making special emphasis in the Lie algebroids appearing in the localization theory of Beilinson-Bernstein [BB81].
We continue with Section 3 which concerns the definition of the local Shimura varieties and some basic Hodge theoretic features of them, we follow [SW20, Lecture XXIII] and [FS24, §III.4 and 5]. In Section 3.1 we discuss some facts about torsors on families of Fargues-Fontaine curves. In Section 3.2 we recall the definition of the moduli space of shtukas of one leg as well as the construction of the Grothendieck-Messing and Hodge-Tate period maps. Then, in Section 3.3 we specialize the previous construction to the situation of local Shimura varieties where we deduce from the general theory of [SW20, Lecture XXIII] a -adic Riemann-Hilbert correspondence for automorphic local systems in Proposition 3.3.4; this formulation of the theory of Scholze-Weinstein will be useful in the computation of the geometric Sen operator of the next section.
Next, in Section 4 we compute the geometric and arithmetic Sen operators for local Shimura varieties. In Section 4.1 we explain the purely representation theoretic construction of the Kodaira-Spencer isomorphism for Shimura varieties which is essentially a reinterpretation of the anchor map of the reductive group acting on the flag variety. This point of view of the Kodaira-Spencer map will allow us to compute the pullback of equivariant sheaves of flag varieties via the Hodge-Tate period maps in terms of automorphic vector bundles and the Faltings extension in Section 4.2, see Theorem 4.2.1. Finally, we use this description of the pullbacks of automorphic vector bundles to compute the geometric and arithmetic Sen operators of Theorems 1.4 and 1.5. The analogue of these theorems for global Shimura varieties were achieved in [RC23, RC24b], and the proofs in the local situation follow exactly the same line of arguments.
We conclude with Section 5 were most of the main theorems stated in the introduction are proven. In Section 5.1 we prove 1.3; the strategy of the proof is to use the locally analytic criterion of Lemma 2.4.1. For this one has to implement a long dévisage up to the point where one is reduced to showing that the proétale (eq. -) cohomology of on a qcqs smooth rigid space is small after applying a décalage operator for some , see 4. As an immediate consequence we obtain 1.1. We conclude this section with the application of 1.3 to local Shimura varieties; we first obtain the independence of locally analytic vectors at infinite level for basic of 1.2, then, with a more careful study of the horizontal actions arising from the two towers, we prove 1.6. In Section 5.2 we compare the de Rham cohomology of the two towers proving 1.7; here the strategy is to relate the de Rham complexes of each tower with a suitable de Rham complex of the sheaf arising from the derivations of both groups and . Finally, in Section 5.3 we prove the compatibility of Scholze’s Jacquet-Langlands functor with the passage to locally analytic vectors for admissible Banach representations proving 1.8; here the key strategy is to rewrite the proétale cohomology of the sheaf in terms of period sheaves and then to exploit the independence of locally analytic vectors at infinite level of 1.2 in order to jump between towers. Finally, using the proof of 1.8 and the compatibility of the horizontal characters for the sheaf of 1.6, we obtain the compatibility of central characters of the Jacquet-Langlands functor of 1.3.
Conventions
In this paper we use the -site of perfectoid spaces as introduced in [Sch22]. We use the theory of solid almost quasi-coherent sheaves of [Man22b], [AM24] and [AMLB]; the use of these cohomology theories is important in order to properly keep track to the condensed or topological structure of cohomology complexes. In particular, this work heavily depends on the theory of condensed mathematics of Clausen and Scholze [CS19, CS20], and in higher category theory for which we refer to [Lur09, Lur17]. A different reason to use condensed mathematics is to have access to the theory of solid locally analytic representations of [RJRC22, RJRC23]. This is important since, even though most of the main theorems involve classical topological representations, the proofs will make appear very general solid representations which are not classical.
Acknowledgements
We thank Johannes Anschütz, Guido Bosco, Arthur-César le Bras, Pierre Colmez, Wiesława Nizioł, Lue Pan and Peter Scholze for enlightening conversations in different stages of this work. We also thank Johannes Anschütz, Guido Bosco and Arthur-César le Bras for corrections and comments in a first draft of the paper. Part of this project was done during the trimester program in Bonn: “The Arithmetic of The Langlands Program” during the summer of 2023, we heartily thank the organizers and the Hausdorff Research Institute for Mathematics for the excellent environment for mathematical discussions and exchanges. The second author wants to thank Columbia University and the Simons Society of Fellows for the wonderful working conditions and support as a postdoc and Junior Fellow.
2. Preliminaries
In this section we introduce the main objects and techniques used in the paper. In Section 2.1 we recall the definition of families of Fargues-Fontaine curves following [SW20, §11.2] and [FS24, §II.1]. Some period sheaves associated to affinoid charts of the curves will be explicitly introduced for reference in later sections. Then in Section 2.2, we recall the definition of the derived categories of solid almost quasi-coherent sheaves of [Man22b]; we shall not need all the power of the six functor formalism, only the existence of these categories and their relation with smooth representations after [Man22b, §3.4]. We continue in Section 2.3 with some basic properties of the décalage operator of [BMS18, §6]; their importance for us will be to kill some small enough torsion in order to apply a locally analytic criterion discussed in the next section. In Section 2.4 we briefly introduce the theory of solid locally analytic representations of [RJRC22, RJRC23], in particular we recall the criterion of [RJRC23, Proposition 3.3.3] for a solid representation of a -adic Lie group to be locally analytic. Finally, in Section 2.5 we state the classical dictionary between representation theory and equivariant quasi-coherent sheaves on flag varieties; in particular we make emphasis in the Lie algebroids over the flag variety appearing in the localization theory of [BB81].
Apart (but not disjoint!) from condensed mathematics, we also use different aspects of -adic Hodge theory. The main objects we study are period sheaves on diamonds [RC23] and the computation of the geometric Sen operators of Shimura varieties [RC24b]. Finally, in order to realize our cohomology groups as honest solid abelian groups we use the categories of solid quasi-coherent sheaves of diamonds of Mann [Man22b] though the full six functor formalism will not be necessary.
2.1. The Fargues-Fontaine curve and sheaves of periods
Let be the category of perfectoid spaces over and let be the full subcategory of perfectoid spaces over . Following [Sch22], we consider the -site of perfectoid spaces. Let be the perfectoid field parametrizing pseudo-uniformizers in and let be the slice category , equivalently, is the category of perfectoid spaces in characteristic with fixed pseudo-uniformizer , and with maps preserving the pseudo-uniformizer. We let and be the -sheaves on mapping an affinoid perfectoid to and respectively. Similarly, we let and be the -sheaves mapping to and respectively. Given we let be the period ring of Fontaine, and denote by the Teichmüller lift.
For consider the sous-perfectoid analytic adic space [SW20, Proposition 11.2.1]
consisting on the locus where is a pseudo-uniformizer, we call this adic space the -curve over .
The space has pseudo-uniformizer . Furthermore, the following properties hold (see [SW20, §11] and [FS24, §II.1])
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•
We have a natural equivalence of diamonds
where is the diamond parametrizing untilts of perfectoid spaces. In particular the formation of is independent of the pseudo-uniformizer of . Moreover, has a natural Frobenius automorphism lifting the Frobenius of .
-
•
Let be the underlying topological space of the adic space. There is a (unique) continuous radius map
sending a rank point to
The radius map and the Frobenius endomorphism are related by the formula
-
•
For a compact interval with rational ends one defines affinoid subspaces
One has but the inclusion is strict.
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•
For an open interval we let be the inverse image of by . This space can be also described as
where runs over all the compact subintervals of with rational ends.
-
•
The relative Fargues-Fontaine curve over is the sous-perfectoid space
We shall call this space the -curve over .
Convention 2.1.1.
From now on all closed rational intervals will be assumed to have rational ends.
Lemma 2.1.2.
Let be affinoid perfectoids of characteristic with fixed pseudo-uniformizer , let be a map in and let be the corresponding map of -curves.
-
(1)
We have equivalences of sites and .
-
(2)
is an open immersion if and only if is so. If is a rational localization then so is .
-
(3)
For a closed or open interval, the map induces a cartesian square
Proof.
Part (1) is a particular case of [Sch22, Lemma 15.6]. The first assertion of (2) follows from (1) and the fact that open immersions of analytic adic spaces are the same as étale maps such that the diagonal is an equivalence. The second assertion of (2) follows from the fact that if then
For part (3) it suffices to deal with the case where is closed, then it follows from the definition of as it is a rational localization involving only and . ∎
Some of the main players in this paper are the sheaves of periods defined by the affinoid subspaces for closed.
Definition 2.1.3.
Let be a compact interval. We define the -sheaves and on to be the -sheafification of the presheaves mapping an affinoid perfectoid to the rings
We also define the -sheaf as the sheaf mapping to .
In the following lemma we consider almost mathematics with respect to the -completion of the -ideal generated by .
Lemma 2.1.4.
Let be affinoid perfectoid.
-
(1)
We have an almost equivalence of derived -adically complete complexes
-
(2)
Let , then we have an isomorphism of -sheaves
where the RHS term is a polynomial algebra with the residue class of .
-
(3)
Suppose that , we have a natural almost equivalence of derived -adically complete complexes
-
(4)
For a compact interval we have a natural equivalence
Proof.
By [Sch22, Proposition 8.8] we have a natural almost equivalence and so an almost equivalence modulo any pseudo-uniformizer. Since as almost -sheaves, by derived Nakayama’s lemma we have an almost equivalence of derived -complexes
proving (1).
Suppose that , we have a short exact sequence of -adically complete -sheaves
(2.1) |
where is the -adic completion of the polynomial algebra over . Indeed, this follows from the fact that one has the presentation for the ring for any affinoid perfectoid :
(2.2) |
endowed with the -adic topology, see [SW20, proof of Proposition 11.2.1]. The equation (2.2) shows that is a regular element of , and taking quotients in (2.1) by yields an isomorphism of sheaves
proving (2).
Then, part (2), the almost acyclicity of and derived Nakayama’s lemma imply that
proving (3).
Finally, part (4) for follows from (3) by inverting pseudo-uniformizers. Moreover, as is the -adic completion of , part (3) also implies that
and . Let us now consider with . By [KHH+19, Lemma 1.8.2], for all affinoid perfectoid we have a short exact sequence
This gives rise to a short exact sequence of -sheaves
(2.3) |
Part (4) follows from part (3) after taking -cohomology of (2.3). ∎
Lemma 2.1.5.
Let be a locally spatial diamond over an affinoid perfectoid space in characteristic . Let be a compact interval and a fixed pseudo-uniformizer of . Then arises from an étale sheaf of via the fully faithful embedding of [Sch22, Proposition 14.10] with .
Proof.
This follows from [Sch22, Theorem 14.12] since is clearly an étale sheaf on perfectoid spaces. Indeed, it suffices to show that is an étale sheaf for a suitable . If this follows from Lemma 2.1.4 (2). For with consider the short exact sequence of -sheaves
Then, is a subquotient of which is étale by the previous case, proving that is étale itself. ∎
2.2. Solid almost quasi-coherent sheaves
In this paper we shall work with cohomologies of Banach sheaves on locally spatial diamonds such as . However, the sheaves we shall consider are not arbitrary; they are actually solid quasi-coherent sheaves over the -curve in the sense of [AMLB]. This promotion to solid sheaves helps to naturally endow their -cohomologies with the structure of solid abelian groups as in [AM24, §4]. Since the sheaves we shall consider will be generic fibers of completed sheaves, it will be enough to use the formalism of solid almost quasi-coherent sheaves with torsion coefficients of [Man22b, §3] that we briefly recall in this section.
Let be the category of perfectoids in characteristic with fixed pseudo-uniformizer . Let be a compact interval and a positive rational number. Consider the sheaf of coefficients on with almost structure generated by .
Definition 2.2.1.
Let be a small -stack with fixed pseudo-uniformizer . The -category of solid almost quasi-coherent -modules is the hypercompletion of the functor mapping an affinoid perfectoid to the almost category of solid -modules .
The category of almost solid modules satisfies strong descent properties:
Proposition 2.2.2.
Let be a totally disconnected perfectoid space. Then the natural map
is an equivalence of -categories.
Proof.
This follows essentially from [Man22b, Theorem 3.1.27]. Indeed, let be an hypercover of by totally disconnected perfectoid spaces, we want to show that the natural map
is an equivalence. Concretely, this amounts to show the following:
-
i.
For the natural map
is an equivalence.
-
ii.
For a cocartesian section of with totalization the natural map
is an equivalence for all .
Suppose first that , then by Lemma 2.1.4 (3) we have that is a polynomial algebra over where is the class of . By [Man22b, Theorem 3.1.27] we have an equivalence of categories
(2.4) |
Consider the maps of augmented cosimplicial diagrams of analytic rings with . For any map consider the commutative square provide by base change
Let be the right adjoint of given by the forgetful functor. Since any map of discrete Huber pairs is steady [Man22b, Proposition 2.9.7 (ii)], the natural transformations of functors is an equivalence. Therefore, the forgetful functors preserve cocartesian sections and induce a functor
which is the right adjoint of the natural base change along , and that fits in a commutative square
Therefore, since the functors are conservative, in order to show (i) or (ii) we can apply where the claim follows from (2.4).
The case of general follows from derived Nakayama’s lemma: for either (i) or (ii) above we have to show that a map of solid -modules is an equivalence. For this, it suffices to check that it is an equivalence after taking derived quotients by where it was already proven. ∎
Finally, we recall how smooth representation theory appears in terms of solid almost quasi-coherent sheaves.
Proposition 2.2.3.
Let be a totally disconnected perfectoid space with pseudo-uniformizer . Let be a locally profinite group acting on and consider the -stack . Then the pullback along the map realizes as the derived -category of semilinear smooth almost representations of (denoted as in [Man22b, Definition 3.4.11]).
Proof.
This follows from the same argument of [Man22b, Lemma 3.4.26]. ∎
Remark 2.2.4.
By construction the -category is the derived category of its heart
. There is an obvious forgetful functor
to the category of almost solid modules over the semilinear solid group algebra . This gives rise a map of derived -categories
This map is not in general fully faithful, see Remark [Man22b, 3.4.18] for a counter example when . However, the fully faithfulness is expected when has a basis of compact open subgroups with uniformly bounded finite -cohomological dimension, eg. when is a -adic Lie group.
2.3. The décalage functor
In the next section we recall some facts about the décalage functor of [BMS18]. For us it will suffice to consider this functor at the level of the homotopy category of the -derived category of modules of an algebra in a topos as in loc. cit.
Let be a ringed topos. Let be the category of complexes of -modules up to homotopy, and the derived category of -modules obtained by inverting quasi-isomorphisms in .
Let be an invertible ideal, and let denote the full subcategory of whose objects are -torsion free complexes. By [BMS18, Lemma 6.1] the (non !) derived category is the localization of along quasi-isomorphisms.
Definition 2.3.1 ([BMS18, Definition 6.2]).
Let . Define a new object with terms
and differentials
making the following diagram commute
By [BMS18, Corollary 6.5] the operator preserves quasi-isomorphisms and extends to a filtered colimit preserving functor
Moreover, the following properties hold:
-
•
For there are natural isomorphisms [BMS18, Lemma 6.4]
-
•
is lax symmetric monoidal, i.e. for there is a natural map
functorial in and , and symmetric in and [BMS18, Lemma 6.7].
-
•
Suppose that the topos is replete. Let , then the natural maps
are equivalences [BMS18, Lemma 6.20]. Here for an object we let be the derived -adic completion.
Remark 2.3.2.
The functor preserves filtered colimits but is not exact, i.e. it does not preserves cones. For example, we have the short exact sequence
but we also have that
and
We shall need the following behavior of the décalage operator with respect to the passage to the special fiber.
Lemma 2.3.3.
Let and , then the natural map
(2.5) |
is an equivalence.
Proof.
Let be an -torsion free complex representing . Then, is represented by the complex with terms
and differentials
where . Therefore, is represented by the complex with
More explicitly, we have
Since , one deduces that
It is straightforward to check that the differentials of are those arising from the cone of , and that the resulting quasi-isomorphism
is the one induced by the map (2.5). ∎
2.4. Solid locally analytic representations
Throughout this paper we will use the theory of solid locally analytic representations of [RJRC22, RJRC23]. In this section we briefly recall some of the main definitions and properties that will be needed later.
Let be the abelian category of solid abelian groups and let be its solid tensor product. for a ring we let be the abelian category of solid -modules. We write for the derived -category of . Let be a compact -adic Lie group and let be the free solid -algebra generated by ; it coincides with the Iwasawa algebra of with coefficients in . We set . The group has a space of locally analytic functions, it can be written as the filtered colimit
where is the affinoid algebra of a decreasing sequence of affinoid groups over
with .
Given a derived solid -representation, its (derived) locally analytic vectors [RJRC23, Definition 3.1.4] is the solid -representation
where
-
•
is endowed with the left regular -action.
-
•
The tensor is endowed with the diagonal -action.
-
•
The -action on arises from the right regular action on .
We say that is (derived) locally analytic if the natural map
is an equivalence. We let be the full subcategory of locally analytic representations. This category satisfies the following properties:
The key lemma that we will use in this paper is the following criterion of locally analyticity:
Lemma 2.4.1.
Let be a connective derived -adically complete solid representation of . Suppose that there is an open compact subgroup , and a finite extension with pseudo-uniformizer , such that for all the map
is homotopic to zero as -module. Then is a locally analytic representation of .
Proof.
We can assume without loss of generality that is an uniform pro--group. By [RJRC23, Proposition 3.3.2] to show that is -locally analytic, it suffices to show that for all it is -locally analytic. Then, we can assume that . The lemma follows from the same argument of [RJRC23, Proposition 3.3.3] applied to and instead of and respectively. ∎
With this criteria one can show that actions of -adic Lie groups on rigid spaces are always locally analytic:
Corollary 2.4.2.
Let be a complete non-archimedean field of characteristic zero. Let be a Tate algebra of finite type over and a compact -adic Lie group acting continuously on . Then is a locally analytic representation of .
Proof.
Let be a ring of definition of , we can suppose without loss of generality that is stable under the action of and that is topologically generated over by finitely many variables . Thus, since the action of on is smooth, there is some open subgroup leaving the variables fixed. But then acts trivially on and by Lemma 2.4.1 is a locally analytic representation of . ∎
2.5. Equivariant sheaves over flag varieties
Let be a reductive group over and let be a conjugacy class of cocharacters of with field of definition . We denote by the flag variety over parametrizing decreasing -filtrations on -representations seen as an algebraic variety, we let denote its analytification as an adic space over as in [Hub96]. Note that is also the flag variety parametrizing increasing -filtrations.
Let be a complete algebraically closed non-archimedean field an let us write and for the base change of the flag varieties to . We fix a cocharacter so that where is the parabolic subgroup parametrizing decreasing -filtrations. We let be its unipotent radical and let be the Levi subgroup, i.e. the centralizer of in . We have a semi-direct product decomposition .
Set . We have an isomorphism of Artin stacks
Therefore, pullback along gives rise an equivalence of quasi-coherent sheaves on the stacks. The previous translates in the classical equivalence of representation categories:
(2.6) |
from -equivariant quasi-coherent sheaves on and algebraic -linear representations of . We write for the inverse of (2.6).
Next, we introduce some notation appearing in the localization theory of Beilinson-Bernstein [BB81]. Let be the Lie algebra of over and let be its base change to . Let and be the Lie algebras of , and respectively. We let , and let and be the -equivariant sheaves over corresponding to the adjoint action of via (2.6). Note that we have inclusions of -equivariant sheaves and an isomorphism . The action of on can be differentiated to a -equivariant -linear map
(2.7) |
where is the tangent space of . The map (2.7) induces an isomorphism
(2.8) |
Similarly, let be the natural -torsor over given by . The action of induces a -equivariant -linear map
with the tangent space of . Taking pushforward along and -invariants, we get a -equivariant map
that induces an isomorphism
Remark 2.5.1.
-
(1)
In order to construct the equivalence (2.6) it suffices to consider a base change to such that the conjugacy class admits a representative. Then the groups and are defined over .
-
(2)
The Lie algebroids , , and as well as the anchor map (2.7) admit natural descent to . Indeed, the descent of the Lie algebroid is nothing but . One has a sub Lie algebroid induced by the derived Lie algebra . Since acts on one has an anchor map by taking derivations
with kernels and respectively. One can then define as the unipotent radical of and (the reason to take the derived Lie algebra is that cannot distinguish the Lie algebra of an unipotent group and a torus).
We finish by introducing some notation that will be relevant in Section 5. Given the cocharacter of we also have an opposite parabolic subgroup parametrizing increasing -filtrations. It is equivalently obtained as . Then, we have the following subgroups of : with Levi quotient . Note that as the centralizers of and are the same, if the Levi subgroup is clear from the context we will write instead. We have another flag variety and the inverse of the equivalence (2.6) is written as . To stress the difference between the Lie algebroids we shall write . We also have Lie algebroids over given by and .
3. Local Shimura varieties
In this section we introduce local Shimura varieties following [SW20]. We first recall some facts about torsors on the Fargues-Fontaine curve, cf. [FS24, §III.4 and 5]. Then, we recall the definition of moduli spaces of shtukas of one leg from [SW20, Lecture XXIII] as well as the construction of the Grothendieck-Messing and Hodge-Tate period maps. Finally, we specialize the set up to local Shimura varieties and deduce a -adic Riemann-Hilbert correspondence for automorphic proétale local systems. This last result is a direct consequence of the theory developed in [SW20], and we only reformulate it in the version that is more convenient for this paper.
Throughout this section we use the notation of [Sch22]. Let denote the -sheaf parametrizing untilts of objects , we let be the open subspace parametrizing untilts in characteristic zero. Given an analytic adic space over we let denote its diamond over . We let be an algebraic closure of and let be the category of perfectoid spaces over . We let be the completion of the maximal unramified extension of . For a finite extension we write . We let denote the Frobenius automorphism of and .
3.1. -torsors over Fargues-Fontaine curves
In this section we recall some facts about torsors over the Fargues-Fontaine curve that we will need throughout the paper. Let be a reductive group over and let be the Kottwitz set of Frobenius-conjugacy classes of elements in [Kot97]. Given and a perfectoid space we let denote the -torsor on obtained via descent from the trivial torsor with Frobenius (in the definition of torsor we take the Tannakian point of view of [SW20, Appendix to Lecture XIX]). Let be the Harder-Narasimhan filtration of . We take the following definition from [FS24, §5.1].
Definition 3.1.1.
Let . The automorphism group of is the -sheaf on groups
Let be the reductive group over mapping a ring to
By [Kot97, §3.3] is the automorphism group associated to the -isocrystal attached to . We have the following structure theorem for the group .
Proposition 3.1.2 ([FS24, Proposition III.5.1]).
One has
where is the subgroup of unipotent automorphisms with respect to the Harder-Narasimhan filtration of . In particular, if is basic, is the -valued points of a pure inner form of .
In order to construct the period maps we need to introduce the -affine Grassmannian.
Definition 3.1.3 ([SW20, Definition 19.1.1]).
Let be an affinoid perfectoid with untilt over . Given an algebraic variety over we shall write for the -sheafification of the presheaf
Similarly we define to be the -sheafification of
The -affine Grassmannian of is the -sheaf over given by the quotient of groups
We shall write for the base change of from to .
Let be a perfectoid and let be an untilt over . By [FS24, Proposition II.1.18] the map
is an effective Cartier divisor. The pullback of to the completion of at is a trivial -torsor. The automorphism group of the trivial -torsor over is then equal to . Thus, pullback along the formal completion gives rise to a group homomorphism of -sheaves
(3.1) |
3.2. Moduli space of shtukas of one leg
In the following section we recall the definition of moduli space of shtukas of one leg and the construction of the Grothendieck-Messing and Hodge-Tate period maps. We shall follow [SW20, §23.3].
Let be a local shtuka datum of one leg, namely, a triple consisting on a reductive group over , an element , and a conjugacy class of cocharacters . Let be the field of definition of . Recall the equivalent definition of the moduli space of shtukas of one leg from [SW20, Proposition 23.3.1].
Definition 3.2.1.
Let be a compact open subgroup. The moduli space of stukas associated to at level is the presheaf on mapping to the isomorphism classes of quadruples where
-
•
is an until of over ,
-
•
is a -torsor on , which is trivial at every geometric point of ,
-
•
is an isomorphism of -torsors
which is meromorphic at and bounded by , and finally
-
•
is a -lattice in the proétale -torsor corresponding to via [SW20, Theorem 22.5.2].
By [SW20, Theorem 23.1.4] the spaces are diamonds living over . We also define the moduli space of shtukas at infinite level.
Definition 3.2.2.
Let be the infinite level moduli space of shtukas. By construction, is the presheaf on parametrizing tuples where
-
•
is an untilt of over .
-
•
is an isomorphism of -torsors
which is meromorphic at and bounded by .
Let be a perfectoid space and let be an -point of . Let be the closed Cartier divisor defined by the untilt. The pullbacks of and to the formal completion at are trivial -torsors. Therefore, the modification is defined by an element . The automorphisms of act on by right multiplication while the automorphisms of act by left multiplication. Therefore, we have two maps to the affine -grassmannian
(3.2) |
by taking a left or right coset respectively. In particular, since is bounded by by hypothesis, the diagram (3.2) actually restricts to
(3.3) |
Proposition 3.2.3.
Let be a local shtuka datum with basic. Define a shtuka datum via , and under the identification . Then there is a natural -equivariant isomorphism
(3.4) |
interchanging the maps and of (3.3).
Proof.
Let and an -point of . The equivariant isomorphism is [SW20, Corollary 23.3.2]. It is given by mapping a modification
to the modification of -torsors
obtained by mapping a -torsor to the -torsor . Then, since the pullback of the torsors and to are trivial, the map seen as an object in is just the inverse of the map , proving that the period morphisms and are exchanged. ∎
3.3. Local Shimura varieties
Recall the definition of a local Shimura datum [SW20, Definition 24.1.1]
Definition 3.3.1.
A local Shimura datum is a triple consisting of a reductive group over , a conjugacy class of minuscule cocharacters , and an element .
Let be a local Shimura datum and let be the field of definition of . We keep the representation theory notation of Section 2.5. Let be an open compact subgroup and consider the moduli space of shtukas associated to at level . By [SW20, Proposition 23.3.3] the period map
is étale. On the other hand, since is minuscule, the Bialynicki-Birula map
is an isomorphism [SW20, Proposition 19.4.2]. This produces an étale map
(3.5) |
Definition 3.3.2.
For let be the unique smooth rigid space over endowed with an étale map such that
as diamonds over . We shall write for the infinite level Shimura variety.
By (3.2) we get a -equivariant diagram of period maps
(3.6) |
In the rest of the section we will translate the diagram (3.6) in terms of -adic Hodge theory of Shimura varieties. More precisely, we shall deduce a Riemann-Hilbert correspondence for proétale local systems arising from algebraic -representations.
Let be the admissible locus of the flag variety. By [SW20, Corollary 23.5.3] the map factors through and the map
is a proétale -torsor.
Definition 3.3.3.
For a closed subgroup we denote
Let be a -adically complete or -Banach continuous representation of . We let be the -sheaf on obtained via descent from the constant -equivariant sheaf on with
for affinoid perfectoid. For an ind-system of -adically complete or Banach representations we define .
We let be a finite extension over over which is split and consider the pullback of the local Shimura varieties and flag varieties to . Furthermore, we fix a Hodge cocharacter which determines parabolic subgroups and of , as well as their unipotent radicals and , and the Levi subgroup 111Taking this finite extension is unnecessary for the forthcoming discussion but it allows us to use the dictionary between representations of the chosen parabolic and -equivariant quasi-coherent sheaves on the flag variety of Section 2.5. We left to the reader the cocharacter-free formulation of the statements in terms of filtered -representations..
Let be a -linear algebraic representation of . Let be the -equivariant flat connection over given by
with Hodge filtration induced by the -filtration of via the functor of (2.6), see Remark 2.5.1 (1). By an abuse of notation we will also write for the restriction to the admissible locus.
Let be the -sheaf over associated to the -representation via Definition 3.3.3. Let be the restriction of to a sheaf on the proétale site of [Sch13]. We have the following Riemann-Hilbert correspondence for local Shimura varieties.
Proposition 3.3.4.
The proétale local system is de Rham in the sense of [Sch13, Definition 8.3] with associated filtered flat connection 222Strictly speaking this notion is only defined for lisse -local systems and over is not of this form. However, it becomes lisse after pulling back to any finite level local Shimura variety.. More precisely, we have a -equivariant map of filtered -sheaves on
(3.7) |
where the -filtration in the left hand side is the trivial one, and the filtration in the right hand side is given by
The action of is trivial on in the left hand side and it factors through and the natural action on in the right hand side.
Remark 3.3.5.
Proof of Proposition 3.3.4.
Let us denote . Since has horizontal sections , we have an isomorphism
in . By [Sch13, Theorem 7.6] is a -lattice of in the proétale site of . By [SW20, Corollary 17.1.9] we can view as a -lattice in the -site of . Thus, we will view as a filtered -module in the -site with for a local generator of the kernel of .
Now let and take an -point of . Given an algebraic representation, let and be the -equivariant vector bundles over defined by the torsors and respectively. By definition of the modification we have a -equivariant isomorphism
where acts trivially on and via the projection on , and acts trivially on and via the projection on . This produces the desired equivariant isomorphism (3.7). The fact that the isomorphism (3.7) is compatible with the filtration follows from the definition of the Bialynicki-Birula map and [SW20, Proposition 19.4.2]. ∎
Given let and let . The Hodge-Tate filtration of is given by
Let be the inverse of the functor (2.6) for the cocharacter . As corollary we deduce that the Hodge-Tate period map encodes the Hodge-Tate filtration.
Corollary 3.3.6.
There is a -equivariant isomorphism of -modules over
where is the (increasing) -filtration of .
Proof.
This is a consequence of Proposition 3.3.4, the definition of the Bialynicki-Birula map and [SW20, Proposition 19.4.2] ∎
Moreover, taking graded pieces in Corollary 3.3.6 one deduces the isomorphism of -torsors on the infinite level Shimura variety, cf. [CS17, Theorem 2.1.3].
Corollary 3.3.7.
Let be an irreducible algebraic representation of the Levi subgroup. There is a natural -equivariant -isomorphism of -modules over
where is the weight of with respect to . In particular, if and denote the natural -torsors living over and respectively (see Section 2.5), we have a -equivariant isomorphism of -torsors over the ringed site
where injects into the center of via , and is the -torsor of trivializations of the Tate twist .
Proof.
This follows after taking graded pieces of the isomorphisms in Corollary 3.3.6 and [Sch13, Proposition 7.9], see also [RC24b, Theorem 4.2.1]. ∎
4. Geometric Sen operators of local Shimura varieties
In this section we compute the geometric Sen operator of local Shimura varieties, proving the local analogue of [RC24b, Theorem 5.2.5]. We keep the notation of Section 3.3, namely we let be a local Shimura datum with reflex field . We let be a finite extension of over which is split and fix a representative of the Hodge-cocharacter . For compact open subgroup we let be the local Shimura variety over at level , we denote by its structural sheaf as a rigid space, and let be its cotangent bundle.
4.1. The Kodaira-Spencer map
In the next paragraph we make explicit the Kodaira-Spencer isomorphism for local Shimura varieties in terms of representation theory over the flag variety. We follow [RC24b, Proposition 5.1.3].
Let be the adjoint representation of over , and let be its associated -equivariant vector bundle with flat connection over . Since is minuscule, has Hodge filtration concentrated in degrees given by
such that
Then, the flat connection induces a map in -pieces
Taking adjoints we get a -equivariant map
(4.1) |
Looking at the fiber at the map (4.1) is nothing but the natural adjoint action of on with :
Therefore, the map induces the -equivariant Kodaira-Spencer isomorphism over the flag variety
(4.2) |
which is the inverse of the dual of the anchor map of (2.8). Note that in particular is already defined over as the anchor map is so, see Remark 2.5.1 (2).
We deduce the following proposition.
Proposition 4.1.1.
Proof.
This follows from the Kodaira-Spencer isomorphism (4.2) and the fact that the map is étale, namely, the filtered vector bundle with flat connection over is the pullback of the analogue filtered vector bundle with flat connection over the flag variety. ∎
We finish this section by rewriting the Kodaira-Spencer map in the form that will be used in the paper. Let be a compact open subgroup. By Proposition 3.3.4 the local system on the admissible locus (see Definition 3.3.3) is de Rham with associated filtered flat connection . Then, Corollaries 3.3.6 and 3.3.7 give rise -equivariant -sheaves on
(4.3) |
Composing (4.2) and (4.3) we get the following incarnation of the Kodaira-Spencer map
(4.4) |
as -equivariant -sheaves on .
4.2. Pullbacks of equivariant vector bundles along
In this section we compute the Faltings extension of the local Shimura varieties in terms of the representation theory of the Hodge-Tate flag variety. For this computation we need to introduce some sheaves. We keep the representation theory notation of Section 2.5.
Let and be the big proétale de Rham sheaves of as in [Sch13]. Let be the Faltings extension, it is an -vector bundle in the proétale site and so it defines naturally a -vector bundle that we denote in the same way. We can write
where is the unit in the symmetric algebra, and where is the natural map. Therefore, we can see as a -sheaf which is a filtered colimit of -vector bundles. See also [RJRC22, Remark 2.1.2].
Let be the unipotent radical of the opposite to the standard parabolic and let be its space of algebraic functions. We endow with the unique action of such that
-
•
The restriction to is the left regular action, i.e
for and .
-
•
The restriction to is the adjoint action, i.e.
for , and .
By [RC24b, Proposition 3.3.1] the algebra has an increasing -filtration with graded pieces .
Recall that for an algebraic -representation we let denote the -equivariant quasi-coherent sheaf over associated to via (2.6). We have the following theorem.
Theorem 4.2.1.
There is a natural -equivariant isomorphism of -algebras over
More precisely, we have a -equivariant isomorphism of extensions
where is the Kodaira-Spencer isomorphism of (4.4).
Proof.
The proof follows exactly the same lines of the proof of [RC24b, Theorem 5.1.4] where the key inputs are the Riemann-Hilbert correspondence of Proposition 3.3.4 and the Kodaira-Spencer isomorphism (4.4). Note that in loc. cit. we denoted , and we have identified , and via the Killing form of the derived Lie algebra of 333Strictly speaking one has to use the Killing form of the derived group to obtain the self duality.. ∎
4.3. Computation of the geometric Sen operators
We finish this section with the computation of the geometric Sen operators. By [RC23, Theorem 3.3.4], for any compact open subgroup , there is a natural geometric Sen operator
(4.5) |
seen as a morphism of -vector bundles over . We have the following theorem.
Theorem 4.3.1.
Proof.
The proof is the same as the one of [RC24b, Theorem 5.2.5] where Theorem 4.2.1 replaces [RC24b, Theorem 5.1.4]. ∎
Corollary 4.3.2.
The geometric Sen operator (4.5) is a -equivariant map of -sheaves over .
Proof.
This follows from the fact that the pullback along of the map is -equivariant. ∎
We finish this section with the vanishing of higher locally analytic vectors for the sheaf and the computation of its arithmetic Sen operator. Let be the -adic completion of an algebraic closure. Let be a compact open subgroup, and let be the left regular locally analytic representation of . Consider the -sheaf over of Definition 3.3.3 which is a filtered colimit of Banach -linear -sheaves.
Theorem 4.3.3.
Let be an open affinoid subspace admitting an étale map to a product of tori that factors as a finite composition of rational localizations and finite étale maps. Let be the pullback of , then
(4.6) |
sits in degree and is equal to the locally analytic vectors of . Here the completed tensor product is a filtered colimit of -completed tensor products obtained by writing as a colimit of Banach sheaves, it coincides with the solid tensor product of [AM24, Section 4.1].
Furthermore, the action of on by derivations kills . In particular we have an horizontal action of on . Moreover, the space has an arithmetic Sen operator as in [RC24b, Theorem 6.3.5] given by the opposite of the derivative of the Hodge cocharacter .
Proof.
The equivalence of (4.6) follows from the same proof of Proposition 6.2.8 (1) in [RC24b]. The vanishing of the action of on is Corollary 6.2.12 of loc. cit.. Finally, the existence and computation of the arithmetic Sen operator is Theorem 6.3.5 of loc. cit.. Note that in [RC24b] the statement of the theorem involves proétale cohomology and not -cohomology, these two are naturally the same thanks to the -decent results of [AM24, Theorem 5.6]. ∎
5. Locally analytic vectors at infinite level
In this last section we show the main results of this paper. First, in Section 5.1 we study the locally analytic vectors of period sheaves at infinite level local Shimura varieties. In particular, we prove that when is basic the locally analytic vectors are independent of the two towers of local Shimura varieties (5.1.9), generalizing a result of Pan for the Lubin-Tate tower [Pan22b, Corollary 5.3.9]. Then, in Section 5.2 we prove that, for basic, the colimit of compactly supported de Rham cohomologies as the level goes to are independent of the two towers (Theorem 5.2.2), this result has also been independently obtained by Guido Bosco, Wiesława Nizioł and the first author. Finally, in Section 5.3 we prove that the -adic Jacquet-Langlands functor of Scholze [Sch18] for the Lubin-Tate tower is compatible with the passage to locally analytic vectors (Theorem 5.3.6).
5.1. Locally analytic vectors of towers of rigid spaces
Let us fix a perfectoid field in characteristic zero with tilt , we let be a pseudo-uniformizer with . Throughout this section we suppose that contains all -th power roots of unit. For all rational we shall take an element with whenever it exists (similarly for ). Let and be two compact -adic Lie groups and a smooth qcqs rigid space over endowed with an action of . Suppose we are given with an -equivariant proétale -torsor seen as a diamond over , so that has a commuting action of .
Let be a compact interval with rational ends and let be the period sheaf on the -site as in Definition 2.1.3. We can write with a -adically complete sheaf. Set . Consider the solid -vector space with solid structure induced from the presentation
where is a discrete -complex, equal to the étale cohomology
by [Sch22, Proposition 14.7]. Equivalently, it is the pushforward along of seen as a solid sheaf as in [AM24, §4].
The action of on gives rise to the structure of an almost smooth representation on by Proposition 2.2.3 which then can be seen as an almost module over via Remark 2.2.4. Then, after taking limits and colimits, the solid -vector space has a natural action of , and so it gives rise an object in the derived category of solid -linear -representations (even an object in the derived -category of semilinear solid representations of over the Huber pair , namely the -category ). We want to prove the following theorem:
Theorem 5.1.1.
The natural map
from -locally analytic vectors to -locally analytic vectors is an equivalence.
Proof.
We can assume without loss of generality that both and are uniform pro--groups. We shall consider almost mathematics with respect to .
The strategy to prove Theorem 5.1.1 is to apply the locally analytic criterion of Lemma 2.4.1 for the group for suitable “lattices” of . We employ this strategy in different steps. We first make some formal reductions.
Lemma 5.1.2.
Suppose that Theorem 5.1.1 holds for smooth affinoid rigid spaces admitting toric coordinates . Then it holds for general qcqs smooth rigid space .
Proof.
We first show that Theorem 5.1.1 holds for a quasi-compact and separated rigid space . Let be an affinoid cover of by subspaces admitting toric charts and let be the poset of finite intersections of the . Any finite intersection is then affinoid and admits a toric chart. For all let us write . Thus, we have that
The claim follows since the functor of locally analytic vectors commutes with finite limits (being an exact functor of stable -categories). Now, for general qcqs, we argue as before by taking a finite affinoid cover , and noticing that any finite intersection is a quasi-compact separated rigid space. ∎
From now on we suppose that has toric coordinates .
5.1.1. Modifying the locally analytic functions
First, we can write the left regular representation as a colimit of analytic Banach representations of with a suitable space of -analytic functions endowed with a left regular action. We can fix compatible -lattices and define the -adically complete -sheaf over obtained by proétale descent along the -torsor , see Definition 3.3.3. We set .
Lemma 5.1.3.
There is a natural -equivariant isomorphism of solid abelian groups
where the completed tensor in the RHS term is a -adically complete tensor product.
Proof.
Recall that both and are pseudo-uniformizers in . Since is qcqs we can write
Thus, since is compact, we get that
where the spaces and have the left regular action of , the first equality is solid group cohomology as in [RJRC22, Definition 5.1 (1)], and in the second equality we use that the trivial representation is a compact -module thanks to the Lazard resolution which exists since is an uniform pro--group.
Now, since both and are almost bounded to the right and derived -complete, we have by [Man22b, Proposition 2.12.10 (i)] that the solid tensor product is derived -complete and almost equal to
(5.1) |
where in the second term we use that is qcqs and that is a discrete -module. We get that
(5.2) | ||||
where in the first equality we use (5.1), the fact group cohomology for commutes with limits, and that is also commutes with colimits since is uniform pro-. The second equality we use Proposition 2.2.3 and [Man22b, Remark 3.4.12] to compare solid and smooth cohomology. In the third equality we also use Proposition 2.2.3 and the fact that -cohomology is the pushforward along the map . In the last equality we use that cohomology commutes with derived limits of sheaves and that is derived -complete. This proves the lemma. ∎
The objects are -adically complete solid -representations over , where the -action arises from the action on and the -action is induced by the right regular action on . To prove Theorem 5.1.1 it suffices to show the following:
Dévisage 1.
The solid -representation
(5.3) |
is locally analytic.
To prove 1, we need to modify a little bit more the lattices .
5.1.2. Modifying the sheaf of periods
Let us write .Consider the -adically complete complex
(5.4) |
and take the lattice of (5.3) given by
(5.5) |
5.1.3. Modifying the level
For an open compact normal subgroup let . Then
is just a finite colimit (given by the invariants of ) of
Since the category of solid locally analytic representations is stable under colimits by [RJRC23, Proposition 3.2.3], to show 1 it suffices to prove the following statement:
Dévisage 2.
There is an open compact subgroup such that
(5.6) |
is a locally analytic representation of .
We shall take such that the -module is isomorphic to the trivial representation for some fixed that we shall choose in Section 5.1.5.
5.1.4. Applying the decalage functor
Finally, it is well known that the proétale cohomology of has some junk torsion (eg. see [BMS18]), this makes difficult to apply the analyticity criterion of Lemma 2.4.1 to the lattice of 2. A way to solve this problem is to modify the lattice a little bit by applying a décalage functor. First, we need to guarantee that the décalage functor preserves the structure of a solid representation, for this it suffices to see that the category of solid representations of a profinite group can be obtained as the derived category of abelian sheaves on a ringed topos. This is a consequence of the next lemma:
Lemma 5.1.4 ([Man22a, Lemma 10.3]).
Let be a profinite group, and a nuclear -algebra. Then there is a natural equivalence of -categories
between solid sheaves on the proétale site of the -stack with -coefficients, and the category of -linear solid representations of .
Proof.
The result in loc. cit. is only stated for , let us see that this is actually not necessary. Indeed, the proétale site of is independent of the prime used in the definition of -stacks where is considered. So we could have taken as an object in -stacks for perfectoid spaces in characteristic and still get the same conclusion. ∎
By taking we can apply the décalage functor for any rational to -linear solid representations of .
For rational, to be determined in Section 5.1.5, we shall consider the following lattice of (5.6)
(5.7) |
In this way, to show 2 it suffices to prove the following:
Dévisage 3.
There exits and such that the -complete lattice
satisfies the hypothesis of Lemma 2.4.1 for the action of .
5.1.5. Reduction to
We finally perform the last dévisage in the proof of Theorem 5.1.1. Let us write so that . Thus, we shall make the following choices:
-
i.
We take such that the action of on is trivial. In particular, as is a torsion free -adically complete -module, the -representation is isomorphic to a direct sum of copies of .
-
ii.
We take .
Step 1. We first have to guarantee that is -adically complete and bounded to the right. The first claim follows from [BMS18, Lemma 6.20] and the fact that is -adically complete. To see that it is bounded to the right, by -adically completeness and since the décalage functor kills -torsion, it suffices to see that
is almost bounded to the right. By (5.4), the complex is constructed with terms given by . Thus, it suffices to show that
is bounded to the right. By the choice of , we know that is isomorphic to a direct sum of copies of which by Lemma 2.1.4 (2) is almost isomorphic to a polynomial algebra
(5.8) |
Hence, we are reduced to see that
is almost bounded to the right, which is clear as is an affinoid smooth rigid space.
Step 2. Since and are both pseudo-uniformizers of , if the hypothesis of Lemma 2.4.1 holds for a power of then, after base change by a sufficiently ramified extension of , the hypothesis will hold for the pseudo-uniformizer of of . Indeed, we just need to pick such that .
Step 3. We will show that there is an open compact subgroup such that for all the map on
(5.9) |
is homotopic to zero as -module.
By Steps 1 and 2 and Lemma 2.4.1 we will obtain that the -representation (5.6) is locally analytic proving Theorem 5.1.1.
By Lemma 2.3.3 the object (5.9) is equivalent to
(5.10) |
By the choice of , the proétale sheaf is isomorphic to a direct sum of copies of . Therefore, since the décalage functor commutes with direct sums [BMS18, Corollary 6.5], it suffices to show that for all the operator is homotopically equivalent to zero when acting on
By the definition of in (5.4), and since and are divisible by in , we have that
Finally, by (5.8) and since preserves shifts and direct sums, we are reduced to show the following dévisage:
Dévisage 4.
There is an open compact subgroup such that for all the operator on
is homotopic to zero as -module.
5.1.6. Final computation
We now prove 4. We can assume without loss of generality that and so . By Lemma 5.1.2 we can also assume that has toric coordinates . Let be the perfectoid torus and let the Galois group of over . For we let and , similarly we let . By [RC23, Proposition 3.2.3] the pair is a strongly decomposable Sen theory in the sense of [RC23, Definition 2.2.6]. In particular, we have Sen traces with kernel . Thus, by letting , there is some such that the cokernel of the map
as well as the group cohomology are killed by . Since we have an almost equivalence
there exists some depending on such that we have an equivalence
(5.11) |
of -complexes. Let us now justify that (5.11) can be promoted to an equivalence of smooth -representations for some small enough. Indeed, by [Sch18, Lemma 2.3] there is an open subgroup such that the action of can be lifted from to an action on . Moreover, since for all the conjugation is another lift of the action of to , by refining and using [Sch18, Lemma 2.3] again we can suppose that both the actions of and on commute. This shows that the map (5.11) can be upgraded to a map of smooth -representations as wanted.
But then, by Corollary 2.4.2, we can shrink so that it acts trivially on . Thus, for the action of on the left hand side of (5.11) is homotopic to zero as -module finishing the proof of Theorem 5.1.1.
∎
Remark 5.1.5.
Theorem 5.1.1 will hold for a much larger class of -sheaves or complexes following essentially the same proof. For example it holds under the following conditions which hold for and -vector bundles:
-
(a)
The complex is of the form with a connective derived -complete sheaf such that arises from the étale site of (in particular is a solid sheaf as in [AM24, §4]).
-
(b)
There is some such that is a retract of a -sheaf of the form with a complex of -modules.
Indeed, one has to prove 3 for the cohomology . But since is qcqs and the décalage operator sends retracts to retracts, the criterion of Lemma 2.4.1 holds for this lattice if it does for
Using the symmetric monoidality of the décalage operator [BMS18, Proposition 6.8] one is reduced to 4.
An immediate corollary of Theorem 5.1.1 is that the cohomology groups of qcqs smooth rigid spaces endowed with an action of a -adic Lie group is locally analytic.
Corollary 5.1.6.
Let be a qcqs smooth rigid space over a perfectoid field admitting all -th power roots of unit. Suppose that is endowed with a continuous action of a -adic Lie group . Then for any compact interval the -cohomology
is a solid locally analytic -representation.
Proof.
This is a particular case of Theorem 5.1.1 where . ∎
5.1.7. Conclusion for local Shimura varieties
In this paragraph we apply Theorem 5.1.1 to local Shimura varieties. Recall that denotes a local Shimura datum, and for a compact open subgroup we have the local Shimura variety of level . We also let be the infinite level local Shimura variety seen as a diamond over . We fix be a complete algebraically closed extension, and consider the base change of local Shimura varieties to .
Definition 5.1.7.
We let be the restriction of the -sheaf to the topological space and let be the subsheaf mapping a qcqs open subspace to the space of -locally analytic vectors
where is the stabilizer of . If is clear from the context we write instead of .
Remark 5.1.8.
The fact that is a sheaf follows from [RC24b, Lemma 6.2.2].
We obtain a generalization of a theorem of Lue Pan for the Lubin-Tate space, see [Pan22b, Corollary 5.3.9].
Corollary 5.1.9.
For any -adic Lie group and any qcqs open subspace the natural map
is an equivalence. In particular, if is basic we have an equality of subsheaves of
More generally, for basic and a compact interval, we have an equivalence of derived solid locally analytic representations of
Proof.
The first claim follows from Theorem 5.1.1 and Remark 5.1.5, and the fact that has no higher locally analytic vectors by Theorem 4.3.3. The claim when is basic follows also from Theorem 5.1.1 and the fact that for a compact open subgroup, the quotient is the diamond attached to a local Shimura variety of level for the dual Shimura datum . ∎
In the following we shall write and for the base change to of the flag varieties and respectively. For basic, we write for , by 5.1.9 there is no ambiguity in the locally analytic vectors for the group or . Let and be the Lie algebroids over the Hodge-Tate and Grothendieck-Messing flag varieties respectively. Let be the natural filtration on with Levi quotient (resp. for over with Levi quotient ). They arise from the -equivariant filtration and Levi quotient (resp. for the -equivariant filtration and Levi quotient ). We identify the pullback of and to via Corollary 3.3.7 (after taking locally analytic vectors) and denote it . The following is the generalization of [Pan22b, Corollary 5.3.13].
Theorem 5.1.10.
The actions of and on vanish. Furthermore, the actions of and on by derivations are identified via the pullback
In particular, the central character of the actions of and on agree under the natural isomorphism of the center of the enveloping algebras .
Proof.
The vanishing for the action of the geometric Sen operators follows from Theorem 4.3.3. We now prove the relation between the horizontal actions. In the following we forget about the action of the Galois group of and fix a trivialization of the Tate twist obtained by fixing a sequence of -th power roots of unit . In the following all completed tensor products are solid.
Let be the ringed space whose underlying topological space is and sheaf of functions given by the algebra . We have locally analytic Hodge-Tate period maps
Let be a representation of the Levi , taking locally analytic vectors in Corollary 3.3.7 we get -equivariant isomorphisms of vector bundles over
(5.12) |
Let and be the natural -torsors, the equation (5.12) gives rise to a natural isomorphism of -torsors over
Thus, if and denote the analytification of the algebraic torsors over the flag varieties, the period maps refined to a mixed period map
Note that the Lie algebra acts on by derivations, and by construction both horizontal actions and are identified after pullback (similarly for the infinitesimal actions of and ). Therefore, in order to show the theorem it suffices to show that the map of rings
is dense in a suitable sense. To make this precise, for any compact open subgroup consider the -equivariant sheaf over given by and consider the colimit
Define
to be the invariant subspace of -horizontal sections for the left regular action. Let be the subalgebra of -smooth sections, equal to the colimit of the structural sheaves of the finite level local Shimura varieties . By the proof of [RC24b, Proposition 6.2.8] (more precisely, Lemma 6.2.9), the pullback to
is a filtered colimit of ON Banach -modules which are relatively locally analytic in the sense of [RC23, Definition 1.0.1] (resp. for the pullback of ). Moreover, the -smooth vectors of (more precisely, of its restriction to a sheaf on the topological space ) are well defined (by writing the module as a colimit of -representations as ), and by construction they consist on the algebra . By [RC23, Theorem 3.3.2 (2)] and the computation of the geometric Sen operators in Theorem 4.3.1, we have that
But now has trivial geometric Sen action, then [RC23, Theorem 3.3.2 (3)] implies that the orbit map (equivariant for the right regular action in the RHS)
extends to a -equivariant and -linear isomorphism
(5.13) |
where the action of on the right hand side term is via the right regular action.
Let us write . Over we also have the Lie algebroid which is nothing but the relative tangent space of over and we have an isomorphism
equivariant for infinitesimal action of for the left and right regular actions, and the action on the coefficients (by writing this sheaf as colimit of Banach sheaves where the actions integrate to compact open subgroups). Thus, we have a commutative diagram
where we the horizontal maps are the orbit maps and the vertical maps are the natural inclusions. This diagram together with (5.13) show that both horizontal Levi actions of and agree on are they do over and they transform in the natural left regular action of
on . This ends the proof of the theorem. ∎
5.2. De Rham cohomology of the two towers
In this section we show that the sheaf of Definition 5.1.7 produces an isomorphism between the de Rham cohomology (with compact supports) of the two towers for a duality of local Shimura varieties. Similar results have been obtained independently by Bosco-Dospinescu-Niziol. In order to state the theorem, wee keep the notation prior Theorem 5.1.10. Let and consider the mixed Lie algebroid over
obtained as the pullback of the tangent space of via the map . By Theorem 5.1.10 this Lie algebroid acts by derivations on , compatible with the derivations on . Indeed, let us write by the base change of from to . Similarly, let be the base change of from to . Theorem 5.1.10 also provides an isomorphism
Then, is the quotient of by the Lie algebroid sitting in the cartesian square
where is the anti-diagonal map. Since acts trivially on , the action by derivations of on descends to .
Remark 5.2.1.
With some additional effort one can prove that is formally smooth over and that its tangent space is given by but we will not need this fact for the applications in this paper.
We have the following theorem
Theorem 5.2.2.
There are natural -equivariant isomorphisms of de Rham complexes over the topological space
(5.14) |
where:
-
(1)
is the de Rham complex of the colimit of structural sheaves of the finite level local Shimura varieties with .
-
(2)
is the de Rham complex of the colimit of structural sheaves of the finite level local dual Shimura varieties with .
-
(3)
is the de Rham cohomology of with respect to the action of the Lie algebroid acting by derivations.
In particular, we have a natural -equivariant isomorphism of de Rham cohomologies with compact supports
Remark 5.2.3.
One can use the theory of the analytic de Rham stack of [RC24a] to prove Theorem 5.2.2. Indeed, as it was explained by Scholze to the second author, the formation of the analytic de Rham stack descends to (a suitable notion of) diamonds and, at least for what cohomology concerns, commutes with cofiltered limits of qcqs maps. Thus, Theorem 5.2.2 should be thought as an evidence to the fact that one has an equivalence of analytic de Rham stacks
After taking quotients by the smooth groups and such an equivalence would also prove that one has an equivalence of analytic stacks
between the analytic de Rham stacks of the quotients of the admissible locus of the flag varieties. This gives rise to a “Jacquet-Langlands equivalence” of equivariant analytic -modules. We shall not prove this fact in this paper, instead we will give a first shadow of this compatibility of analytic de Rham stacks in the locally analytic Jacquet-Langlands functor for the Lubin-Tate tower in Section 5.3.
Proof of Theorem 5.2.2.
Let and be the tangent spaces of and respectively. We have identifications and via the anchor map (2.7). By construction of the Lie algebroid , we have a short exact sequence
The pullback along the inclusion of in the direct sum corresponds to the Lie algebroid (similarly the pullback for the inclusion of is ). Thus, we can write the -de Rham complex as the composite
Therefore, in order to prove the quasi-isomorphisms (5.14) it suffices to show the two following facts:
-
(1)
The natural map is an equivalence.
-
(2)
The natural map is an equivalence.
These claims are symmetric with respect to the period maps, so it suffices to prove the first.
Let us write for the infinite level Shimura variety and for its quotient by an open compact subgroup. Let be the Hodge-Tate proétale sheaf of that appeared in Theorem 4.2.1, let be the unipotent radical and let be the space of algebraic functions of endowed with the natural action of as in Section 4.2. By Theorem 4.2.1 we have that
(5.15) |
Let be the projection of sites, then by [Sch13, Proposition 6.16] one has that
On the other hand, by taking locally analytic vectors for the action of , by the vanishing of higher locally analytic vectors of of Theorem 4.3.3, and the group cohomology comparisons of [RJRC23, Theorem 6.3.4], one deduces that for open affinoid and one has
where the second equality is decent along the -torsor . The third equality is the comparison between solid and locally analytic group cohomology of [RJRC23, Theorem 6.3.4]. The fourth equality follows from the projection formula of locally analytic vectors [RJRC23, Corollary 3.1.15 (3)] and the isomorphism (5.15). The fifth equality follows from the vanishing of higher locally analytic vectors of Theorem 4.3.3. Finally, the sixth equality is the Lie algebra/smooth vs locally analytic cohomology comparison of Theorem [RJRC23, Theorem 6.3.4].
Taking colimits as , we deduce that
(5.16) |
But since is an affine space we know that
taking the associated equivariant vector bundles over the flag variety and taking pullbacks along one deduces that
Combining this with (5.16), and by computing -lie algebra cohomology in two steps, one gets that
proving what we wanted.
The claim about the cohomology comparisons for the de Rham cohomology with compact supports follows for example by using the definition of compactly supported de Rham cohomology arising from the six functor formalism of analytic -modules of [RC24a]. One can also argue by using the adhoc definition of [GK00]. Indeed, the compactly supported cohomology of the de Rham complex of loc. cit. is nothing but the compactly supported cohomology of the de Rham complex seen as a sheaf on the underlying Berkovich space of . To see that this cohomology with compact supports is well defined one can argue as follows: the map gives rise to a -torsor of Berkovich spaces
(5.17) |
The space is a locally finite dimensional Hausdorff space (being the Berkovich space of a rigid space) and [HM24, Theorem 4.8.9 (i)] implies that has a well define functor of cohomology with compact supports for sheaves over (in the language of loc. cit. it is -fine). Since (5.17) is represented in profinite sets, is also a -fine map (this follows from [HM24, Theorem 3.4.11 (ii)] since any maps between profinite sets is -fine by construction, see Section 3.5.16 in loc. cit.), i.e. it has a well defined functor of cohomology with compact supports. ∎
5.3. The Jacquet-Langlands functor for admissible locally analytic representations
In this last section we recall the definition of the Jacquet-Langlands functor of [Sch18] for admissible Banach representations. We then proof that this functor is compatible with the passage to locally analytic vectors.
5.3.1. Scholze’s Jacquet-Langlands functor
Let be an integer and a finite extension with ring of integers and a uniformizer. Let be the residue field of . Consider the group , the cocharacter given by with occurrences of , and corresponds to a formal -module over of dimension and -height . Let be the division algebra over of invariant , we have . Finally, we fix the -completion of an algebraic closure of .
Definition 5.3.1.
We let be the functor on formal schemes over sending to the set of isomorphism classes of pairs , where is a formal -module, and is a quasi-isogeny of formal -modules, where .
By [RZ96] the functor is representable by a formal scheme over , which is formally smooth and locally formally of finite type. We let denote the generic fiber of as a rigid space.
Theorem 5.3.2 ([SW20, Corollary 24.3.5]).
There is a natural equivalence of diamonds with .
Let . In this situation the -equivariant period maps (3.6) restrict to a diagram
where
-
•
is a proétale -torsor and acts on via the natural inclusion of the map .
-
•
is a proétale -torsor and is the -stable open Drinfeld space obtained by removing all -rational hyperplanes.
Thus, we have an equivalence of -stacks
The Jacquet-Langlands functor is defined as follows.
Definition 5.3.3.
Let be a -power torsion admissible representation of over and let be the étale sheaf over obtained by descent along . The Jacquet-Langlands functor is the functor mapping such to the complex of smooth -representations
Theorem 5.3.4 ([Sch18, Theorem 1.1]).
Let be a -power torsion admissible representation of over , then is a complex of admissible representations of . In other words, for all the cohomology
is an admissible representation of .
For convenience we shall consider the -completed analogue of Theorem 5.3.4. Let be a -adically complete admissible representation of over , we shall write by the pro-étale sheaf over given by the limit of étale sheaves . Finally, we denote by the -adically complete -representation
Corollary 5.3.5.
Let be a -adically complete admissible representation of , then is a complex of -adically complete admissible representations of . In other words, the cohomology groups
are -adically complete admissible representations of . Moreover, we have that
Proof.
Let be a compact open subgroup which we assume to be an uniform pro--group. Taking -duals the complex is a -adically complete module over the Iwasawa algebra whose reduction modulo is a perfect -complex by Theorem 5.3.4, this implies that is itself a perfect complex of -modules and so can be represented by a complex of admissible representations of . The rest of the statements are classical and left to the reader, see for example [Eme06, Proposition 1.2.12]. ∎
5.3.2. Locally analytic Jacquet-Langlands functor
Next we show that the Jacquet-Langlands functor of Definition 5.3.3 is compatible with locally analytic vectors. Let be an admissible locally analytic representation of over , we let be the proétale sheaf over whose -points for an affinoid perfectoid are given by
where
-
•
For a perfectoid space the algebra is the space of continuous functions from to .
-
•
The completed tensor product is a tensor product of LB representations (equivalently a solid tensor product).
-
•
The group acts via the diagonal action.
This is the same as the proétale solid sheaf on obtained by descent from the constant sheaf on via [AM24, Corollary 4.5].
Theorem 5.3.6.
Let be a -adically complete admissible representation and its LB subrepresentation of locally analytic vectors. Then there is a natural equivalence
(5.18) |
where the left hand side is the complex of derived -analytic vectors of the solid -representation . Moreover, for all we have an isomorphism of locally analytic admissible -representations
(5.19) |
Proof.
In the following proof we work with the derived -categories of solid sheaves of diamonds as in [AM24, §4].
Step 0. The equivalence in Eq. 5.19 follows from Eq. 5.18. Indeed, the object is a complex with cohomologies given by admissible Banach representations of . By [RJRC22, Proposition 4.48] (see also [RC24b, Proposition 2.3.1]) the higher locally analytic vectors of a Banach admissible representation vanish, then by the spectral sequence of [RC24b, Theorem 1.5] one deduces that
Step 1. We first reinterpret the problem using the period sheaves. By [FS24, Proposition II.2.5] we have a short exact sequence of proétale sheaves
Taking solid (eq. -complete in this case) tensor products with the sheaf we get a short exact sequence
Taking proétale cohomology we get an exact triangle
On the other hand, taking LB-completed tensor products we get a short exact sequence of proétale sheaves
Therefore, to prove the theorem it suffices to show that for all compact interval, we have a natural equivalence of representations of
(5.20) |
Step 2. We now reduce the proof of (5.20) to affinoid subspaces of . Let be the projection of sites and let be a finite rational open cover of . Then, for any proétale sheaf over we have equivalences of complexes
functorial on , where the left hand side is the Čech cohomology given by
with the poset of finite intersections of elements in .
Therefore, in order to show (5.20) it suffices to prove that for a rational open subspace we have a natural equivalence
(5.21) |
Step 3. Finally, we prove (5.21). We can assume without loss of generality that is a rational subspace admitting a section . Let be a compact open subgroup stabilizing and let . Then, we have that
In the first equivalence we use descent along the -torsor and write explicitly the definition of -locally analytic vectors. The second equivalence is clear as is qcqs and is a Banach space, namely this follows from the analogue computations of the equation (5.2) in the proof of Lemma 5.1.3. The third equivalence follows from projection formula of locally analytic vectors [RJRC23, Corollary 3.1.15 (3)] and the fact that is a trivial -representation. The fourth equivalence is 5.1.9. The fifth equivalence follows from the projection formula of locally analytic vectors and the fact that as is an admissible representation. The sixth equivalence is the projection formula again. The last equivalence is descent along the torsor . This finishes the proof of the theorem. ∎
As a corollary we can prove that the Jacquet-Langlands functor for Banach admissible locally analytic representations preserves central characters.
Corollary 5.3.7.
Let be an admissible Banach representation of over and suppose that has central character . Then, for all , the locally analytic -representation has central character under the natural identification .
Proof.
The statement can be proven after base change to . By [Sch18, Theorem 3.2] we have a natural equivalence
Then, by (5.20) we deduce an -equivariant equivalence
thus it suffices to show that the RHS term has central character given by . By picking a suitable affinoid cover of as in Steps 2 and 3 of the proof of Theorem 5.3.6, we are reduced to show that for any small enough open affinoid with stabilizer , the central character of for the action of is . Let be the pullback of to infinite level, by Step 3 of the proof of Theorem 5.3.6 we have that
but by taking small enough, the vanishing of higher locally analytic vectors of Theorem 4.3.3 implies that
The corollary follows from the identification of the central horizontal actions on of Theorem 4.3.3 and the fact that the central actions of factor through the horizontal actions. ∎
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