{ "id": "1610.00284", "version": "v1", "published": "2016-10-02T14:36:08.000Z", "updated": "2016-10-02T14:36:08.000Z", "title": "Whittaker supports for representations of reductive groups", "authors": [ "Raul Gomez", "Dmitry Gourevitch", "Siddhartha Sahi" ], "comment": "23 pages", "categories": [ "math.RT" ], "abstract": "Let $F$ be either $\\mathbb{R}$ or a finite extension of $\\mathbb{Q}_p$, and let $G$ be the group of $F$-points of a reductive group defined over $F$. Also let $\\pi$ be a smooth representation of $G$ (Frechet of moderate growth if $F=\\mathbb{R}$). For each nilpotent orbit $\\mathcal{O}$ we consider a certain Whittaker quotient $\\pi_{\\mathcal{O}}$ of $\\pi$. We define the Whittaker support WS$(\\pi)$ to be the set of maximal $\\mathcal{O}$ among those for which $\\pi_{\\mathcal{O}}\\neq 0$. In this paper we prove that all $\\mathcal{O}\\in\\mathrm{WS}(\\pi)$ are quasi-admissible nilpotent orbits, generalizing some of the results in [Moe96,JLS]. If $F$ is $p$-adic and $\\pi$ is quasi-cuspidal then we show that all $\\mathcal{O}\\in\\mathrm{WS}(\\pi)$ are $F$-distinguished, i.e. do not intersect the Lie algebra of any proper Levi subgroup of $G$ defined over $F$. We also give an adaptation of our argument to automorphic representations, generalizing some results from [GRS03,Shen16,JLS,Cai] and confirming a conjecture from [Ginz06]. Our methods are a synergy of the methods of the above-mentioned papers, and of our preceding paper [GGS].", "revisions": [ { "version": "v1", "updated": "2016-10-02T14:36:08.000Z" } ], "analyses": { "subjects": [ "20G05", "20G20", "20G25", "20G30", "20G35", "22E27", "22E46", "22E50", "22E55", "17B08" ], "keywords": [ "reductive group", "whittaker support ws", "proper levi subgroup", "lie algebra", "moderate growth" ], "note": { "typesetting": "TeX", "pages": 23, "language": "en", "license": "arXiv", "status": "editable" } } }