{ "id": "1901.02109", "version": "v1", "published": "2019-01-08T00:11:36.000Z", "updated": "2019-01-08T00:11:36.000Z", "title": "Invertible $K(2)$-Local $E$-Modules in $C_4$-Spectra", "authors": [ "Agnes Beaudry", "Irina Bobkova", "Michael Hill", "Vesna Stojanoska" ], "categories": [ "math.AT" ], "abstract": "We compute the Picard group of the category of $K(2)$-local module spectra over the ring spectrum $E^{hC_4}$, where $E$ is a height 2 Morava $E$-theory and $C_4$ is a subgroup of the associated Morava stabilizer group. This group can be identified with the Picard group of $K(2)$-local $E$-modules in genuine $C_4$-spectra. We show that in addition to a cyclic subgroup of order 32 generated by $ E\\wedge S^1$ the Picard group contains a subgroup of order 2 generated by $E\\wedge S^{7+\\sigma}$, where $\\sigma$ is the sign representation of the group $C_4$. In the process, we completely compute the $RO(C_4)$-graded Mackey functor homotopy fixed point spectral sequence for the $C_4$-spectrum $E$.", "revisions": [ { "version": "v1", "updated": "2019-01-08T00:11:36.000Z" } ], "analyses": { "subjects": [ "55M05", "55P42", "20J06", "55Q91", "55Q51", "55P60" ], "keywords": [ "homotopy fixed point spectral sequence", "functor homotopy fixed point spectral", "mackey functor homotopy fixed point", "picard group contains", "morava stabilizer group" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }