On the equivariant $K{U}_G$-local sphere for finite abelian groups

Abstract

We study $K{U}_G$-localization for finite groups. For a finite nilpotent group $G$, we identify the $K{U}_G/p$-local sphere as the fiber of an Adams operation, and reduce the computation of its homotopy Mackey functors to the corresponding computation for the Sylow $p$-subgroup of $G$. At the prime $2$, we compute ${\underline{\pi }}_{\ast }{L}_{K{U}_G/2}{S}_G$ for abelian $2$-groups, resolve the resulting extension problems, and determine the degree-zero Hurewicz image. As a consequence, we completely determine the $\mathbb{Z}$-graded homotopy Mackey functors of $L_{K{U}_G}{S}_G$ for all finite abelian groups. Finally, for an arbitrary finite group $G$, we prove that the $K{U}_G/p$-localization of $G$-spectra splits as a wedge of height-one equivariant Morava $K$-localizations, indexed by conjugacy classes of cyclic subgroups of order prime to $p$.

41 pages. Comments welcome. v2:Revised the extension problems for Mackey functors at the prime 2. v3: Revised section 7 for finite groups