Chromatic defect, Wood's theorem, and higher real $K$-theories (2402.17519v1)

Abstract: Let $\mathrm{X(n)}$ be Ravenel's Thom spectrum over $\Omega \mathrm{SU}(n)$. We say a spectrum $E$ has chromatic defect $n$ if $n$ is the smallest positive integer such that $E\otimes \mathrm{X(n)}$ is complex orientable. We compute the chromatic defect of various examples of interest: finite spectra, the Real Johnson--Wilson theories $\mathrm{ER(n)}$, the fixed points $\mathrm{EO}_n(G)$ of Morava $E$-theories with respect to a finite subgroup $G$ of the Morava stabilizer group, and the connective image of $J$ spectrum j. Having finite chromatic defect is closely related to the existence of analogues of the classical Wood splitting $\mathrm{ko}\otimes C(\eta)\simeq \mathrm{ku}$. We show that such splittings exist in quite a wide generality for fp spectra $E$. When $E$ participates in such a splitting, $E$ admits a $\mathbb Z$-indexed Adams--Novikov tower, which may be used to deduce differentials in the Adams--Novikov spectral sequence of $E$.