# A heart for stable equivariant homotopy theory

Let $G$ be a finite group. I wonder whether the following statement is true, known and written down:

There is a t-structure on the stable $G$-equivariant homotopy category such that the associated heart is isomorphic to the category of Mackey functors (on $B_G$).

I feel like someone has told me so, but I can't find a reference. Thanks for your help!

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Could you define "t-structure" and "heart"? –  Dev Sinha Aug 23 '10 at 18:06
@Dev: en.wikipedia.org/wiki/Triangulated_category#t-structures I am pretty sure that the answer to your question is "yes", with truncation functors given by connective covers, but my references aren't handy. –  Tyler Lawson Aug 23 '10 at 19:16
The answer is certainly "yes," but the only proof I know off the top of m head is that you first show that the homotopy category of G-equivariant spectra is equivalent to the homotopy category of "spectral Mackey functors," where the t-structure is easy to write down. (In fact this is an equivalence of infty-categories; I'm still writing up these details.) Presumably there's a more direct proof; I seem to remember some appendix of Gaunce Lewis ... Sorry I can't be of more help! –  Clark Barwick Aug 26 '10 at 16:16

Since G is finite, there is no problem with just repeating the proof in the case $G=e$, using $Z$-graded homotopy group functors on the orbit category. Take $D^{\leq n}$ to be the spectra whose homotopy groups $\pi_q(X^H)$ are zero for $q>n$, and dually for $D^{\geq n}$. The intersection for $n\leq 0$ and $n\geq 0$ consists of the Eilenberg-MacLane $G$-spectra $K(M,0)$ for Mackey functors $M$.