The increasing subhalo spin with mass is even more pronounced relationship for the Bullock spin parameter shown in [Figure \[piclm2\]]{} because for the Bullock spin the (sub)halo mass has a higher weight (c.f. [Equation \[eqn:peebles\]]{},[Equation \[eqn:bullock\]]{}). This results in a larger discrepancy between [haloes]{} and sub[haloes]{} at the low mass end. In @onions_2013, their samples are from a Milky Way like re-simulation, which contains sub[haloes]{} similar to those found in BoxA. So the subhalo spin distribution in their work is closer to that from BoxA. @onions_2013 suggest that the physical mechanism that drives this difference is mass stripping. Subhalo particles with high angular momentum are stripped preferentially which leads to a decrease in the spin parameter. Sub[haloes]{} with low mass are usually the ones stripped most severely. Our results strongly support the claims @onions_2013 made.

The slightly positive slope of $\lambda_{0,halo}(M_{halo})$ and $\lambda_{0,halo}'(M_{halo})$ is inconsistent with some previous work. They found that $\lambda_{0,halo}$ is constant or has a slightly negative slope ([@bett_2007; @maccio_2007 c.f.]). However we should not forget this trend includes the effect of systematic bias between simulations. Figure 10 in @maccio_2008 shows that $\lambda_{0}'(M_{halo})$ has a slope of 0.005 in a simulation using WMAP1, which is the same 