Let (M,g) be some smooth, Riemannian manifold. Let d be the exterior derivative and delta the codifferential on forms. For a smooth vector field X, let LX be the Lie derivative associated to X. We know from Cartan formula that LX=diotaX+iotaXd where iotaX is the interior derivative associated to the vector field X. So it is well-known that LX and d commute: for any arbitrary form omega, we have that LXdomega=dLXomega.
This is, of course, not true for codifferentials. In general [LX,delta]neq0. For certain cases the answer is well known: if X is a Killing vector (LXg=0) then since it leaves the metric structure in variant, it commutes with the Hodge star operator, and so LX commutes with delta. Another useful case is when X is conformally Killing with constant conformal factor (LXg=kg with dk=0). In this case conformality implies that the commutator [LX,∗]=kalpha∗ where alpha is some numerical power depending on the rank of the form it is acting on (I think... correct me if I am wrong), so we have that [LX,delta]proptodelta.
So my question is: "Is there a general nice formula for the commutator [LX,delta]?" If it is written down somewhere, a reference will be helpful. (In the Riemannian case, by working with suitable symmetrisations of metric connection one can get a fairly ugly answer by doing something like deltaomegaproptomathoptrg−1nablaomega and use that the commutators [LX,g−1] and [LX,nabla] are fairly well known [the latter giving a second-order deformation tensor measuring affine-Killingness]. But this formula is the same for the divergence of arbitrary covariant tensors. I am wondering if there is a better formula for forms in particular.)
A simple explanation of why what I am asking is idiotic would also be welcome.
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