R. Beig et No. Murchadha, THE MOMENTUM CONSTRAINTS OF GENERAL-RELATIVITY AND SPATIAL CONFORMAL ISOMETRIES, Communications in Mathematical Physics, 176(3), 1996, pp. 723-738
Transverse-tracefree (TT-) tensors on (R(3),g(ab)), With g(ab) an asym
ptotically flat metric of fast decay at infinity, are studied. When th
e source tensor from which these TT tensors are constructed has fast f
all-off at infinity, TT tensors allow a multipole-type expansion. When
g(ab) has no conformal Killing vectors (CKV's) it is proven that any
finite but otherwise arbitrary set of moments can be realized by a sui
table TT tenser. When CKV's exist there are obstructions-certain (comb
inations of) moments have to vanish-which we study.