Dain’s invariant on non-time symmetric initial data sets
Dain’s invariant on non-time symmetric initial data sets
We extend Dain's construction of a geometric invariant characterising static initial data sets for the vacuum Einstein field equations to situations with a non-vanishing extrinsic curvature. This invariant gives a measure of how much the initial data sets deviates from stationarity. In particular, it vanishes if and only if the …