Peeling properties of lightlike signals in general relativity

The peeling properties of a lightlike signal propagating through a general Bondi--Sachs vacuum spacetime and leaving behind another Bondi--Sachs vacuum spacetime are studied. We demonstrate that, in general, the peeling behavior is the conventional one which is associated with a radiating isolated system and that it becomes unconventional if the asymptotically flat spacetimes on either side of the history of the lightlike signal tend to flatness at future null infinity faster than the general Bondi--Sachs spacetime. This latter situation occurs if, for example, the spacetimes in question are static Bondi--Sachs spacetimes.