IMPULSIVE LIGHT-LIKE SIGNALS

A general characterisation of an impulsive light–like signal was given1,2. The signal may consist of a shell of null matter and/or an impulsive gravitational wave. Both parts of the signal can be unambiguously identified3,4. The signals can be used to model bursts of gravitational radiation and light– like matter accompanying cataclysmic events such as supernovae and neutron star collisions. Also in high speed collisions of compact objects such as black–holes or neutron stars the gravitational fields of these objects resemble those of impulsive light–like signals when the objects are boosted to the speed of light. Several examples of impulsive light–like signals were presented, in particular those produced by recoil effects5 and by the Aichelburg–Sexl boost of an isolated gravitating multipole source6. The detection of these signals was also discussed7.