Are wormholes or 'gravastars' mimicking gravitational-wave signals from black holes?

Earlier this year, researchers working on the Advanced Laser Interferometer Gravitational-wave Observatory (aLIGO) made the first ever detection of gravitational waves. The waves are believed to have been created by the merger of two binary black holes, in an event dubbed GW150914. Now, however, new theoretical work done by an international team of researchers suggests that other hypothetical exotic stellar objects – such as wormholes or "gravastars" – could produce a very similar gravitational-wave signal. While it is theoretically possible to differentiate between the different sources, it is impossible to tell whether GW150914 had a more exotic origin than merging black holes because the signal was not strong enough to be resolved.