Homogeneous and conformally Ricci flat pure radiation fields

@inproceedings{Wils1989HomogeneousAC,
  title={Homogeneous and conformally Ricci flat pure radiation fields},
  author={Patrick Wils},
  year={1989}
}
Some unsolved problems concerning pure radiation fields in general relativity are studied. The general solutions for homogeneous and for conformally Ricci flat metrics are given. They are all of Petrov type N or O, and contain a hitherto unidentified conformally flat metric. Non-aligned Petrov type III pure radiation metrics are shown not to exist.