Univ. Córdoba, Spain
We find necessary and sufficient conditions ensuring that the vacuum development of an initial data set of the Einstein's field equations admits a conformal Killing vector. We refer to these conditions as conformal Killing initial data (CKID) and they extend the well-known Killing initial data (KID) that have been known for a long time. The procedure used to find the CKID is a classical argument, which is reviewed and presented in a form that may have an independent interest, based on identifying a suitable propagation identity and checking the well-posedness of the corresponding initial value problem. As example applications, we review the derivation of the KID conditions, as well as give a more thorough treatment of the homothetic Killing initial data (HKID) conditions than was previously available in the literature.
Work done in collaboration with Igor Khavkine, (Academy of Sciences of the Czech Republic).