Radiative gravitational fields in general relativity

We prove that Penrose's requirements for asymptotic simplicity are formally satisfied by the general metric, (1), which admits both post-Minkowskian and multipolar expansions, (2), which is stationary in the past and asymptotically Minkowskian in the past, (3), which admits harmonic coordinates, and (4), which is a solution of Einstein's vacuum equations outside a spatially bounded region. The proof is based on the setting up, by using the method of a previous work, of an improved algorithm that generates a metric equivalent to the general harmonic metric of that work but written in radiative coordinates, i.e. admitting an expansion in powers of r-1 for r → infinity and t - r fixed. The arbitrary parameters of the construction are the radiative multipole moments. (author)