ON THE NONLINEAR ASYMPTOTICS OF TRAVELLING GRAVITATIONAL WAVES IN THE HARMONIC GAUGE

Gravitational waves are described by the Einstein equations linearized around the Minkowski metric η_μν. Writing the space-time metric in the form g_μν = η_μν + h_μν, introducing the trace-reversed perturbation and choosing the harmonic gauge □_gx^μ = 0 we get from the Einstein equations