Characterization of gravitational radiation at infinity with a cosmological constant

The existence or absence of gravitational radiation escaping from the spacetime at $\mathcal{J}$ is characterized in the presence of a cosmological constant $\mathrm{\Lambda }$ of any sign. To that end, the properties of the asymptotic super-momentum are used. When $\mathrm{\Lambda }=0$, the characterization is equivalent to that based on the News tensor. For $\mathrm{\Lambda }\mathrm{\ne }0$, it provides the first reliable definition of existence of radiation at $\mathcal{J}$, and it gives fully satisfactory results in known exact solutions.