The existence of gravitational radiation arriving at null infinity ${\mathcal{J}}^{+}$, i.e., escaping from the physical system, is addressed in the presence of a non-negative cosmological constant $\Lambda \ge 0$. The case with vanishing $\Lambda$ is well understood and relies on the properties of the News tensor field (or the News function) defined at ${\mathcal{J}}^{+}$. The situation is drastically different when $\Lambda >0$, where there is no known notion of `News’ with similar good properties. In this paper, both situations are considered jointly from a tidal point of view, that is, taking into account the strength (or energy) of the curvature tensors. The fundamental object used for this purposes is the asymptotic (radiant) super-momentum, a causal vector defined at infinity with remarkable properties. This leads to a novel characterization of gravitational radiation valid for the general case with $\Lambda \ge 0$, which has been proven to be equivalent when $\Lambda =0$ to the standard one based on News. Here, the implications of this result when $\Lambda >0$ are analyzed in detail. A general procedure to construct `News tensors’ when $\Lambda >0$ is depicted, a proposal for asymptotic symmetries is provided, and an example of a conserved charge that may detect gravitational radiation at ${\mathcal{J}}^{+}$ is exhibited. A series of illustrative examples is listed as well.

中文翻译：

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具有非负宇宙学常数的无限远引力辐射

到达零无穷处的引力辐射的存在${\mathcal{Ĵ}}^{+}$，即逃离物理系统，是在存在非负宇宙学常数的情况下解决的$\Lambda \ge 0$. 消失的情况$\Lambda$很好理解并依赖于定义的新闻张量场（或新闻函数）的属性${\mathcal{Ĵ}}^{+}$. 情况大不相同，当$\Lambda >0$，其中没有具有类似良好属性的“新闻”的已知概念。本文从潮汐的角度综合考虑这两种情况，即考虑曲率张量的强度（或能量）。用于此目的的基本对象是渐近（辐射）超动量，一个定义在无穷远处的具有显着特性的因果向量。这导致了引力辐射的新表征，适用于一般情况$\Lambda \ge 0$，这已被证明是等价的，当$\Lambda =0$到基于新闻的标准。在这里，这个结果的含义是$\Lambda >0$进行了详细分析。构建“新闻张量”的一般程序$\Lambda >0$描述了一个渐近对称性的建议，以及一个可以检测引力辐射的守恒电荷的例子${\mathcal{Ĵ}}^{+}$被展出。还列出了一系列说明性示例。