Gravitational waves from isolated systems: Surprising consequences of a positive cosmological constant

Abstract

There is a deep tension between the well-developed theory of gravitational waves from isolated systems and the presence of a positive cosmological constant $Λ$, however tiny. In particular, even the post-Newtonian quadrupole formula, derived by Einstein in 1918, has not been generalized to include a positive $Λ$. We first explain the principal difficulties and then show that it is possible to overcome them in the weak field limit. These results also provide concrete hints for constructing the $Λ>0$ generalization of the Bondi-Sachs framework for full, non-linear general relativity.

5 pages, 1 Figure. Small revision in the Introduction on page 1 and Summary/Outlook on page 4 revised; some references added. To appear in PRL