Gravitational waves from compact sources in a de Sitter background

The concordance model of cosmology favors a universe with a tiny positive cosmological constant. A tiniest positive constant curvature profoundly alters the asymptotic structure, forcing a relook at a theory of gravitational radiation. Even for compact astrophysical sources, the intuition from Minkowski background is challenged at every step. Nevertheless, at least for candidate sources such as compact binaries, it is possible to quantify the influence of the cosmological constant, as small corrections to the leading order Minkowski background results. Employing suitably chosen Fermi normal coordinates in the static patch of the de Sitter background, we compute the field due to a compact source to first order in Lambda For contrast, we also present the field in the Poincare patch where the leading correction is of order root Lambda. We introduce a gauge invariant quantity, deviation scalar, containing polarization information and compute it in both charts for a comparison.