A bstract We study the gravitational wave memory effect in spacetimes related to flat space by a conformal transformation. The discussion is general but length scale assumed be small compared with background curvature radius. formulas are applied Friedmann-Robertson-Walker metrics of all spatial curvatures. new terms stemming from potentially detectable future measurements.

Starting from a 6-dimensional nilpotent Lie group N endowed with an invariant SU(3) structure, we construct a homogeneous conformally parallel G2-metric on an associated solvmanifold. We classify all half-flat SU(3) structures that endow the rank-one solvable extension of N with a conformally parallel G2 structure. By suitably deforming the SU(3) structures obtained, we are able to describe the...