Are gravitational waves being 'redshifted' away by the cosmological constant?

The theoretical framework underlying gravitational waves may have to be revamped to account for dark energy and the acceleration of the expansion of the universe. That's the conclusion of researchers in the US, who say that while gravitational waves from nearby sources will be unaffected, next-generation detectors such as the Laser Interferometer Space Antenna (LISA) and the Einstein Telescope – which aim to detect gravitational waves from billions of light-years away – may fall foul of the expansion of the universe. While such telescopes will still detect gravitational waves, the signal detected from more distant waves could be fairly different to what is currently expected, say the researchers.