Gravitational wave birefringence in spatially curved teleparallel cosmology

We study tensor perturbations around the most general cosmologically symmetric backgrounds in a class of teleparallel gravity theories known as New General Relativity. These theories comprise a one -parameter class, which is fully consistent with observations at the post-Newtonian level, and which contains the teleparallel equivalent of General Relativity as a special case. We find that for a particular class of cosmological background geometries these theories exhibit gravitational wave birefringence and dispersion, i.e., the dispersion relation for gravitational waves depends on their polarization and wave number. The strength of this effect is directly related to the spatial curvature of the cosmological background and the parameter describing the deviation of the theory from General Relativity. We discuss the possibility of observing this effect in gravitational wave experiments. (C) 2022 The Author(s). Published by Elsevier B.V.

Automated summary

This study investigates tensor perturbations around the most general cosmologically symmetric backgrounds in a class of teleparallel gravity theories known as New General Relativity. The findings reveal the existence of gravitational wave birefringence and dispersion in these theories for a particular class of cosmological background geometries. The strength of this effect is determined by the spatial curvature of the cosmological background and the deviation parameter from General Relativity. The possibility of observing this effect in gravitational wave experiments is discussed.