paper

Gravitational Waves in Modified Teleparallel Theories

arXiv:1804.07365 · doi:10.1103/PhysRevD.97.124064

Abstract

We investigate the gravitational waves and their properties in various modified teleparallel theories, such as and gravities. We perform the perturbation analysis both around a Minkowski background, as well as in the case where a cosmological constant is present, and for clarity we use both the metric and tetrad language. For gravity we verify the result that no further polarization modes comparing to general relativity are present at first-order perturbation level, and we show that in order to see extra modes one should look at third-order perturbations. For non-trivial gravity, by examining the geodesic deviation equations, we show that extra polarization models, namely the longitudinal and breathing modes, do appear at first-order perturbation level, and the reason for this behavior is the fact that although the first-order perturbation does not have any effect on , it does affect the boundary term . Finally, for gravity we show that at first-order perturbations the gravitational waves exhibit the same behavior to those of gravity. Since different modified teleparallel theories exhibit different gravitational wave properties, the dvancing gravitational-wave astronomy would help to alleviate the degeneracy not only between curvature and torsional modified gravity but also between different subclasses of modified teleparallel gravities.

arXiv comment14 pages

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