AT1 - Extended Theories of Gravity and Quantum Cosmology |
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Speaker |
Saridakis, Emmanuel |
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Coauthors |
Gabriel Farrugia, Jackson Levi Said, Viktor Gakis, and Yi-Fu Cai, Chunlong Li, LingQin Xue |
| Talk Title |
Gravitational Waves in Extended Teleparallel Theories |
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Abstract |
We investigate the gravitational waves and their properties in various modified teleparallel theories, such as f(T), f(T,B) and f(T,TG) gravities. We find that the speed of gravitational waves within f(T) gravity is exactly equal to the light speed, and hence the constraints from GW170817 and GRB170817A are trivially satisfied. Nevertheless, by examining the dispersion relation and the frequency of cosmological gravitational waves, we observe a deviation from the results of General Relativity, quantified by a new parameter. For non-trivial f(T,B) 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. Finally, for f(T,TG) gravity we show that at first-order perturbations the gravitational waves exhibit the same behavior to those of f(T) gravity. Since different modified teleparallel theories exhibit different gravitational wave properties, the advancing 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. |
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