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arXiv · 1910.00148

Luminal Propagation of Gravitational Waves in Scalar-tensor Theories: The Case for Torsion

José Barrientos·Fabrizio Cordonier-Tello·Cristóbal Corral·Fernando Izaurieta·Perla Medina·Eduardo Rodríguez·Omar Valdivia
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Abstract

Scalar-tensor gravity theories with a nonminimal Gauss-Bonnet coupling typically lead to an anomalous propagation speed for gravitational waves, and have therefore been tightly constrained by multimessenger observations such as GW170817/GRB170817A. In this paper we show that this is not a general feature of scalar-tensor theories, but rather a consequence of assuming that spacetime torsion vanishes identically. At least for the case of a nonminimal Gauss-Bonnet coupling, removing the torsionless condition restores the canonical dispersion relation and therefore the correct propagation speed for gravitational waves. To achieve this result we develop a new approach, based on the first-order formulation of gravity, to deal with perturbations on these Riemann-Cartan geometries.

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José Barrientos, Fabrizio Cordonier-Tello, Cristóbal Corral, Fernando Izaurieta, Perla Medina, Eduardo Rodríguez, Omar Valdivia. 2019-09-30. Luminal Propagation of Gravitational Waves in Scalar-tensor Theories: The Case for Torsion. https://doi.org/10.1103/physrevd.100.124039

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