Edgard C. de Rey Neto

arXiv2003

Geodesic deviation in pp-wave spacetimes of quadratic curvature gravity

We write the equation of geodesic deviations in the spacetime of $pp$-waves in terms of the Newman-Penrose scalars and apply it to study gravitational waves in quadratic curvature gravity. We show that quadratic curvature gravity $pp$-waves can have a transverse helicity-0 polarization mode and two transverse helicity-2 general relativity-like wave polarizations. A concrete example is given in which we analyze the wave polarizations of an exact impulsive gravitational wave solution to quadratic curvature gravity.

gr-qc↗

arXiv2003

A perturbative solution for gravitational waves in quadratic gravity

We find a gravitational wave solution to the linearized version of quadratic gravity by adding successive perturbations to the Einstein's linearized field equations. We show that only the Ricci squared quadratic invariant contributes to give a different solution of those found in Einstein's general relativity. The perturbative solution is written as a power series in the $β$ parameter, the coefficient of the Ricci squared term in the quadratic gravitational action. We also show that, for monochromatic waves of a given angular frequency $ω$, the perturbative solution can be summed out to give an exact solution to linearized version of quadratic gravity, for $0<ω<c/\midβ\mid^{1/2}$. This result may lead to implications to the predictions for gravitational wave backgrounds of cosmological origin.

gr-qc↗