Speaker
Giovanni Tambalo
(SISSA)
Description
In this talk I will discuss the classical decay of gravitational waves into dark energy fluctuations $\pi$ in the context of the EFT of Dark Energy. For cubic Horndeski and beyond Horndeski theories, the gravitational wave acts as a classical background for $\pi$ and thus modifies its dynamics. In particular, for a sufficiently large amplitude of the wave, the kinetic term of $\pi$ becomes pathological, featuring gradient and ghost instabilities. For smaller gravitational wave amplitude, $\pi$ fluctuations are described by a Mathieu equation and feature instability bands that grow exponentially. The gravitational wave signal is affected by the $\pi$ back-reaction and this provides very stringent bounds on cubic and quartic GLPV theories.
Author
Giovanni Tambalo
(SISSA)
Co-authors
Prof.
Filippo Vernizzi
(IPhT-CEA, Saclay)
Paolo Creminelli
(Scuola Normale Superiore (SNS))
Vicharit Yingcharoenrat
