Gravitational Waves from Matter Perturbations of Spectator Scalar Fields

Marcos A. G. Garcia, Angel Garcia-Vega, Sarunas Verner

We compute the stochastic gravitational wave background sourced at second order by a spectator scalar field $\chi$ coupled to the inflaton $\varphi$ through a portal interaction $\sigma {\varphi }^2{\chi }^2$ a…