Probing scalar-tensor-induced gravitational waves in the nHz band: NANOGrav and SKA
The study computes scalar-tensor-induced gravitational waves (STGWs) during matter-dominated and early matter-dominated phases, including a transition to radiation domination. Results show that while scalar contributions are not dominant in current nanohertz data, STGWs from an early phase can be a viable target for future detectors like SKA. This suggests STGWs are a promising source of the stochastic gravitational wave background.