Massive gravitational waves from f(R) theories of gravity: Potential detection with LISA

TL;DR

This paper generalizes the linearization of f(R) gravity theories, revealing a third massive gravitational wave mode and discussing its potential detection with LISA.

Contribution

It introduces a generalized linearization method for all f(R) theories, uncovering a new massive gravitational wave mode and analyzing its detectability with LISA.

Findings

Every f(R) theory can be linearized to produce a massive GW mode.

The third massive mode is a general feature of f(R) theories.

Potential detection of massive GWs with LISA is feasible.

Abstract

This letter is a generalization of previous results on gravitational waves (GWs) from f(R) theories of gravity. In some previous papers, particular f(R) theories have been linearized for the first time in the literature. Now, the process is further generalized, showing that every f(R) theory can be linearized producting a third massive mode of gravitational radiation. In this framework, previous results are particular cases of the more general problem that is discussed in this letter. The potential detectability of such massive GWs with LISA is also discussed with the auxilium of longitudinal response functions.