Modified $f(R,T)$ theory in light of gravitational wave standard sirens

In this paper, we ponder observational constraints on the modified $f(R,T)$ gravity, where the gravitational action is a function of Ricci scalar $R$ plus the trace of the energy-momentum tensor $T$, regarding the functional form $f(R,T)=R+2f(T)$ with $f(T)=8\pi G\lambda T$. For this purpose, we utilize recently available data, including cosmic microwave background, weak lensing, supernovae, baryon acoustic oscillations, and redshift-space distortions measurements, together with forcasted gravitational wave (GW) data from Laser Interferometer Space Antenna (LISA). Notably, we examine the potentiality of simulated GW data from LISA standard sirens (SS) sources to enhance cosmological constraints on the $f(R,T)$ model parameters. In this regard, we create three LISA mock catalogs, namely Pop III, Delay, and No Delay, to improve the obtained constraints on cosmological parameters of $f(R,T)$ gravity from current observations. Numerical analysis reveals that mock GW data from LISA SS sources make marginal improvements on constraining the $f(R,T)$ model cosmological parameters.