Quasinormal Modes of Black Holes with Non-Linear-Electrodynamic sources in Rastall Gravity

One of the notable modifications of General Relativity (GR) is the Rastall gravity. We have studied the polarization modes of Gravitational Waves (GWs) in this gravity. It is found that at a very far distance away from the source of GWs, Rastall gravity behaves identically to GR. That is, we get only two massless tensor polarization modes of GWs in the theory. Afterwards, we have extended our study to quasinormal modes of black holes in Rastall gravity in presence of non-linear electrodynamic sources. Here the impacts of cosmological field, dust field, phantom field, quintessence field and radiation field on the quasinormal modes in presence of electrodynamic sources have been investigated. Apart from this, we have also checked the dependency of quasinormal modes with the Rastall parameter $\lambda$, black hole structural constant $N_s$ and charge of the black hole $Q$. The study shows that the quasinormal modes corresponding to the black hole with non-linear electrodynamic sources show significant deviations from a general charged black hole in Rastall gravity under certain conditions. Further, the behaviour of black holes and hence the quasinormal modes depend on the type of surrounding field considered.