Comparative analysis of Einstein gravity and Rastall gravity for the compact objects

Abstract

The present work is devoted to investigate a new solution of anisotropic compact stars in the framework of the Rastall theory of gravity with varying cosmological constant. To deal with the field equations in the Rastall framework, we have used the Karori and Barua (KB) ansatz. The graphical investigations of obtained results, for different values of the Rastall parameter have been presented to canvass the analytical results more clearly. Interestingly, we have shown that for an appropriate limit of the Rastall coupling parameter, the usual results in General Relativity (GR) can be regained. We present a comparative analysis of our obtained solutions with the GR results and observational constraints as well and divulged that our model is in good concurrence with the observational data as compared to the GR model. The numerical values of the different physical variables for some different chosen values of the Rastall parameter have been tabulated to precisely examine the effect of the Rastall parameter. For this study, we have considered a class of compact stars viz., SAXJ1808−3658(SSI),VelaX-12, HerX-1, PSRJ1416−2230 and 4U1820−30 with radii 7.07 km, 9.99 km, 7.7 km, 10.3 km and 10 km, respectively. To check the physical acceptability of the model, we have investigated the necessary physical conditions such as energy conditions, stability of the model, hydrostatic equilibrium and compactness etc. and found that all these necessary conditions are satisfied for our system and thus the presented model is physically reasonable.