The aim of this paper is to perform stability analysis of anisotropic dissipative cylindrical collapsing model in f (R, T, R µν T µν ) gravity. In this context, the modified version of hydrodynamical equation is explored by means of dynamical equations and radial perturbation scheme. We examined the role of adiabatic index, dissipation as well as the particular cosmological model on the onset of dynamical instability of the evolving cylindrical system that was initially in hydrostatic equilibrium with Newtonian and post Newtonian approximations. It is pointed out that extra curvature terms of f (R, T, R µν T µµν ) gravity tends to increase the stability, while that heat radiations push the system to enter into unstable window. Further, our results reveal the significance of adiabatic index in the stability analysis of cylindrical celestial model.

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The aim of this paper is to investigate the stable/unstable regimes of the non-static anisotropic filamentary stellar models in the framework of f (R, T, R μν T μν ) gravity. We construct the field equations and conservation laws in the perspective of this model of gravity. The perturbation scheme is applied to the analysis of the behavior of a particular f (R, T, R μν T μν ) cosmological model on the evolution of cylindrical system. The role of the adiabatic index is also checked in the formulations of the instability regions. We have explored the instability constraints in the Newtonian and post-Newtonian limits. Our results reinforce the significance of the adiabatic index and dark source terms in the stability analysis of celestial objects in modified gravity.

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One of the feasible potential candidates for illustrating the accelerating expansion of the cosmos can be taken through the notion of modified gravity. Within the context of metric f(R) gravity, the contribution of this work features a better understanding of complexity factors for anisotropic static fluid composition in axially symmetric spacetime. This is a generalization of the work done by Herrera et al. [Phys. Rev. D 99, 044049 (2019)]. We formulate generalized dynamical and field equations for anisotropic source in our analysis. We will compute three distinct complexity factors (YTF 1, YTF 2, YTF 3) after incorporating structure scalars via orthogonal breakdown of the curvature tensor. The differential equations for the conformal tensor are assessed in terms of these complexity factors for the physical illustration. It is inferred that all these factors vanish for the matter spheroid provided with energy homogeneity and isotropic pressure. Nonetheless, the vanishing of these factors might be observed in different scenarios. This happened because energy inhomogeneity and pressure anisotropy cancel out each other in the description of complexity factors. Certain exact solutions of this nature have been reported and studied. All of the outcomes would reduce to general relativity within usual limits.