Stability of galaxy filaments in F(R) gravity
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Date
2019-01
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UMT Lahore
Abstract
This thesis is devoted to study the dynamics of collapsing stellar ¯lament in the presences of exotic matter. We use f(R) theory to involve exotic terms in the collapsing scenario. We apply Darmois junction conditions on collapsing surface boundary and obtain the collapse equation. It is found that radial pressure associated with baryonic matter remains non zero at. We then apply two different approaches of f(R) gravity: metric f(R) gravity and Palatini f(R) approach as candidates of exotic material to explore stability criteria of the collapsing process.
Firstly, we use Starobinsky model, f(R) = R + R², then, we apply three parameter model of Palatini f(R) gravity. It is found that the stability of flamentary structure relates radial pressure of baryonic matter directly with the gravitational effects of exotic terms. Stability criteria of family of polytropic flamentary structures are discussed by applying polytropic equation of state to baryonic contribution. For all stable polytropic ¯laments, it turns out that the visible matter density is exponentially related to gravitational effects of exotic terms. Finally, we explore theoretical relation between gravitational waves and dark terms. It is theoretically predicted that the presences of exotic material can affect the propagation of gravitational waves.