M.Phil / MS
Permanent URI for this collectionhttps://repository.cuilahore.edu.pk/handle/123456789/52
This collection archives the complete set of theses produced by students of the COMSATS University Islamabad, Lahore Campus.
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Item Non-Commutative Wormholes Solutions in Rastall Like Teleparallel Gravity(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2020) Komal Rasool; SP19-RMT-020; LHR TP 6476; Dr. Rabia SaleemThe main focus of this thesis is to explore the phenomena of the traversable wormhole (TWH) solutions with non-commutative (NC) geometry using con formal symmetries in the framework of Rastall like teleparallel gravity (RTG). Togetthis, wederivethebackgroundfieldequationsforwormhole(WH)geom etry within RTG. We calculate the solution of the corresponding field equations using Gaussian and Lorentzian matter-energy distributions under conformal motion. Using both these distributions, we gain analytic WH solutions in terms of few special math functions such as gamma, exponential and hypergeometric functions. Further, we check the viability of weak, strong, and null energy conditions (ECs) for the considered fluid distribution at the WH throat and interpret them graphically. We are interested in finding the impact of an additional Rastall parameteronNCWHgeometriesascomparedtoteleparallelgravity. Moreover, weexplainthepossible constraints for the positivity of active gravitational mass in bothdistributions. We also explore the stability of gained WH solutions using the modified equilibrium condition in terms of four different forces in RTG. It is concluded that the constructed solutions are physically viable and stable.Item Inflationary and Accelerating Cosmic Solutions in Rastall Gravity(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Muhammad Waheed Zafar; SP19-RMT-011; LHR TP 6471; Dr. Rabia SaleemThe main focus of this thesis is to investigate accelerating expansion of our universe in the framework of Rastall theory of gravity (RTG) using non-linear inhomogeneousequationofstate(EoS)forFriedmann-Robertson-Walker(FRW) model. First we findthesolution of Hubble parameter, energy density and scale factor investigating the transition from non-phantom to phantom era. We study transition towards superaccelerating phase, i.e., the case when third derivative of the scale factor is positive. We find present and future singularity for our model. Second to check the thermodynamical evolution of cosmos, we find the product of temperature and entropy (TdS), and observe it graphically. To check the nature of cosmos, we find some important cosmological parameters using obtained solutions including deceleration, jerk, variable jerk, gradually varying jerk and snap parameters. Through detailed graphical analysis, we found that RTGis a good candidate to represent accelerating cosmic expansion.