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 Stellar Structures in modified gravity based on Karmarkar Condition(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2020) Allah Ditta; FA18-RMT-045; LHR TP 6025; Dr. Muhammad ZubairUniverse expansion has been a hot topic of discussion since the last decade. Not long ago, it remained in discussion under ways of interest like, radiation era ( early-time expansion) also known inflationary (rapid expansion) era, late time cosmic expansion (dark energy) era etc. Thesis understudy discusses the acceleration phenomenon of the Universe in cosmology by narrating different configurations of compactobjects bytakingintoaccountthefluidofanisotropic. Here we use f(T) gravity, which is originally a real and approximate modifica tion of TEGR. We carry our study with a well-known models f(T) = βTn and f(T) = T − α (T 6 )m1 + β(T 6 )m2 of f(T) gravity where T is torsion scalar, α, β are real constant, and n,m1,m2 are integers greater or equal to 2. For the con struction of stellar structures, we use spherically symmetric space-time as it is considerably near to nature. Embedding class one approach which is famous as Karmarkar condition is a useful technique to evaluate the metric components. This techniquelinks bothofthepotentialcomponentsofthemetricfunctioninto a unified differential equation. We assume the grr component of the space-time with the required potential. Using the Karmarker condition, one can fond the gtt component of metric function by solving the differential equation which links the gravitational metric potentials. We calculate the values of constants used in modeling by comparison of interior and exterior space-times through junc tion condition. For this motive, we utilize the observed data of compact star PSRJ1614-2230 for values of radius and mass. We ensure the stability and vi ability of our model through a detailed and comprehensive inspection of TOV ix equation, EOS, speeds of sound, casualty conditions, Redshift, compactness, and mass function graphically.