Cosmographic and Matter Bounce Scenario in Modified Torsion Gravity

Abstract

This thesis is devoted to discuss cosmological implication of various setups in torsion based theories of gravity. Firstly, we investigate the cos- mological implications of a modified theory of gravity that combines the torsion scalar T and the trace of the energy-momentum tensor τ . For a flat FRW universe, we consider the functional form f (T, τ ) = ατ + γT 2, where α and γ are adjustable parameters. We examine the cosmological behavior of the deceleration parameter and the equation of state parameter, which demonstrate a transition from deceleration to acceleration. Additionally, we explore a bouncing universe scenario in modified f (T, τ ) gravity. We study two distinct scale factor models, both of which are non-zero at the point of bounce (t = 0) and can resolve the singularity problem. We present the behavior of the Hubble parameter H and the deceleration parameter q, energy conditions (null energy condition and strong energy condition) and stability of both models at the point of bounce. Secondly, we consider an- other torsion based theory named as non-zero torsion gravity to discuss the cosmographic analysis. For this purpose, the evolutions of the deceleration parameter q(z), jerk parameter j(z), snap parameter s(z), lerk parameter l(z) and EoS parameter ωD with respect to redshift z are reconstructed.