Accelerating Expansion of the Universe
Writambhara Chakraborty

TL;DR
This thesis explores various cosmological models, including modified Chaplygin gas, scalar fields, and Brans-Dicke theory, to explain the universe's accelerated expansion observed through supernova measurements.
Contribution
It introduces a new inhomogeneous Chaplygin gas model capable of explaining w=-1 crossing and investigates multiple interaction scenarios with scalar and tachyonic fields.
Findings
Inhomogeneous Chaplygin gas model explains w=-1 crossing.
Scalar field interactions influence cosmic acceleration.
Brans-Dicke theory with variable can produce acceleration.
Abstract
This thesis concentrates on the accelerated expansion of the Universe recently explored by measurements of redshift and luminosity-distance relations of type Ia Supernovae. We have considered a model of the universe filled with modified Chaplygin gas and barotropic fluid. The role of dynamical cosmological constant has been explored with Modified Chaplygin Gas as the background fluid. Various phenomenological models for \Lambda have been studied in presence of the gravitational constant G to be constant or time dependent. A new form of the well known Chaplygin gas model has been presented by introducing inhomogeneity in the EOS. This model explains w=-1 crossing. An interaction of this model with the scalar field has also been investigated through a phenomenological coupling function. Tachyonic field has been depicted as dark energy model to represent the present acceleration of the…
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Taxonomy
TopicsCosmology and Gravitation Theories · Solar and Space Plasma Dynamics · Geophysics and Gravity Measurements
