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This report presents an in-depth review of dark energy models, focusing on their constraints in parameter space, particularly within the limit regions. It discusses the relationships between parameters, observational constraints, and the impact of corrections on model outputs. Notably, we explore how certain models, such as Park's dark energy model, behave under flat universe conditions, indicating a lack of distinction from the cosmological constant model. The findings suggest that while some regions of interest exist, observational constraints fail to encompass all predicted phenomena.
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Weekly Report Chien-I Chiang
Outline • Review • Analysis in the limit region1. 2. • Observational constraint plot
Review • Recall that the dark energy density is • The relations between the parameters are
Review • Put the above equations together we obtainwhere • I miscalculated the second term. It turns out that this correction leads to delightful result!
Review • Recall that from the model we haveThe model is consistent only ifor
Review • Also by observation we have and , which lead to • The plot considering above two constraint is shown in the next page
Analysis in the Limit Region • Consider the region in the parameter space in which is very small while is finite, i.e. • Then leads to
Analysis in the Limit Region • At , , hence • Now consider the
Analysis in the Limit Region • At , hence
Observational Constraint Plot • I used the figure in Constraints on the Phase Plane of the Dark Energy Equation of State.
Comment • I think plotting the observational constraint to 2 sigma is sufficient. It seems that even the 3-sigma contour would not cover the red region. • The model indeed have a valid region around, as we expected.
Comment • Park’s dark energy model cannot differ from usual C.C model when the universe is flat. So this model would be interesting when the red region is cover by the observational constraint. However this is not the case.