Phenomenology of $\Lambda$-CDM model: a possibility of accelerating Universe with positive pressure

Abstract

Among various phenomenological $\Lambda$ models, a time-dependent model $\dot{\Lambda }\sim H^3$ is selected here to investigate the $\Lambda$-CDM cosmology. Using this model the expressions for the time-dependent equation of state parameter $\omega$ and other physical parameters are derived. It is shown that in $H^3$ model accelerated expansion of the Universe takes place at negative energy density, but with a positive pressure. It has also been possible to obtain the change of sign of the deceleration parameter $q$ during cosmic evolution.

16 Latex pages, 11 figures, Considerable modifications in the text; Accepted in IJTP

References in corpus (5)

• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• The Supernova Legacy Survey: Measurement of Omega_M, Omega_Lambda and w from the First Year Data Set
• $\Lambda$-CDM Universe: A Phenomenological Approach With Many Possibilities
• Anti-Gravitation
• Cosmological models with Gurzadyan-Xue dark energy

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