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ISRN Mathematical Physics
Volume 2012 (2012), Article ID 704612, 11 pages
http://dx.doi.org/10.5402/2012/704612
Research Article

Viscous Bianchi Type I Universe with Stiff Matter and Decaying Vacuum Energy Density

1Department of Mathematics, University of Rajasthan, Jaipur 302004, India
2Department of Mathematical Sciences, A. P. S. University, Rewa 486003, India

Received 11 April 2012; Accepted 7 May 2012

Academic Editors: S. C. Lim and M. Rasetti

Copyright © 2012 Raj Bali et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We examine homogeneous and anisotropic Bianchi type I cosmological model with viscous stiff matter and time-varying cosmological term Λ which scales with Hubble parameter H. The resulting model approaches isotropy. The cosmological term Λ relaxes to a genuine cosmological constant, and the model in the absence of bulk viscosity tends to a deSitter universe asymptotically. Our scenario presents an initial epoch with decelerating expansion followed by late-time acceleration consistent with observations. Bulk viscosity advances the accelerating phase in the model and prevents the matter density to vanish for large times.