International Journal of Modern Physics D, Vol. 10, No. 5 (2001) 741–750 c  World Scientific Publishing Company MAGNETIZED CYLINDRICALLY SYMMETRIC UNIVERSE WITH BULK VISCOSITY INDRAJIT CHAKRABARTY * Mehta Research Institute of Mathematics and Mathematical Physics, Chhatnag Road, Jhusi, Allahabad 211 019, India ANIRUDH PRADHAN † Department of Mathematics, Hindu Degree College, Zamania, Ghazipur 232 331, India N. N. SASTE Department of Mathematics, Science College, Congress Nagar, Nagpur 440 012, India Received 6 April 2000 Revised 8 October 2000 Communicated by A. Dolgov We consider a magnetic cylindrically symmetric universe with two degrees of freedom in the presence of an electrically neutral viscous fluid. The source of the magnetic field is an electric current along the x-axis. The coefficient of bulk viscosity is assumed to be a power function of the mass density. Without assuming any adhoc law, we obtain a cosmological constant as a decreasing function of time which is supported by results from recent supernovae observations. 1. Introduction Many investigations in the framework of general relativity consider isotropic and homogeneous cosmological models with a perfect fluid distribution as the source of matter. However, there is no a priori reason to assume, without any conclusive evidence, that our universe was not anisotropic at the early stages of its evolution. Furthermore, various physical phenomena like the large entropy per baryon and the remarkable degree of isotropy in the background radiation at the present epoch leads us to consider dissipative effects in cosmological problems. Viscous effects in the evolution of our universe have been ascribed to decoupling of neutrinos during the radiation era and the decoupling of matter and radiation in the recombination * E-mail: indrajitchakrabarty@usa.net, inchak@yahoo.com † E-mail: acpradhan@usa.net, acpradhan@yahoo.com Corresponding author. 741 Int. J. Mod. Phys. D 2001.10:741-750. Downloaded from www.worldscientific.com by INTER-UNIVERSITY CENTRE FOR on 06/02/14. For personal use only.