Some Bianchi Type I Magnetized Bulk Viscous Fluid Tilted Cosmological Models

Expanding Bianchi type I magnetized bulk viscous models with two tilted fluid filled with disordered radiation and heat conduction are investigated. Here we assume a linear relation between shear and expansion, which leads to A=BC, where A, B, C are metric potentials. The coefficient of bulk viscosity is assumed to be power function of mass density. It has been shown that tilted nature of the model is preserved due to magnetic field. The various physical and geometrical properties of the models are discussed. The nature of the models in presence and absence of magnetic field and bulk viscosity are also discussed. Key words: Cosmology; Bianchi type I universe; Tilted models; Bulk viscosity

Termodinamika ravninsko-simetričnog nehomogenog svemira u općoj teoriji relativnosti

Thermodynamics of plane-symmetric inhomogeneous cosmological models of perfect fluid distribution with electromagnetic field is studied. The source of magnetic field is due to an electric current produced along z-axis. F12 is the non-vanishing component of the electromagnetic field tensor. The free gravitational field is assumed to be Petrov type-II non-degenerate. We study the thermodynamical properties of plane-symmetric inhomogeneous universe. Some physical aspects of the models are discussed and the entropy distribution is given explicity.Proučavamo termodinamiku ravninsko-simetričnih kozmoloških modela s perfektnom raspodjelom tekućine i elektromagnetskim poljem. Izvor magnetskog polja je električna struja u smjeru z-osi. Jedina komponenta elektromagnetskog tenzora polja je F12. Pretpostavlja se nedegenerirano slobodno gravitacijsko polje Petrova tipa II. Proučavamo termodinamička svojstva ravninsko-simetričnog nehomogenog svemira. Raspravljaju se neke fizikalne osobine modela, a raspodjela entropije daje se eksplicitno

Some Bianchi Type I Magnetized Bulk Viscous Fluid Tilted Cosmological Models

Abstract. Expanding Bianchi type I magnetized bulk viscous models with two tilted fluid filled with disordered radiation and heat conduction are investigated. Here we assume a linear relation between shear and expansion i.e. σ θ =constant, which leads to A=BC, where A, B, C are metric potentials. The coefficient of bulk viscosity is assumed to be power function of mass density. It has been shown that tilted nature of the model is preserved due to magnetic field. The various physical and geometrical properties of the models are discussed. The nature of the models in presence and absence of magnetic field and bulk viscosity are also discussed. Key words: Cosmology; Bianchi type I universe; Tilted models; Bulk viscosity. Introduction Many cosmologists believe that the standard cosmological models are too restrictive because of their insistence on isotropy. Several attempts have been made to study nonstandard (anisotropic) cosmological models (Narlikar [1],MacCallum [2]). It would therefore be fruitful to carry out detailed studies of gravitational fields which can be described by spacetimes of various Bianchi types. Viscosity plays an important role in explaining many physical features of the homogeneous world models. Since viscosity counteracts the cosmological collapse, a different picture of the early universe may appear due to dissipative processes caused by viscosity. Homogeneous cosmological models filled with viscous fluid have been widely studied. Murphy [3] possessed on interesting feature in that the big-bang type of singularity of infinite space time curvature does not occur to be a finite past. However, the relationship assumed by Murphy between the viscosity coefficient and the matter density is not acceptable at large density. Roy and Prakash [4] have obtained some viscous fluid cosmological models of plane symmetry. It is also well known that the presence of strong magnetic field is exhibited by galaxies and interstellar space and give rise to a kind of viscous effect in the fluid flow. The effect of bulk viscosity on the cosmological evolution has been investigated by a number of authors in framework of general theory of relativity (Padmanabhan and Chitr