15 papers
Isotropization of two-component fluids
Martin Goliath, Ulf S. Nilsson
We consider the problem of late-time isotropization in spatially homogeneous but anisotropic cosmological models when the source of the gravitational field consists of two non-inte…
General Relativistic Stars : Polytropic Equations of State
U. S. Nilsson, C. Uggla
In this paper, the gravitational field equations for static spherically symmetric perfect fluid models with a polytropic equation of state, , are recast into two comp…
General Relativistic Stars: Linear Equations of State
U. S. Nilsson, C. Uggla
In this paper Einstein's field equations, for static spherically symmetric perfect fluid models with a linear barotropic equation of state, are recast into a 3-dimensional regular…
Non-tilted Bianchi VII_0 models - the radiation fluid
U S Nilsson, M J Hancock, J Wainwright
We consider the late time behaviour of non-tilted perfect fluid Bianchi VII_0 models when the source is a radiation fluid, thereby completing the analysis of the Bianchi VII_0 mode…
Anisotropic universes with isotropic cosmic microwave background radiation
W C Lim, U S Nilsson, J Wainwright
We show the existence of spatially homogeneous but anisotropic cosmological models whose cosmic microwave background temperature is exactly isotropic at one instant of time but who…
A dynamical systems approach to geodesics in Bianchi cosmologies
Ulf S Nilsson, C. Uggla, J. Wainwright
To understand the observational properties of cosmological models, in particular, the temperature of the cosmic microwave background radiation, it is necessary to study their null…