Dynamics of a Magnetised Bianchi I Universe with Vacuum Energy

We make use of a flat, axisymmetric Bianchi I metric to investigate the effects of a magnetic field upon the dynamics of the universe for the previously unconsidered case when the accompanying fluid is a cosmological constant and derive two new solutions to the dynamical equations for this case. We examine the behaviour of the scale factor perpendicular and parallel to the field lines, A(t) and W (t) respectively, and find the expected behaviour. The field has the strongest effect when A(t) is small, decelerating collapse perpendicular to the field lines, due to magnetic pressure, and accelerating collapse along the field lines, due to magnetic tension, while the vacuum energy dominates at late time, driving accelerated expansion. PACS numbers: 04.20.Jb, 04.40.Nr, 04.20.Dw, 98.80.Jk Submitted to: Class. Quantum Grav.