ar X iv : a st ro - p h / 02 12 56 6 v 1 3 0 D ec 2 00 2 Dark Energy : Is it Q or Λ ?

ar X iv : a st ro - p h / 02 11 45 7 v 2 1 0 D ec 2 00 2 Time variation of fundamental constants : two phenomenological models

Time variation of fundamental constants, a strong signal of new physics, is analyzed comparing extant data with two phenomenological models. Results are discussed.

ar X iv : h ep - t h / 03 02 00 7 v 3 2 8 A pr 2 00 3 April 2003 Stability Issues for w < − 1 Dark Energy

Precision cosmological data hint that a dark energy with equation of state w = P/ρ < −1 and hence dubious stability is viable. Here we discuss for any w nucleation from Λ > 0 to Λ = 0 in a first-order phase transition. The critical radius is argued to be at least of galactic size and the corresponding nucleation rate glacial, thus underwriting the dark energy’s stability and rendering remote an...

ar X iv : a st ro - p h / 06 12 37 8 v 1 1 4 D ec 2 00 6 Magnetic fields , strings and cosmology

ar X iv : a st ro - p h / 02 05 42 8 v 1 2 4 M ay 2 00 2 A LATE - TIME TRANSITION IN THE EQUATION OF STATE VERSUS Λ CDM

We study a model of the dark energy which exhibits a rapid change in its equation of state w(z), such as occurs in vacuum metamorphosis. We compare the model predictions with CMB, large scale structure and supernova data and show that a late-time transition is marginally preferred over standard ΛCDM.

ar X iv : a st ro - p h / 02 12 57 9 v 1 3 1 D ec 2 00 2 Behaviour of Magnetic Tubes in Neutron Star ’ s

It is found from Maxwell's equations that the magnetic field lines are good analogues of relativistic strings. It is shown that the super-conducting current in the neutron star's interior causes local rotation of magnetic flux tubes carrying quantized flux.