Quantum treatment and equation of state of a Friedmann-Robertson-Walker brane embedded in a five dimensional fluid bulk

In the present paper, we deal with the five dimensional warped k=0–FRW Universe, with a perfect fluid in the bulk. By solving the Einstein’s Equations, we get the corresponding scale function, a, and the warp factor. Particular attention is given to the effective potential V(a), which is used in solving both the Wheeler-DeWitt equation and the stationary Schrödinger equation. Inspired by similar considerations carried out in a series of recent papers, we assume that the brane matter is made of two interacting perfect fluids. We compute the corresponding densities and pressures and write down the Equation of State, whose dynamic parameter is taking all the intermediate values, from w=1, at t=0, to w=?1, in the far future.     

Approximative analytic study of fermions in magnetar’s crust; ultra-relativistic plane waves, Heun and Mathieu solutions and beyond

Working with a magnetic field periodic along Oz and decaying in time, we deal with the Dirac-type equation characterizing the fermions evolving in magnetar’s crust. For ultra-relativistic particles, one can employ the perturbative approach, to compute the conserved current density components. If the magnetic field is frozen and the magnetar is treated as a stationary object, the fermion’s wave function is expressed in terms of the Heun’s Confluent functions. Finally, we are extending some previous investigations on the linearly independent fermionic modes solutions to the Mathieu’s equation and we discuss the energy spectrum and the Mathieu Characteristic Exponent.     

Solutions for Massless Bosons in the Mannheim-Kazanas Space-Time

Astrophysics - The present paper deals with the Mannheim-Kazanas metric which is supposed to offer a reliable explanation on the observed galaxy rotation curves. The effective potential and the...     

Five-dimensional anti-de Sitter bulk with oscillating Friedmann–Robertson–Walker branes

We propose a toy model for the five dimensional warped FRW universe of zero spatial curvature, with a stiff matter source in the bulk, whose scale function corresponds to an oscillating brane, with negative acceleration parameter. By considering the matter in the four-dimensional brane as being composed of two coupled perfect fluids, we discuss the form of the interacting term allowing energy exchange between the two fluids. Finally, special attention is given to three cases related to the chronology of the universe and the corresponding densities and pressures are calculated, pointing out non-trivial contributions coming from the fifth dimension.