A simple self gravitating system—a thin spherical shell of charged pressureless matter— is naively quantized as a test case of quantum gravitational collapse. The model is interpreted in terms of an inner product on the positive energy states. An S-matrix is constructed describing scattering between negatively and positively infinite radius.

We demonstrate that a suitable coupling between a quintessence scalar field and a pressureless cold dark matter (CDM) fluid leads to a constant ratio of the energy densities of both components which is compatible with an accelerated expansion of the Universe. PACS number: 98.80.Hw

In this work, we discuss some numerical properties of the viscous numerical scheme introduced in [8] to solve the one-dimensional pressureless gases system, and study in particular, from a computational viewpoint, its asymptotic behavior when the viscosity parameter ε > 0 used in the scheme becomes smaller.

Received ; accepted – 2 – ABSTRACT We present a fitting formula for the luminosity and angular diameter distances in cosmological models with pressureless matter, a cosmological constant and zero spatial curvature. The formula has a relative error of less than 0.4% for 0.2 < Ω 0 < 1 for any redshift, and a global relative error of less than 4% for any choice of parameters.

Perturbation theory within Newtonian approximation is presented for cosmological models with varying physical constants. Analytical solutions for perturbations dynamics are obtained for each Gurzadyan-Xue model with pressureless matter and radiation. We found that perturbations grow during entire expansion within GX models, including curvatureand vacuum-dominated stage when they cease to grow i...

Porous Yb2O3 ceramic (55%) was pressureless sintered at 900°C for four hours in air. The crystal structure of confirmed to be cubic (Ia3¯) with c = 10.43731 A by neutron diffraction. ...