4 research outputs found
From 2-Dimensional Surfaces to Cosmological Solutions
We construct perfect fluid metrics corresponding to spacelike surfaces
invariant under a 1-dimensional group of isometries in 3-dimensional Minkowski
space. Under additional assumptions we obtain new cosmological solutions of
Bianchi type II, VI_0 and VII_0. The solutions depend on an arbitrary function
of time, which can be specified in order to satisfy an equation of state.Comment: 12 pages, no figures, LaTeX2e, to be published in Class. Quant. Gra
The Simon and Simon-Mars Tensors for Stationary Einstein-Maxwell Fields
Modulo conventional scale factors, the Simon and Simon-Mars tensors are
defined for stationary vacuum spacetimes so that their equality follows from
the Bianchi identities of the second kind. In the nonvacuum case one can absorb
additional source terms into a redefinition of the Simon tensor so that this
equality is maintained. Among the electrovacuum class of solutions of the
Einstein-Maxwell equations, the expression for the Simon tensor in the
Kerr-Newman-Taub-NUT spacetime in terms of the Ernst potential is formally the
same as in the vacuum case (modulo a scale factor), and its vanishing
guarantees the simultaneous alignment of the principal null directions of the
Weyl tensor, the Papapetrou field associated with the timelike Killing vector
field, the electromagnetic field of the spacetime and even the Killing-Yano
tensor.Comment: 12 pages, Latex IOP article class, no figure
Statistical characteristics of formation and evolution of structure in the universe
An approximate statistical description of the formation and evolution of
structure of the universe based on the Zel'dovich theory of gravitational
instability is proposed. It is found that the evolution of DM structure shows
features of self-similarity and the main structure characteristics can be
expressed through the parameters of initial power spectrum and cosmological
model. For the CDM-like power spectrum and suitable parameters of the
cosmological model the effective matter compression reaches the observed scales
20 -- 25Mpc with the typical mean separation of
wall-like elements 50 -- 70Mpc. This description can be
directly applied to the deep pencil beam galactic surveys and absorption
spectra of quasars. For larger 3D catalogs and simulations it can be applied to
results obtained with the core-sampling analysis.
It is shown that the interaction of large and small scale perturbations
modulates the creation rate of early Zel'dovich pancakes and generates bias on
the SLSS scale. For suitable parameters of the cosmological model and reheating
process this bias can essentially improve the characteristics of simulated
structure of the universe.
The models with give the best description of the
observed structure parameters. The influence of low mass "warm" dark matter
particles, such as a massive neutrino, will extend the acceptable range of
and .Comment: 20pages, 7 figures, MNRAS in pres