Sabino Matarrese

TL;DR: In this article, the authors developed the formalism necessary to extract statistical anisotropic information from the three-point function of the CMB temperature anisotropy, and they employed a simplified vector field model and parametrized the bispectrum of curvature fluctuations in such a way that all the information about statistical aisotropic to the isotropic amplitudes was encoded in some parameters.

Abstract: The general relativistic non--linear dynamics of a self--gravitating collisionless fluid with vanishing vorticity is studied in synchronous and comoving -- i.e. {\em Lagrangian} -- coordinates. Writing the equations in terms of the metric tensor of the spatial sections orthogonal to the fluid flow allows an unambiguous expansion in inverse powers of the speed of light. The Newtonian and post--Newtonian approximations are derived in Lagrangian form; the non--linear evolution of the system on super--horizon scales, leading to the so--called ``silent universe", is also briefly discussed. A general formula for the gravitational waves generated by the non--linear evolution of cosmological perturbations is given: a stochastic gravitational--wave background is shown to be produced by non--linear cosmic structures, with present--day closure density $\Omega_{gw} \sim 10^{-5}$ -- $10^{-6}$ on the scale of 1 -- 10 Mpc.

TL;DR: In this paper, the authors comment on the recent attempt by Martineau and Brandenberger to explain the acceleration of the universe using the back-reaction of long-wavelength perturbations associated with isocurvature perturbation modes.

TL;DR: In this article, the relativistic non-linear dynamics of a self-gravitating collisionless fluid with vanishing vorticity is studied in synchronous and comoving coordinates.