104 citations · 304 across the 9 of their papers we have counts for
9 papers
On average properties of inhomogeneous fluids in general relativity III: general fluid cosmologies
Thomas Buchert, Pierre Mourier, Xavier Roy
We investigate effective equations governing the volume expansion of spatially averaged portions of inhomogeneous cosmologies in spacetimes filled with an arbitrary fluid. This wor…
Cosmological backreaction and its dependence on spacetime foliation
Thomas Buchert, Pierre Mourier, Xavier Roy
The subject of cosmological backreaction in General Relativity is often approached by coordinate-dependent and metric-based analyses. We present in this letter an averaging formali…
On the 1+3 Formalism in General Relativity
Xavier Roy
We present in this paper the formalism for the splitting of a four-dimensional Lorentzian manifold by a set of time-like integral curves. Introducing the geometrical tensors charac…
xPand: An algorithm for perturbing homogeneous cosmologies
Cyril Pitrou, Xavier Roy, Obinna Umeh
In this paper, we develop in detail a fully geometrical method for deriving perturbation equations about a spatially homogeneous background. This method relies on the 3+1 splitting…
Relativistic cosmological perturbation scheme on a general background: scalar perturbations for irrotational dust
Xavier Roy, Thomas Buchert
In standard perturbation approaches and N-body simulations, inhomogeneities are described to evolve on a predefined background cosmology, commonly taken as the homogeneous-isotropi…
Global gravitational instability of FLRW backgrounds - interpreting the dark sectors
Xavier Roy, Thomas Buchert, Sante Carloni +1
The standard model of cosmology is based on homogeneous-isotropic solutions of Einstein's equations. These solutions are known to be gravitationally unstable to local inhomogeneous…