Gravitational waves in expanding universe with cosmological constant

To investigate the cosmic no hair conjecture, we numerically analyze 1-dimensional inhomogeneous space-times. The spacetimes we study are to be a plane symmetric and vacuum with a positive cosmological constant. Initially we set the inhomogeneities due to gravitational pulse waves and examine the time evolution of the Riemann invariant ⁽³⁾R_ijkl ⁽³⁾R^ijkl and Weyl curvature C_{μνρ{variant}σ} on each hypersurfaces. We find a temporal growth of the curvature in the interacting regions of waves, but the expansion of the universe later overcomes this effects. Even if we set large Riemann invariant and/or small width scale of inhomogeneity on the initial hypersurface, the nonlinearity of the gravity has little effect and the spacetime results in a flat de-Sitter spacetime.