Effects of Dark Energy Perturbations on Cosmological Tests of General Relativity

Understand

Cosmological tests to distinguish between dark energy (DE) and modifications to gravity are a promising route to obtain clues on the origin of cosmic acceleration.

• We study here the robustness of these tests to the presence of DE density, velocity, and anisotropic stress perturbations.
• We find that the dispersion in the growth index parameter remains small enough to distinguish between extreme cases of DE models and some commonly used modified gravity models.
• The sign of the slope parameter for a redshift dependent growth index was found to be inconsistent as an additional test in extreme cases of DE models with perturbations.