Mimicking Dark Energy with the backreactions of gigaparsec inhomogeneities

Understand

Spatial averaging and time evolving are non-commutative operations in General Relativity, which questions the reliability of the FLRW model.

• The long standing issue of the importance of backreactions induced by cosmic inhomogeneities is addressed for a toy model assuming a peak in the primordial spectrum of density perturbations and a simple CDM cosmology.
• The backreactions of initial Hubble-size inhomogeneities are determined in a fully relativistic framework, from a series of simulations using the BSSN formalism of numerical relativity.
• In the FLRW picture, these backreactions can be effectively described by two so-called morphon scalar fields, one of them acting at late time like a tiny cosmological constant.