A short review on clustering dark energy

Understand

We review dark energy models which can present non-negligible fluctuations on scales smaller than Hubble radius.

• Both linear and nonlinear evolutions of dark energy fluctuations are discussed.
• The linear evolution has a well-established framework, based on linear perturbation theory in General Relativity, and is well studied and implemented in numerical codes.
• We highlight the main results from linear theory to explain how dark energy perturbations become important on the scales of interest for structure formation.