Cosmological perturbations in an effective and genuinely phantom dark energy Universe

Understand

We carry out an analysis of the cosmological perturbations in general relativity for three different models which are good candidates to describe the current acceleration of the Universe.

• These three set-ups are described classically by perfect fluids with a phantom nature and represent deviations from the most widely accepted $\Lambda$CDM model.
• In addition, each of the models under study induce different future singularities or abrupt events known as (i) Big Rip, (ii) Little Rip and (iii) Little Sibling of the Big Rip.
• Only the first one is regarded as a true singularity since it occurs at a finite cosmic time.