Cosmological constraints of phantom dark energy models

Abstract

We address three genuine phantom dark energy models where each of them induces the particular future events known as Big Rip, Little Rip and Little Sibling of the Big Rip. The background models are fully determined by a given dark energy equation of state. We first observationally constrain the corresponding model parameters that characterise each paradigm using the available data of supernova type Ia, Cosmic Microwave Background and Baryonic Acoustic Oscillations by using a Markov Chain Monte Carlo method. The obtained fits are used to solve numerically the first order cosmological perturbations. We compute the evolution of the density contrast of (dark) matter and DE, from the radiation dominated era till a totally DE dominated universe. Then, the obtained results are compared with respect to ΛCDM. We obtain the predicted current matter power spectrum and the evolution of f σ8 given by the models studied in this work. Finally, the models are tested by computing the reduced χ 2 for the "Gold2017" f σ8 dataset. * aminebouali smp@yahoo.com †

Classical and quantum fate of the little sibling of the big rip in f(R) cosmology

“…As it was shown in reference [14], although the event takes place at infinite cosmic time in the future, the cosmological bounded structures are destroyed at a finite time scale. Furthermore, the evolution described by this model was shown to be compatible with that modelled by the ΛCDM scheme and constrained observationally in [17].…”

“…It is characterized by the divergence of the observable Universe and the expansion rate, keeping the derivative of this rate a finite value [14]. For observational constraints on this type of models see references [15][16][17]. Nonetheless, the common belief is that these singularities will be cured or avoided in the quantum realm, as it is assumed to happen with the big bang (see [11,[18][19][20] for reviews on the topic).…”

Classical and Quantum f(R) Cosmology: The Big Rip, the Little Rip and the Little Sibling of the Big Rip

“…Note that the BR model here considered is just a subcase of the more general wCDM scenario, which has been thoroughly analyzed in the literature (see, for example, references [37][38][39][40][41][42][43][44][45], among others). More importantly, these specific phantom DE models have been shown to be compatible with the current observational data; see, for instance, references [37][38][39]51,56,57,79]. Therefore, our own universe may evolve towards some of these singular fates.…”

“…See a brief summary of the phenomenology of these riplike doomsdays in Table 1. (See also references [56,57] for observational constraints on some phantom DE models leading the expansion towards these events. )…”

“…In the following, for the sake of concreteness, we shall consider the cosmological constraints obtained in reference [57] when binding those DE models with observational data. Thus, the results presented in the incoming sections are subjected to the observational constraints on the parameter A presented in reference [57]. These constraints are summarized in Table 3.…”