An extended analysis for a generalized Chaplygin gas model

Abstract

In this work, we have extended the analysis on the generalized Chaplygin gas (GCG) model as the unification of dark energy and dark matter. Specifically, we have shown that the model of our consideration known as the new generalized Chaplygin gas (NGCG) model, admits a scalar field description, which means that there exist a minimally coupled scalar field for a given scalar field potential where the equation of state is that of the NGCG. With the use of the later property we can construct the slow-roll parameters and derive the corresponding values for the spectral indices for the tensor to scalar perturbation and for the density perturbations. We have also analyzed the behavior of the NGCG model at the perturbation level. In particular, we have studied the growth rate of matter perturbations in terms of evolution of the linear matter density contrast. Using the growth rate data, we then compared our results with the predictions of the concordance ΛCDM and GCG models. Finally, with a view to put the NGCG model on a firm theoretical ground, we have studied the implications of gravitational thermodynamics with the dynamical apparent horizon as the causal boundary. In particular, we have studied the viability of the generalized second law of thermodynamics by assuming that the dynamical apparent horizon in a NGCG universe is endowed with Hawking temperature and Bekenstein entropy.

Evolution of perturbations in a universe with exotic solid-like matter

“…It can describe quintessence models of dark energy [11][12][13] through different approaches, including nonminimal coupling to gravity [14][15][16], kessence [17][18][19] and the Chaplygin gas [20]. Scalar field can also drive the inflation [21][22][23], it can be used in models alternative to inflation [24][25][26], describe dark matter [27,28], or both dark matter and dark energy at the same time [29][30][31]. A natural extension of single field models is the multifield approach, which is usually studied in inflationary context [32][33][34][35][36][37][38][39][40][41].…”