Quintessential Phenomena in Higher-Dimensional Space-Time

Higher-dimensional cosmology provides a natural setting to treat, at a classical level, the cosmological effects of vacuum energy. Here we discuss two situations: in the first case we start with an ordinary matter field without any equation of state and end up with a generalized Chaplygin type of gas apparently as a consequence of extra dimensions. In the second case we introduce a priori a Chaplygin type of gas to study quintessential phenomena in higher-dimensional spacetime. The first case suffers from the disqualification that no dimensional reduction occurs, which is, however, rectified in the second case. Both models show the sought-after feature of occurrence of a flip in the expansion rate. It is observed that with the increase of dimensions the occurrence of a flip is delayed in both models, more in line with current observational requirements. Interestingly, we see that, depending on some initial conditions, our model admits QCDM, Lambda CDM and also phantom-like evolution within a unified framework. Our solutions are general in nature in the sense that when the extra dimensions are switched off, the known 4D model is recovered. A correspondence to a recent work of Guo et al. on a quiessence-likemodel is also found.