w-cosmological singularities

Abstract

In this paper we characterize barotropic índex singularities of homogeneous isotropic cosmological models [M. P. Dabrowski and T. Denkiewicz, Phys. Rev. D 79, 063521 (2009).]. They are shown to appear in cosmologies for which the scale factor is analytical with a Taylor series in which the linear and quadratic terms are absent. Though the barotropic Índex of the perfect fluid is singular, the singularities are weak, as it happens for other models for which the density and the pressure are regular.

Quasi-rip: A new type of rip model without cosmic doomsday

“…As is well known, in [6] (see also e.g. [5,7,8]) the future singularities have been classified into four types, namely…”

“…In fact, besides the traditional Big Bang, Big Crunch, and the Big Rip, many novel singularities have been considered in the literature, such as Sudden singularities, Generalized sudden singularities, Quiescent singularities, Big Boost, Big Brake, Big Freeze, w singularities, Inaccessible singularities, Directional singularities (see e.g. [5,6] and references therein for some brief reviews). These singularities arise at the price of violation of one or several energy conditions.…”

Cosmologies with Scalar Fields from Higher Dimensions Applied to Bianchi Type VIh=-1 Model: Classical and Quantum Solutions

“…An example is the Chaplygin gas, where a proper time, characteristic to this matter, leads to the presence of singularities types I, II, III, and IV (generalizations to these models are presented in [35][36][37]) which also appear in the phantom scenario to dark/energy matter. In our case, since the matter we are considering is barotropic, initial singularities of these types do not emerge from our analysis, implying also that phantom fields are absent.…”

Singularities around w = −1

“…For instance, sudden singularities [8] and w-singularities [9] are weak singularities. They have also been studied within the framework of modified theories of gravitation [10].…”