Non-zero torsion and late cosmology

Abstract

In this work, we study some thermodynamical aspects associated with torsion in a flat FLRW spacetime cosmic evolution. By implementing two Ansatze for the torsion term, we find that the model admits a phantom regime or a quintessence behavior. This scheme differs from the CDM model at the thermodynamical level. The resulting cosmic expansion is not adiabatic, the fulfillment of the second law of thermodynamics requires a positive torsion term, and the temperature of the cosmic fluid is always positive. The entropy of the torsion phantom scenario is negative, but introducing chemical potential solves this issue. For a Dirac-Milne type Universe, the torsion leads to a growing behavior for the temperature of the fluid but has no incidence on the rate of expansion.

Torsion and shear effect on a Big Rip model in a gravitational field

“…This means that acceleration can be a geometric source in GR cosmology with torsion and shear forces. There is general agreement that the universe has reached a state of accelerating expansion at redshift z t = 0.5 (Cunha and Lima 2008;Cunha 2009). We can observe that the accelerating expansion in our model begins at q = 0, z t = 0.51, T s = 0.25, and = 0.10.…”

“…4. Note that the rapid development begins at z t = 0.51, which is consistent with the observational data, where the cosmological observations for the transition redshift of the hurrying expansion are given by 0.3 < z t < 0.8 (Riess et al 2007;Cunha and Lima 2008;Frieman et al 2008;Ishida et al 2008;Cunha 2009;Pandolfi 2009;Lima et al 2010;Li et al 2011). In Fig.…”

“…It thus becomes the source of convolution with more general prescriptions. One example is based on well-established studies of gravity, Einstein-Cartan-Keppel-Siyama (ECKS) theory (Lu and Chee 2016;Pereira et al 2019;Cruz et al 2020). In the past few years the recently revised far-parallel gravity theory has become an area of intensive research.…”

Cosmological inflation driven by a scalar torsion function

“…Henceforth, the conformal time a(η)dη = dt, will be assumed. The perturbed metric (22) leads to the following components of the linearized Einstein equations:…”

“…Motivated by these latest works, Pereira et al [14] have assumed more general expressions to torsion function, some of them proportional to matter density and other free parameters, and analyzed the constraints of the free parameters with current observational data in order to reproduce the current accelerated expansion of the universe. Even more recently, the works [19][20][21][22] explored low-redshift constraints by weak torsion field, modified torsion field, distinction between torsion and the dark sector, and late time cosmology by torsion effects, respectively, all in FRW cosmological scenarios.…”