Regular accelerating Universe without dark energy

TL;DR

This paper explores how torsion in Poincaré gauge gravity models can produce an accelerating universe without dark energy, including inflationary and bouncing solutions, by analyzing scalar fields and matter effects.

Contribution

It introduces a class of homogeneous isotropic models with torsion that naturally generate cosmic acceleration without dark energy, expanding the understanding of alternative gravity theories.

Findings

Effective cosmological constant arises from torsion effects.

Regular bouncing solutions are found at high energy densities.

Torsion can drive acceleration without dark energy.

Abstract

Homogeneous isotropic cosmological models with two torsion functions filled with scalar fields and usual gravitating matter are built and investigated in the framework of the Poincar\'e gauge theory of gravity. It is shown that by certain restrictions on indefinite parameters of gravitational Lagrangian the cosmological equations at asymptotics contain an effective cosmological constant that can explain observable acceleration of cosmological expansion. The behavior of inflationary cosmological solutions at extremely high energy densities is analyzed, regular bouncing solutions are obtained. The role of the space-time torsion provoking the acceleration of cosmological expansion is discussed.