Nonsingular models of universes in teleparallel theories

Area of Science:

• Cosmology
• Theoretical Physics
• General Relativity

Background:

• Teleparallel theories offer alternative frameworks to General Relativity for describing gravity.
• Understanding the universe's dynamics requires accurate models of cosmic fluids and their equations of state.

Purpose of the Study:

• To investigate the dynamics of different universe models within teleparallel theories.
• To analyze the behavior of fluids with a specific equation of state (P=-ρ-f(ρ)) in these models.
• To explore inflationary and accelerated expansion phases in nonsingular universe scenarios.

Main Methods:

• Utilizing teleparallel theories to model universe dynamics.
• Analyzing fluid behavior with the equation of state P=-ρ-f(ρ).
• Investigating two specific cases: a function f with two zeros and a pressureless fluid in loop quantum cosmology.

Main Results:

• A nonsingular universe model is obtained across different teleparallel theories and equations of state.
• Early-time inflation is achieved, mimicking a large cosmological constant.
• Late-time accelerated expansion is observed, consistent with a pressureless fluid behavior.

Conclusions:

• Teleparallel theories, combined with specific fluid equations of state, can describe a nonsingular, evolving universe.
• The models successfully reproduce key cosmic phases: inflation, matter domination, and accelerated expansion.
• The study provides a theoretical framework for understanding cosmic evolution from early inflation to late-time acceleration.