# Cosmological viability conditions for f(T) dark energy models

## Abstract

Recently f(T) modified teleparallel gravity where T is the torsion scalar has been proposed as the natural gravitational alternative for dark energy. We perform a detailed dynamical analysis of these models and find conditions for the cosmological viability of f(T) dark energy models as geometrical constraints on the derivatives of these models. We show that in the phase space exists two cosmologically viable trajectory which (i) The universe would start from an unstable radiation point, then pass a saddle standard matter point which is followed by accelerated expansion de sitter point. (ii) The universe starts from a saddle radiation epoch, then falls onto the stable matter era and the system can not evolve to the dark energy dominated epoch. Finally, for a number of f(T) dark energy models were proposed in the more literature, the viability conditions are investigated.

- Authors:

- Department of Science, University of Kurdistan, Sanandaj (Iran, Islamic Republic of)

- Publication Date:

- OSTI Identifier:
- 22279815

- Resource Type:
- Journal Article

- Journal Name:
- Journal of Cosmology and Astroparticle Physics

- Additional Journal Information:
- Journal Volume: 2012; Journal Issue: 11; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1475-7516

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; COSMOLOGY; DE SITTER GROUP; DE SITTER SPACE; EXPANSION; GRAVITATION; NONLUMINOUS MATTER; PHASE SPACE; SCALARS; TORSION; UNIVERSE

### Citation Formats

```
Setare, M.R., and Mohammadipour, N., E-mail: rezakord@ipm.ir, E-mail: N.Mohammadipour@uok.ac.ir.
```*Cosmological viability conditions for f(T) dark energy models*. United States: N. p., 2012.
Web. doi:10.1088/1475-7516/2012/11/030.

```
Setare, M.R., & Mohammadipour, N., E-mail: rezakord@ipm.ir, E-mail: N.Mohammadipour@uok.ac.ir.
```*Cosmological viability conditions for f(T) dark energy models*. United States. doi:10.1088/1475-7516/2012/11/030.

```
Setare, M.R., and Mohammadipour, N., E-mail: rezakord@ipm.ir, E-mail: N.Mohammadipour@uok.ac.ir. Thu .
"Cosmological viability conditions for f(T) dark energy models". United States. doi:10.1088/1475-7516/2012/11/030.
```

```
@article{osti_22279815,
```

title = {Cosmological viability conditions for f(T) dark energy models},

author = {Setare, M.R. and Mohammadipour, N., E-mail: rezakord@ipm.ir, E-mail: N.Mohammadipour@uok.ac.ir},

abstractNote = {Recently f(T) modified teleparallel gravity where T is the torsion scalar has been proposed as the natural gravitational alternative for dark energy. We perform a detailed dynamical analysis of these models and find conditions for the cosmological viability of f(T) dark energy models as geometrical constraints on the derivatives of these models. We show that in the phase space exists two cosmologically viable trajectory which (i) The universe would start from an unstable radiation point, then pass a saddle standard matter point which is followed by accelerated expansion de sitter point. (ii) The universe starts from a saddle radiation epoch, then falls onto the stable matter era and the system can not evolve to the dark energy dominated epoch. Finally, for a number of f(T) dark energy models were proposed in the more literature, the viability conditions are investigated.},

doi = {10.1088/1475-7516/2012/11/030},

journal = {Journal of Cosmology and Astroparticle Physics},

issn = {1475-7516},

number = 11,

volume = 2012,

place = {United States},

year = {2012},

month = {11}

}