Observational constraints on $f(T)$ theory

Abstract

The $f(T)$ theory, which is an extension of teleparallel, or torsion scalar $T$, gravity, is recently proposed to explain the present cosmic accelerating expansion with no need of dark energy. In this Letter, we first perform the statefinder analysis and $Om(z)$ diagnostic to two concrete $f(T)$ models, i.e., $f(T)=\alpha (-T{)}^n$ and $f(T)=-\alpha T(1-e^{p{T}_0/T})$, and find that a crossing of phantom divide line is impossible for both models. This is contrary to an existing result where a crossing is claimed for the second model. We, then, study the constraints on them from the latest Union 2 Type Ia Supernova (Sne Ia) set, the baryonic acoustic oscillation (BAO), and the cosmic microwave background (CMB) radiation. Our results show that at the 95% confidence level ${\Omega }_{m0}=0.272_{-0.032}^{+0.036}$, $n=0.04_{-0.33}^{+0.22}$ for Model 1 and ${\Omega }_{m0}=0.272_{-0.034}^{+0.036}$, $p=-0.02_{-0.20}^{+0.31}$ for Model 2. A comparison of these two models with the $\Lambda$CDM by the ${\chi }_{Min}^2/dof$ (dof: degree of freedom) criterion indicates that $\Lambda$CDM is still favored by observations. We also study the evolution of the equation of state for the effective dark energy in the theory and find that Sne Ia favors a phantom-like dark energy, while Sne Ia + BAO + CMB prefers a quintessence-like one.

15 pages, 5 figures; statefinder diagnostic added, Om(z) analysis added; references added; accepted by PLB

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Cited by in corpus (13)

• Cosmological perturbations in f(T) gravity
• f(T) gravity mimicking dynamical dark energy. Background and perturbation analysis
• Generalizations of teleparallel gravity and local Lorentz symmetry
• $f(T)$ models with phantom divide line crossing
• Degrees of freedom of $f(T)$ gravity
• Growth factor in f(T) gravity
• Observational information for f(T) theories and Dark Torsion
• Conformal transformation in $f(T)$ theories
• Static Solutions with Spherical Symmetry in f(T) Theories
• Emergent universe in chameleon, f(R) and f(T) gravity theories
• Accelerating cosmology in F(T) gravity with scalar field
• Exploring the Latest Union2 SNIa Dataset by Using Model-Independent Parametrization Methods
• Parametrization for the Scale Dependent Growth in Modified Gravity