Abstract
Using a new recently compiled milliarcsecond compact radio data set of 120 intermediate-luminosity quasars in the redshift range 0.46< z <2.76, whose statistical linear sizes show negligible dependence on redshifts and intrinsic luminosity and thus represent standard rulers in cosmology, we constrain three viable and most popular f(T) gravity models, where T is the torsion scalar in teleparallel gravity. Our analysis reveals that constraining power of the quasars data (N=120) is comparable to the Union2.1 SN Ia data (N=580) for all three f(T) models. Together with other standard ruler probes such as cosmic microwave background and baryon acoustic oscillation distance measurements, the present value of the matter density parameter Omega _mathrm{m} obtained by quasars is much larger than that derived from other observations. For one of the models considered (f_1CDM) a small but noticeable deviation from Lambda CDM cosmology is present, while in the framework of f_3CDM the effective equation of state may cross the phantom divide line at lower redshifts. These results indicate that intermediate-luminosity quasars could provide an effective observational probe comparable to SN Ia at much higher redshifts, and f(T) gravity is a reasonable candidate for the modified gravity theory.
Highlights
Well, one can modify the gravity according to the scenario described by the so-called f (T ) theory [15], which was proposedin the framework of the Teleparallel Equivalent of General Relativity
In order to to make a good comparison between different models or decide which model is preferred by the observational data, we will use two standard information criteria, namely the Akaike Information Criterion (AIC) [53] and the Bayesian Information Criterion (BIC) [54] to study competing models
As an interesting approach to modify gravity, f (T ) theory based on the concept of teleparallel gravity, was proposed to explain the accelerated expansion of the Universe without the need of dark energy
Summary
One can modify the gravity according to the scenario described by the so-called f (T ) theory [15], which was proposedin the framework of the Teleparallel Equivalent of General Relativity ( known as Teleparallel Gravity). Logical application of this data set and obtained stringent constraints on both the matter density Ωm and the Hubble constant H0, which agree very with the recent Planck results. The advantage of this data set, compared with other standard rulers: BAO [30–32], clusters [33], strong lensing systems [34–36]), is that quasars are observed at much higher redshifts (z ∼ 3.0). The cosmic acceleration could be driven by the torsion instead of dark energy In this cosmological framework, the corresponding normalized Hubble parameter is. Compared with two previous f (T ) theories, this f (T ) model cannot be reduced to the Λ CDM for any value of its parameters. We estimate the f (T ) parameters by minimizing the corresponding χ2 defined as
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