New observational constraints on f(T) cosmology from radio quasars

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 Ω m obtained by quasars is much larger than that derived from other observations. For one of the models considered (f1CDM) a small but noticeable deviation from Λ CDM cosmology is present, while in the framework of f3CDM 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.