科研之友
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摘要
As an important candidate gravity theory alternative to dark energy, a class of f (R) modified gravity, which introduces a perturbation of the Ricci scalar R in the EinsteinHilbert action, has been extensively applied to cosmology to explain the acceleration of the universe. In this paper, we focus on the recently-released VLBI observations of the compact structure in intermediate-luminosity quasars combined with the angular-diameterdistance measurements from galaxy clusters, which consists of 145 data points performing as individual cosmological standard rulers in the redshift range 0.023 <= z <= 2.80, to investigate observational constraints on two viable models in f (R) theories within the Palatini formalism: f(1)(R) = R-a/R-b and f(2)(R) = R - aR/R+ab. We also combine the individual standard ruler data with the observations of CMB and BAO, which provides stringent constraints. Furthermore, two model diagnostics, Om (z) and statefinder, are also applied to distinguish the two f (R) models and Lambda CDM model. Our results show that (1) The quasars sample performs very well to place constraints on the two f (R) cosmologies, which indicates its potential to act as a powerful complementary probe to other cosmological standard rulers. (2) The Lambda CDM model, which corresponds to b = 0 in the two f (R) cosmologies is still included within 1 sigma range. However, there still exists some possibility that Lambda CDM may not the best cosmological model preferred by the current high-redshift observations. (3) Given the current standard ruler data, the information criteria indicate that the cosmological constant model is still the best one, while the f(1)(R) model gets the smallest observational support. (4) The f(2)(R) model, which evolves quite different from f(1)(R) model at early times, still significantly deviates from both f(1)(R) and Lambda CDM model at the present time.
- 出版日期2018-6
- 单位北京师范大学
