Cosmological Constraints on Nonflat Exponential f(R) Gravity

• Published in: The Astrophysical journal 2022-02, Vol.926 (1), p.74
• Main Authors: Geng, Chao-Qiang, Hsu, Yan-Ting, Lu, Jhih-Rong
• Format: Article
• Language: English
• Subjects: Astronomical models; Astrophysics; Cosmological constant; Criteria; Curvature; Curved space; Dark energy; Equations of state; Flux density; Modelling; Parameters
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ac4495

We explore the viable f ( R ) gravity models in FLRW backgrounds with a free spatial curvature parameter Ω K . In our numerical calculation, we concentrate on the exponential f ( R ) model of f ( R ) = R − λ R ch ( 1 − exp ( − R / R ch ) ) , where R ch is the characteristic curvature scale, which is independent of Ω K , and λ corresponds to the model parameter, while R ch λ = 2Λ with Λ the cosmological constant. In particular, we study the evolutions of the dark energy density and equation of state for exponential f ( R ) gravity in open, flat, and closed universes, and compare with those for ΛCDM. From the current observational data, we find that λ − 1 = 0.42927 − 0.32927 + 0.39921 at 68% C.L. and Ω K = − 0.00050 − 0.00414 + 0.00420 at 95% C.L. in the exponential f ( R ) model. By using the Akaike Information Criterion, Bayesian Information Criterion, and Deviance Information Criterion, we conclude that there is no strong preference between the exponential f ( R ) gravity and ΛCDM models in the nonflat universe.