Conformal (In)Equality

• Main Authors: Hyun Young-Hwan, Kim Yoonbai, Lee Seokcheon
• Format: Article
• Language: English
• Published: EDP Sciences 2018-01-01
• Series: EPJ Web of Conferences
• Online Access: https://doi.org/10.1051/epjconf/201816808001

The current accelerating expansion of the Universe is explained either by dark energy or by modified gravity theories. Both of them can explain exactly the same background evolution of the Universe, however this degeneracy may be broken when the observation of large scale structure formation is taken into account. Two observables are parameterized by the so-called dark energy equation of state, ω and the growth index parameter, γ. From these observed parameters, one may reconstruct the model parameters of the so-called scalar-tensor gravity theory, one of the modified gravity theories. Especially, the scalar-tensor gravity theory is described both in Jordan frame and in Einstein frame. If cosmological observations are interpreted in one frame, then all of the observables should also be interpreted in that frame. This explicitly shows conformal inequality of cosmological observables.