Conjoined constraints on modified gravity from the expansion history and cosmic growth

Spyros Basilakos and Savvas Nesseris
Phys. Rev. D 96, 063517 – Published 18 September 2017

Abstract

In this paper we present conjoined constraints on several cosmological models from the expansion history H(z) and cosmic growth fσ8. The models we study include the CPL w0wa parametrization, the holographic dark energy (HDE) model, the time-varying vacuum (ΛtCDM) model, the Dvali, Gabadadze and Porrati (DGP) and Finsler-Randers (FRDE) models, a power-law f(T) model, and finally the Hu-Sawicki f(R) model. In all cases we perform a simultaneous fit to the SnIa, CMB, BAO, H(z) and growth data, while also following the conjoined visualization of H(z) and fσ8 as in Linder (2017). Furthermore, we introduce the figure of merit (FoM) in the H(z)fσ8 parameter space as a way to constrain models that jointly fit both probes well. We use both the latest H(z) and fσ8 data, but also LSST-like mocks with 1% measurements, and we find that the conjoined method of constraining the expansion history and cosmic growth simultaneously is able not only to place stringent constraints on these parameters, but also to provide an easy visual way to discriminate cosmological models. Finally, we confirm the existence of a tension between the growth-rate and Planck CMB data, and we find that the FoM in the conjoined parameter space of H(z)fσ8(z) can be used to discriminate between the ΛCDM model and certain classes of modified gravity models, namely the DGP and f(T).

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  • Received 24 May 2017

DOI:https://doi.org/10.1103/PhysRevD.96.063517

© 2017 American Physical Society

Physics Subject Headings (PhySH)

Gravitation, Cosmology & Astrophysics

Authors & Affiliations

Spyros Basilakos1,* and Savvas Nesseris2,†

  • 1Academy of Athens, Research Center for Astronomy and Applied Mathematics, Soranou Efesiou 4, 11527 Athens, Greece
  • 2Instituto de Física Teórica UAM-CSIC, Universidad Autonóma de Madrid, Cantoblanco, 28049 Madrid, Spain

  • *svasil@academyofathens.gr
  • savvas.nesseris@csic.es

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Vol. 96, Iss. 6 — 15 September 2017

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