Testing gravity theories with cosmic microwave background in the degenerate higher-order scalar-tensor theory

Abstract

We study the cosmic microwave background (CMB) in the framework of the degenerate higher-order scalar-tensor (DHOST) theory to test gravity theories. This theoretical framework includes the wide class of dark energy models such as the Horndeski theory and its extensions as certain limits, and the general relativity can be also recovered. In this study, to test gravity theories with CMB, we formulate the linear perturbations of gravity and matter in the theory and their effective description parameterised by time-dependent effective field theory (EFT) parameters, ${\alpha }_i$ $(i=B,K,T,M,H,L)$ and ${\beta }_i$ $(i=1,2,3)$. Based on the resultant DHOST framework, we develop a numerical code to solve Boltzmann equations consistently. We then show that the angular power spectra of the CMB temperature anisotropies, E-mode and lensing potential as a demonstration and find that the parameter characterising the DHOST theory, ${\beta }_1$, provides the larger modifications of the spectra, compared with other EFT parameters. We also show the results in the case of a specific model in which the cosmic expansion as well as the EFT parameters are consistently determined.

19 pages, 5 figures, 1 table

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Cited by in corpus (11)

• New constraints on cosmological modified gravity theories from anisotropic three-point correlation functions of BOSS DR12 galaxies
• Effective description of generalized disformal theories
• CMB constraints on DHOST theories
• Multi-component DHOST analysis in galaxy clusters
• UV sensitive one-loop matter power spectrum in degenerate higher-order scalar-tensor theories
• Testing gravity with the cosmic microwave background: constraints on modified gravity with two tensorial degrees of freedom
• DHOST gravity in Ultra-diffuse galaxies -- Part II: NGC 1052-DF4 and Dragonfly 44
• Second-order peculiar velocity field as a novel probe of scalar-tensor theories
• Recent Developments in Degenerate Higher Order Scalar Tensor Theories
• PPN meets EFT of dark energy: Post-Newtonian approximation in higher-order scalar-tensor theories
• DHOST gravity in Ultra-diffuse galaxies -- Part I: the case of NGC1052-DF2