Phenomenology in type-I minimally modified gravity

Katsuki Aoki, Antonio De Felice, Chunshan Lin, Shinji Mukohyama, Michele Oliosi

    研究成果: Article

    抄録

    We study cosmology in a class of minimally modified gravity (MMG) with two local gravitational degrees of freedom. We classify modified gravity theories into type-I and type-II: theories of type-I have an Einstein frame and can be recast by change of variables as general relativity (GR) with a non-minimal matter coupling, while theories of type-II have no Einstein frame. Considering a canonical transformation of the lapse, the 3-dimensional induced metric and their conjugate momenta we generate type-I MMG. We then show that phenomenological deviations from GR, such as the speed of gravitational waves c T and the effective gravitational constant for scalar perturbations G eff , are characterized by two functions of an auxiliary variable. We study the phenomenology of several models all having c T =1. We obtain a scenario with c T =1 in which the effective equation-of-state parameter of dark energy is different from -1 even though the cosmic acceleration is caused by a bare cosmological constant, and we find that it is possible to reconstruct the theory on choosing a selected time-evolution for the effective dark energy component.

    元の言語English
    記事番号017
    ジャーナルJournal of Cosmology and Astroparticle Physics
    2019
    発行部数1
    DOI
    出版物ステータスPublished - 2019 1 7

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    phenomenology
    gravitation
    dark energy
    relativity
    gravitational constant
    gravitational waves
    cosmology
    equations of state
    degrees of freedom
    scalars
    deviation
    momentum
    perturbation

    ASJC Scopus subject areas

    • Astronomy and Astrophysics

    これを引用

    Phenomenology in type-I minimally modified gravity. / Aoki, Katsuki; Felice, Antonio De; Lin, Chunshan; Mukohyama, Shinji; Oliosi, Michele.

    :: Journal of Cosmology and Astroparticle Physics, 巻 2019, 番号 1, 017, 07.01.2019.

    研究成果: Article

    Aoki, Katsuki ; Felice, Antonio De ; Lin, Chunshan ; Mukohyama, Shinji ; Oliosi, Michele. / Phenomenology in type-I minimally modified gravity. :: Journal of Cosmology and Astroparticle Physics. 2019 ; 巻 2019, 番号 1.
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    abstract = "We study cosmology in a class of minimally modified gravity (MMG) with two local gravitational degrees of freedom. We classify modified gravity theories into type-I and type-II: theories of type-I have an Einstein frame and can be recast by change of variables as general relativity (GR) with a non-minimal matter coupling, while theories of type-II have no Einstein frame. Considering a canonical transformation of the lapse, the 3-dimensional induced metric and their conjugate momenta we generate type-I MMG. We then show that phenomenological deviations from GR, such as the speed of gravitational waves c T and the effective gravitational constant for scalar perturbations G eff , are characterized by two functions of an auxiliary variable. We study the phenomenology of several models all having c T =1. We obtain a scenario with c T =1 in which the effective equation-of-state parameter of dark energy is different from -1 even though the cosmic acceleration is caused by a bare cosmological constant, and we find that it is possible to reconstruct the theory on choosing a selected time-evolution for the effective dark energy component.",
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    AU - Felice, Antonio De

    AU - Lin, Chunshan

    AU - Mukohyama, Shinji

    AU - Oliosi, Michele

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    AB - We study cosmology in a class of minimally modified gravity (MMG) with two local gravitational degrees of freedom. We classify modified gravity theories into type-I and type-II: theories of type-I have an Einstein frame and can be recast by change of variables as general relativity (GR) with a non-minimal matter coupling, while theories of type-II have no Einstein frame. Considering a canonical transformation of the lapse, the 3-dimensional induced metric and their conjugate momenta we generate type-I MMG. We then show that phenomenological deviations from GR, such as the speed of gravitational waves c T and the effective gravitational constant for scalar perturbations G eff , are characterized by two functions of an auxiliary variable. We study the phenomenology of several models all having c T =1. We obtain a scenario with c T =1 in which the effective equation-of-state parameter of dark energy is different from -1 even though the cosmic acceleration is caused by a bare cosmological constant, and we find that it is possible to reconstruct the theory on choosing a selected time-evolution for the effective dark energy component.

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