TY - JOUR

T1 - Dark energy scenario consistent with GW170817 in theories beyond Horndeski gravity

AU - Kase, Ryotaro

AU - Tsujikawa, Shinji

N1 - Funding Information:
R. K. is supported by the Grant-in-Aid for Young Scientists B of the JSPS Grant No. 17K14297. S. T. is supported by the Grant-in-Aid for Scientific Research Fund of the JSPS Grant No. 16K05359 and MEXT KAKENHI Grant-in-Aid for Scientific Research on Innovative Areas “Cosmic Acceleration” (Grant No. 15H05890).

PY - 2018/5/15

Y1 - 2018/5/15

N2 - The Gleyzes-Langlois-Piazza-Vernizzi (GLPV) theories up to quartic order are the general scheme of scalar-tensor theories allowing the possibility for realizing the tensor propagation speed ct equivalent to 1 on the isotropic cosmological background. We propose a dark energy model in which the late-time cosmic acceleration occurs by a simple k-essence Lagrangian analogous to the ghost condensate with cubic and quartic Galileons in the framework of GLPV theories. We show that a wide variety of the variation of the dark energy equation of state wDE including the entry to the region wDE<-1 can be realized without violating conditions for the absence of ghosts and Laplacian instabilities. The approach to the tracker equation of state wDE=-2 during the matter era, which is disfavored by observational data, can be avoided by the existence of a quadratic k-essence Lagrangian X2. We study the evolution of nonrelativistic matter perturbations for the model ct2=1 and show that the two quantities μ and Σ, which are related to the Newtonian and weak lensing gravitational potentials respectively, are practically equivalent to each other, such that μ≃Σ>1. For the case in which the deviation of wDE from -1 is significant at a later cosmological epoch, the values of μ and Σ tend to be larger at low redshifts. We also find that our dark energy model can be consistent with the bounds on the deviation parameter αH from Horndeski theories arising from the modification of gravitational law inside massive objects.

AB - The Gleyzes-Langlois-Piazza-Vernizzi (GLPV) theories up to quartic order are the general scheme of scalar-tensor theories allowing the possibility for realizing the tensor propagation speed ct equivalent to 1 on the isotropic cosmological background. We propose a dark energy model in which the late-time cosmic acceleration occurs by a simple k-essence Lagrangian analogous to the ghost condensate with cubic and quartic Galileons in the framework of GLPV theories. We show that a wide variety of the variation of the dark energy equation of state wDE including the entry to the region wDE<-1 can be realized without violating conditions for the absence of ghosts and Laplacian instabilities. The approach to the tracker equation of state wDE=-2 during the matter era, which is disfavored by observational data, can be avoided by the existence of a quadratic k-essence Lagrangian X2. We study the evolution of nonrelativistic matter perturbations for the model ct2=1 and show that the two quantities μ and Σ, which are related to the Newtonian and weak lensing gravitational potentials respectively, are practically equivalent to each other, such that μ≃Σ>1. For the case in which the deviation of wDE from -1 is significant at a later cosmological epoch, the values of μ and Σ tend to be larger at low redshifts. We also find that our dark energy model can be consistent with the bounds on the deviation parameter αH from Horndeski theories arising from the modification of gravitational law inside massive objects.

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U2 - 10.1103/PhysRevD.97.103501

DO - 10.1103/PhysRevD.97.103501

M3 - Article

AN - SCOPUS:85048084584

VL - 97

JO - Physical Review D

JF - Physical Review D

SN - 2470-0010

IS - 10

M1 - 103501

ER -