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Dark energy in Horndeski theories after GW170817: A review

6 Pith papers cite this work. Polarity classification is still indexing.

6 Pith papers citing it
abstract

The gravitational-wave event GW170817 from a binary neutron star merger together with the electromagnetic counterpart showed that the speed of gravitational waves $c_t$ is very close to that of light for the redshift $z<0.009$. This places tight constraints on dark energy models constructed in the framework of modified gravitational theories. We review models of the late-time cosmic acceleration in scalar-tensor theories with second-order equations of motion (dubbed Horndeski theories) by paying particular attention to the evolution of dark energy equation of state and observables relevant to the cosmic growth history. We provide a gauge-ready formulation of scalar perturbations in full Horndeski theories and estimate observables associated with the evolution of large-scale structures, cosmic microwave background, and weak lensing by employing a so-called quasi-static approximation for the modes deep inside the sound horizon. In light of the recent observational bound of $c_t$, we also classify surviving dark energy models into four classes depending on different structure-formation patterns and discuss how they can be observationally distinguished from each other. In particular, the nonminimally coupled theories in which the scalar field $\phi$ has a coupling with the Ricci scalar $R$ of the form $G_4(\phi) R$, including $f(R)$ gravity, can be tightly constrained not only from the cosmic expansion and growth histories but also from the variation of screened gravitational couplings. The cross correlation of integrated Sachs-Wolfe signal with galaxy distributions can be a key observable for placing bounds on the relative ratio of cubic Galileon density to total dark energy density. The dawn of gravitational-wave astronomy will open up a new window to constrain nonminimally coupled theories further by the modified luminosity distance of tensor perturbations.

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years

2026 5 2025 1

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UNVERDICTED 6

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representative citing papers

A solid unification of the dark sector

astro-ph.CO · 2026-06-25 · unverdicted · novelty 6.0

A generalized Chaplygin-type solid unifies dark matter and dark energy via an early pressureless phase transitioning to a late solid phase that supports acceleration and produces distinct low-redshift perturbation signatures.

citing papers explorer

Showing 6 of 6 citing papers.

  • Inspiral gravitational waveforms from charged compact binaries with scalar hair gr-qc · 2026-05-13 · unverdicted · none · ref 14 · internal anchor

    In Einstein-scalar-Maxwell theories, charged compact binaries produce gravitational waveforms containing a leading -1 post-Newtonian dipole correction controlled by one deviation parameter b.

  • Rotating Black Holes with Primary Scalar Hair: Shadow Signatures in Beyond Horndeski Gravity gr-qc · 2026-02-18 · unverdicted · none · ref 28 · internal anchor

    Rotating black holes with primary scalar hair in beyond Horndeski gravity produce shadows whose diameter increases for negative Q and whose distortion increases for positive Q, with EHT bounds on M87* restricting but not ruling out the (a, Q) parameter space.

  • Degenerate higher-order scalar-tensor theories in metric-affine gravity gr-qc · 2025-12-02 · unverdicted · none · ref 56 · internal anchor

    A metric-affine version of quadratic DHOST theories is derived and reduced to a one-function family that satisfies degeneracy conditions and light-speed gravitational wave propagation.

  • A solid unification of the dark sector astro-ph.CO · 2026-06-25 · unverdicted · none · ref 39 · internal anchor

    A generalized Chaplygin-type solid unifies dark matter and dark energy via an early pressureless phase transitioning to a late solid phase that supports acceleration and produces distinct low-redshift perturbation signatures.

  • Scalar-scalar-tensor interaction in DHOST theories gr-qc · 2026-06-17 · unverdicted · none · ref 14 · internal anchor

    Derives the cubic scalar-scalar-tensor interaction action for perturbations in quadratic DHOST theories on cosmological backgrounds.

  • Thermal channels of scalar and tensor waves in Jordan-frame scalar--tensor gravity gr-qc · 2026-03-28 · unverdicted · none · ref 15 · internal anchor

    Scalar and tensor perturbations in Jordan-frame scalar-tensor gravity admit an exact linear-order Eckart effective-fluid description, with gravitational-wave damping governed by the scalar sector's transverse-traceless anisotropic stress.