Scalar-tensor theories and modified gravity in the wake of GW170817

By D. Langlois, R. Saito, D. Yamauchi, K. Noui. 2017

220 citations recorded by the source corpus.

Theories of dark energy and modified gravity can be strongly constrained by astrophysical or cosmological observations, as illustrated by the recent observation of the gravitational wave event GW170817 and of its electromagnetic counterpart GRB 170817A, which showed that the speed of gravitational waves, ${c}_{g}$, is the same as the speed of light, within deviations of order ${10}^{\ensuremath{-}15}$. This observation implies severe restrictions on scalar-tensor theories, in particular theories whose action depends on second derivatives of a scalar field. Working in the very general framework of degenerate higher-order scalar-tensor (DHOST) theories, which encompass Horndeski and beyond Horndeski theories, we present the DHOST theories that satisfy ${c}_{g}=c$. We then examine, for these theories, the screening mechanism that suppresses scalar interactions on small scales, namely the Vainshtein mechanism, and compute the corresponding gravitational laws for a nonrelativistic spherical body. We show that it can lead to a deviation from standard gravity inside matter, parametrized by three coefficients which satisfy a consistency relation and can be constrained by present and future astrophysical observations.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/2e0d39112db6793e563d93f864fb01c405b47794

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In Astronomy and Astrophysics

Citations in the corpus

Dark Energy in Light of Multi-Messenger Gravitational-Wave Astronomy (2018, background): “Now, the multi-messenger observation of GW170817 allow us to test if GWs and EM radiation feel the same gravitational potential.”
Horndeski theory and beyond: a review (2019, background): “Even if one imposes cGW = 1, there still is an interesting class of scalar-tensor theories, in which the nonstandard behavior of gravity arises only inside matter [254, 255, 256, 171].”
A systematic approach to generalisations of General Relativity and their cosmological implications (2018, background): “If we decide to be too conservative and ignore the presence of the higher order operators, that would enter naturally from the effective field theory point of view, we can then put very restrictive bounds on the modified gravity theories [275, 276, 277, 278, 279, 280, 281, 282].”
Stellar structure models in modified theories of gravity: Lessons and challenges (2019, background): “[271], that some families of models extending the Horndeski class, like degenerate higher-order scalar-tensor theories (DHOST) may overcome these constraints.”
Dark energy and modified gravity in degenerate higher-order scalar–tensor (DHOST) theories: A review (2018, methodology): “This finally gives the modified gravitational laws [45] (see also [88]) dΦ dr = GNM(r) r2 + Ξ1GNM(r) , dΨ dr = GNM(r) r2 + Ξ2 GNM(r) r + Ξ3GNM(r) , (6.”
Effective field theory of dark energy: A review (2019, background): “(91) is further modified with the inclusion of an additional constant Υ3 if theories such as DHOST are considered [310, 311, 312].”
Gravitational wave decay into dark energy (2018, background): “This implies that the screening mechanism based on quartic terms studied in [47, 48, 31] is absent.”