Scalar-tensor theories and modified gravity in the wake of GW170817
Scalar-tensor theories and modified gravity in the wake of GW170817
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DOI：
10.1103/physrevd.97.061501
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发表时间：
2017-11
影响因子：
5
通讯作者：
D. Langlois;R. Saito;Daisuke Yamauchi;K. Noui
中科院分区：
文献类型：
--
作者：
D. Langlois;R. Saito;Daisuke Yamauchi;K. Noui
暗能量和修正引力理论可以受到天体物理或宇宙学观测的强烈约束，最近对引力波事件GW170817和电磁对应物GRB170817A的观测表明，引力波的速度与光速相同，偏差在{10}^{-15}$。这一观察结果意味着对标量张量理论的严格限制，特别是其作用依赖于标量场的二阶导数的理论。在简并高阶标量张量(DHOST)理论的框架下，我们给出了满足${c}{g}=c$的简并高阶标量张量(DHOST)理论。然后，对于这些理论，我们研究了在小尺度上抑制标量相互作用的屏蔽机制，即Vainshtein机制，并计算了非相对论球体的相应引力定律。我们表明，它可以导致物质内部标准重力的偏差，由满足一致性关系的三个系数参数表示，并可以受到现在和未来的天体物理观测的约束。
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.