Wolf William J, Lagos Macarena
Kavli Institute for Cosmological Physics, The University of Chicago, Chicago, Illinois 60637, USA.
Phys Rev Lett. 2020 Feb 14;124(6):061101. doi: 10.1103/PhysRevLett.124.061101.
Cosmological models with a dynamical dark energy field typically lead to a modified propagation of gravitational waves via an effectively time-varying gravitational coupling G(t). The local variation of this coupling between the time of emission and detection can be probed with standard sirens. Here we discuss the role that lunar laser ranging (LLR) and binary pulsar constraints play in the prospects of constraining G(t) with standard sirens. In particular, we argue that LLR constrains the matter-matter gravitational coupling G_{N}(t), whereas binary pulsars and standard sirens constrain the quadratic kinetic gravity self-interaction G_{gw}(t). Generically, these two couplings could be different in alternative cosmological models, in which case LLR constraints are irrelevant for standard sirens. We use the Hulse-Taylor pulsar data and show that observations are highly insensitive to time variations of G_{gw}(t) yet highly sensitive to G_{N}(t). We thus conclude that future gravitational waves data will become the best probe to test G_{gw}(t), and will hence provide novel constraints on dynamical dark energy models.
具有动态暗能量场的宇宙学模型通常会通过有效时变的引力耦合G(t)导致引力波传播的修正。这种耦合在发射和探测时刻之间的局部变化可以用标准引力波源来探测。在这里，我们讨论月球激光测距（LLR）和双脉冲星约束在利用标准引力波源约束G(t)的前景中所起的作用。特别是，我们认为LLR约束物质-物质引力耦合G_N(t)，而双脉冲星和标准引力波源约束二次动能引力自相互作用G_gw(t)。一般来说，在替代宇宙学模型中，这两种耦合可能不同，在这种情况下，LLR约束与标准引力波源无关。我们使用了赫尔斯-泰勒脉冲星数据，并表明观测对G_gw(t)的时间变化高度不敏感，但对G_N(t)高度敏感。因此，我们得出结论，未来的引力波数据将成为测试G_gw(t)的最佳探针，从而为动态暗能量模型提供新的约束。
