分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: The energy of gravitational waves is a fundamental problem in gravity theory. The existing descriptions for the energy of gravitational waves, such as the well-known Isaacson energy-momentum tensor, suffer from several defects. Due to the equivalence principle, the gravitational energy-momentum can only be defined quasilocally, being associated with a closed spacelike 2-surface bounding a region. We propose a new approach to derive the energy of gravitational waves $directly$ from the quasilocal gravitational energy. Such an approach is natural and consistent with the quasilocality of gravitational energy-momentum.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: The energy spectrum of gravitational waves (GWs), which depicts the energy of GWs per unit volume of space per logarithmic frequency interval normalized to the critical density of the Universe, is a widely used way for quantifying the sensitivity of GW detectors and the strength of GWs, since it has the advantage of having a clear physical meaning. It was found that the energy spectrum of GWs depends on the gauge when the GWs beyond the linear order perturbations are considered. We show that this gauge dependence issue originates from the inappropriate description for the energy of GWs. With the proper description for the energy of GWs, we give a well-defined energy spectrum of GWs, in which the gauge issue disappears naturally.