3 papers
gr-qc2023
Scalar Gravitational Waves Can Be Generated Even Without Direct Coupling Between Dark Energy and Ordinary Matter
Li-Ying Chou, Yi-Zen Chu, Yen-Wei Liu
We point out, the scalar sector of gravitational perturbations may be excited by an isolated astrophysical system immersed in a universe whose accelerated expansion is not due to t…
gr-qc2021
Late time tails and nonlinear memories in asymptotically de Sitter spacetimes
Yi-Zen Chu, M. Afif Ismail, Yen-Wei Liu
We study the propagation of a massless scalar wave in de Sitter spacetime perturbed by an arbitrary central mass. By focusing on the late time limit, this probes the portion of the…
gr-qc2019
The Transverse-Traceless Spin-2 Gravitational Wave Cannot Be A Standalone Observable Because It Is Acausal
Yi-Zen Chu, Yen-Wei Liu
We show, through an explicit calculation of the relevant Green's functions, that the transverse-traceless (TT) portion of the gravitational perturbations of Minkowski spacetime and…