2025/09/17 by Lai, Xiao-Bin, Dong, Yu-Qi, Fan, Yu-Zhi +1 · 5 citations
#FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc)
paper · doi:10.48550/arxiv.2509.13958
We constrain the parameter space of the Bumblebee model within a cosmological background and investigate the properties of gravitational waves under the constrained parameter space. Specifically, we derive the conditions for the absence of ghost instability, Laplacian instability, and tachyonic instability for perturbations in a cosmological background. By incorporating the observed accelerated expansion of the universe and the observational constraints on tensor gravitational waves, we derive bounds on the parameter space of the Bumblebee model. We then examine the polarization modes, the propagation speeds, and the amplitude relations of gravitational waves within this constrained framework. Our results indicate that the non-minimal coupling parameter ξ must be non-positive, and the Lorentz-violating parameter ξb2 has a lower bound on the order of 10-15. The propagation modes of gravitational waves in the Bumblebee model consist of two tensor modes, two vector modes, and a combination of two scalar modes. Notably, the tensor modes travel at subluminal speeds, whereas the vector and scalar modes propagate at superluminal speeds. These results provide a concrete theoretical framework and specific observational signatures for testing Lorentz invariance in the gravitational sector with future gravitational-wave detectors.