Speaker
Description
Einstein-Aether theory extends general relativity by introducing a dynamical timelike vector field that breaks Lorentz symmetry/invariance, motivated by quantum gravity approaches including loop quantum gravity models. While maintaining self-consistency and passing all observational constraints, the theory permits superluminal gravitons that revolutionize black hole causal structure, namely, the universal horizon replaces the traditional event horizon as the true causal boundary, trapping particles of arbitrarily large speeds from within. This novel phenomenon modifies gravitational waves at the ringdown stage through altered boundary conditions and the resultant quasi-normal mode spectra, with latter being potentially detectable by future space-based observatories (LISA, TianQin, Taiji, etc.). In addition to phenomenological significance, the universal horizon thus serves as a distinctive fingerprint of Lorentz violation (and a probe to the structure of a black hole). Overcoming formidable technical challenges through reduced Lagrangian methods, this framework opens a theoretical laboratory for probing spacetime causal structure and revealing the nature of gravitational Lorentz-violation effects. Together with different aspects reflected from the gravitational waves at the inspiral stage, we shall build up a more comprehensive as well as systematic understanding towards the theory, serving for uncovering the dawn of quantum gravity plus an illustration of an effective treatment of tackling this sort of problems.
| Research Area | Gravitational waves: black holes |
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