Applications of the close-limit approximation: horizonless compact objects and scalar fields

Abstract

The ability to model the evolution of compact binaries from the inspiral to coalescence is central to gravitational wave astronomy. Current waveform catalogues are built from vacuum binary black hole models, by evolving Einstein equations numerically and complementing them with knowledge from slow-motion expansions. Much less is known about the coalescence process in the presence of matter, or in theories other than General Relativity. Here, we explore the Close Limit Approximation as a powerful tool to understand the coalescence process in general setups. In particular, we study the head-on collision of two equal-mass, compact but horizonless objects. Our results show the appearance of ``echoes'' and indicate that a significant fraction of the merger energy goes into these late-time repetitions. We also apply the Close Limit Approximation to investigate the effect of colliding black holes on surrounding scalar fields. Notably, our results indicate that observables obtained through perturbation theory may be extended to a significant segment of the merger phase, where in principle only a numerical approach is appropriate.

16 pages, 4 figures. Matches published version in CQG

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Cited by in corpus (6)

• The Science of the Einstein Telescope
• Nonlinear treatment of a black hole mimicker ringdown
• Echoes from backreacting exotic compact objects
• Whispers from the quantum core: the ringdown of semiclassical stars
• Splitting the Echoes of Black Holes in Einstein-nonlinear Electrodynamic Theories
• Is GW190521 a gravitational wave echo of wormhole remnant from another universe?