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arXiv · 2309.11024

On spin optics for gravitational waves lensed by a rotating object

Kei-ichiro Kubota·Shun Arai·Shinji Mukohyama
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Abstract

We study gravitational lensing of gravitational waves taking into account the spin of a graviton coupled with a dragged spacetime made by a rotating object. We decompose the phase of gravitational waves into helicity-dependent and independent components with spin optics, analyzing waves whose wavelengths are shorter than the curvature radius of a lens object. We analytically confirm that the trajectory of gravitational waves splits depending on the helicity, generating additional time delay and elliptical polarization onto the helicity-independent part. We exemplify monotonic gravitational waves lensed by a Kerr black hole and derive the analytical expressions of corrections in phase and magnification. The corrections are enhanced for longer wavelengths, potentially providing a novel probe of rotational properties of lens objects in low-frequency gravitational-wave observations in the future.

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Kei-ichiro Kubota, Shun Arai, Shinji Mukohyama. 2023-09-20. On spin optics for gravitational waves lensed by a rotating object. https://doi.org/10.1103/physrevd.109.044027

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