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arXiv · 2405.01297

Boosting gravitational waves: a review of kinematic effects on amplitude, polarization, frequency and energy density

Giulia Cusin·Cyril Pitrou·Camille Bonvin·Aurélien Barrau·Killian Martineau
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Abstract

We review the kinematic effects on a gravitational wave due to either a peculiar motion of the astrophysical source emitting it or a local motion of the observer. Working in the context of general relativity, we show at fully non-linear order in velocity, that the amplitude of the wave is amplified by the Doppler factor in the case in which the source moves with respect to a reference frame, while it is invariant if the observer moves (with respect to a reference observer). However, the observed specific intensity transforms in the same way under a boost of the source or of the observer. We also show at fully non-linear order that under a boost (of either source or observer), the polarization tensor is rotated in the same way the wave direction is rotated by aberration, such that the only net effect of a boost on polarization is to change the phase of the helicity components. We apply these results to a wave emitted by a binary system of compact objects in the cosmological context.

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Giulia Cusin, Cyril Pitrou, Camille Bonvin, Aurélien Barrau, Killian Martineau. 2024-05-02. Boosting gravitational waves: a review of kinematic effects on amplitude, polarization, frequency and energy density. https://doi.org/10.1088/1361-6382%2Fad7ad0

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