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arXiv · 1910.09557

Gravitational waves and higher dimensions: Love numbers and Kaluza-Klein excitations

Vitor Cardoso·Leonardo Gualtieri·Christopher J. Moore
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Abstract

Gravitational-wave (GW) observations provide a wealth of information on the nature and properties of black holes. Among these, tidal Love numbers or the multipole moments of the inspiralling and final objects are key to a number of constraints. Here, we consider these observations in the context of higher-dimensional scenarios, with flat large extra dimensions. We show that -- as might be anticipated, but not always appreciated in the literature -- physically motivated set-ups are unconstrained by gravitational-wave data. Dynamical processes that do not excite the Kaluza-Klein (KK) modes lead to a signal identical to that in four-dimensional general relativity in vacuum . In addition, any possible excitation of the KK modes is highly suppressed relative to the dominant quadrupolar term; given existing constraints on the extra dimensions and the masses of the objects seen in gravitational-wave observations, KK modes appear at post-Newtonian order $\sim 10^{11}$. Finally, we re-compute the tidal Love numbers of spherical black holes in higher dimensions. We confirm that these are different from zero, but comparing with previous computations we find a different magnitude and sign.

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Vitor Cardoso, Leonardo Gualtieri, Christopher J. Moore. 2019-10-21. Gravitational waves and higher dimensions: Love numbers and Kaluza-Klein excitations. https://doi.org/10.1103/physrevd.100.124037

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