BH4 - Gravitational fields with sources: From compact objects to black holes |
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Speaker |
Pani, Paolo |
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Coauthors |
Paolo Pani, Leonardo Gualtieri, Andrea Maselli, Valeria Ferrari |
| Talk Title |
Tidal deformations of a spinning compact object |
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Abstract |
The deformability of a compact object induced by a perturbing tidal field is encoded in the tidal Love numbers, which depend sensibly on the object's internal structure. Tidal Love numbers are known only for static, spherically-symmetric objects. We present powerful perturbative techniques to compute the geometry of a tidally-distorted spinning object to second order in the angular momentum. The spin of the object introduces couplings between electric and magnetic deformations and new classes of induced Love numbers emerge. For example, a spinning object immersed in a quadrupolar, electric tidal field can acquire some induced mass, spin, quadrupole, octupole and hexadecapole moments to second order in the spin. The deformations are encoded in a set of inhomogeneous differential equations which, remarkably, can be solved analytically in vacuum. We prove that the tidal Love numbers of a Kerr black hole are zero to second order in the spin and provide the explicit solution for a slowly-rotating, tidally-deformed Kerr black hole. Finally, we discuss the tidal Love numbers of a slowly-spinning neutron star. |
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