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Spinning Black Holes Fall in Love
Alexandre Le Tiec1,2, Marc Casals2,3
1Laboratoire Univers et Théories, Observatoire de Paris, CNRS, Université PSL, Université de Paris, 92190 Meudon, France.
Physical Review Letters
|April 16, 2021
Summary
Black holes are surprisingly rigid and resist tidal deformation. This study proves Love tensors vanish for non-spinning black holes but are nonzero for spinning ones, impacting astrophysics and gravitational-wave astronomy.
Area of Science:
- Fundamental physics
- Astrophysics
- Gravitational-wave astronomy
Background:
- Tidal deformability of compact objects like Kerr black holes is crucial for understanding their interaction with external gravitational fields.
- Love tensors quantify this tidal deformability.
Purpose of the Study:
- To investigate whether black holes can be tidally deformed by external gravitational fields.
- To determine the conditions under which Love tensors for Kerr black holes are non-zero.
Main Methods:
- Proving the vanishing of Love tensors for Kerr black holes in the nonspinning limit or under axisymmetric tidal perturbation.
- Calculating closed-form Love tensors for spinning black holes to linear order in spin and tidal field strength.
Main Results:
- Love tensors identically vanish for non-spinning Kerr black holes and under axisymmetric tidal perturbations.
- Love tensors are generically non-zero for spinning Kerr black holes.
- For a dimensionless spin of ~0.1, quadrupolar Love tensors are approximately 2x10^-3, indicating significant rigidity.
Conclusions:
- Black holes exhibit considerable rigidity against tidal deformation, especially when not spinning.
- The non-zero Love tensors for spinning black holes have implications for gravitational-wave astronomy and fundamental physics.
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