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20/12/2022, 14:30
It is broadly believed that quasinormal modes (QNMs) cannot tell the black-hole near-horizon geometry, because usually the low-lying modes are determined by the scattering of perturbations around the peak of the effective potential. Using the general parametrization of the black-hole spacetimes respecting the generic post-Newtonian asymptotic, we will show that tiny modifications of the...
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20/12/2022, 14:45
It was recently shown that small perturbations due, e.g., to environmental effects (the “flea”) to the effective potential governing gravitational-wave generation and propagation in black hole exteriors (the “elephant”) can lead to arbitrarily large changes in the black hole’s quasinormal spectrum. This raises an important question: is the black hole spectroscopy program robust against...
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20/12/2022, 15:00
Ringdown offers a unique possibility to study the spacetime in extreme curvature regimes, to test general relativity and better understand the nature of black holes. The ringdown corresponds to the last phase of black hole binary coalescences, when the newly formed black hole relaxes to its stationary Kerr state by emitting gravitational waves. The linear theory of black hole perturbations...
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20/12/2022, 15:15
Recent investigations of the pseudospectrum in black hole spacetimes have shown that quasinormal mode frequencies suffer from spectral instabilities. We extend the pseudospectrum analysis to horizon- less exotic compact objects which possess a reflective surface arbitrarily close to the Schwarzschild radius, and find that their quasinormal modes also suffer from an overall spectral...
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20/12/2022, 15:30
The coupling between the angular momentum of a compact object and an external tidal field gives rise to the “rotational” tidal Love numbers, which affect the tidal deformability of a spinning self-gravitating body and enter the gravitational waveform of a binary inspiral at high post-Newtonian order. In this talk I will present an unexpected symmetry of these quantities in slowly-rotating...
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20/12/2022, 15:45
The tidal response of a compact object is a key gravitational-wave observable encoding information about its interior. This link is subtle due to the nonlinearities of general relativity. We show that considering a scattering process bypasses challenges with potential ambiguities, as the tidal response is determined by the asymptotic in- and outgoing waves at null infinity. As an application...
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