Sommaire:

In the coalescence of black holes, the ringdown phase consists of the relaxation of the highly perturbed, newly formed black hole to its equilibrium state. Quasi-normal modes (QNM) are associated with the complex frequencies which characterise the dynamics of this relaxation phenomenon (oscillation + damping). Observations of the ringdown could be extremely effective to constrain (or reveal) potential deviations from General Relativity (GR) if the QNM spectrum is found to agree (or disagree) with predictions of GR. This is also an ideal playground to test alternative theories of gravitation. However, in these alternative theories of gravity, not only the problem of computing QNM is generally (much) more involved than in GR but also it is not clear whether one could technically proceed as in GR. For these reasons, with a few exceptions, there has been few results on black holes perturbation theory and QNM in modified theories of gravity. In this seminar, I will present a novel (and potentially powerful) approach we have recently developped in a series of paper to study black holes perturbation theory and to compute QNM in a very large class of theories of modified gravity. I will illustrate the method with physically relevant examples for which the usual techniques are not available and I will present new interesting physical effects concerning QNM in scalar-tensor theories. This new approach paves the way for a systematic treatment of QNM in theories of modified gravity and might be an important step towards a deeper understanding of gravitation in the strong field regime.

Pour plus d'informations, merci de contacter Lavalle J.