Speaker: Fabrizio Corelli (Sapienza University of Rome)
Title: Nonlinear echoes from black holes in Einstein-Maxwell-scalar theory
Abstract: The post-merger portion of the gravitational wave emitted in a binary coalescence encodes precious information about the structure of the remnant. While in the case of a black hole in General Relativity the signal is described by a standard ringdown, when considering different objects, or alternative theories of gravity, new features might emerge. In this context an interesting possibility is the appearance of echoes. While they are generally studied for exotic compact objects, it has recently been found that they might arise also for black holes in the Einstein-Maxwell-scalar extension to General Relativity. Indeed, in a particular region of the parameter space, this theory admits hairy black hole configurations whose effective potential under scalar or gravitational perturbations features cavity-like structures, where radiation can be trapped and echoes can be generated. In a recent work, carried out in collaboration with Marco Melis, Robin Croft and Paolo Pani, we computed the quasi-normal frequencies of such black hole solutions, for radial and axial modes. Furthermore, by performing simulations of the spherical collapse of scalar wave packets, we have been able to observe the presence of echo patterns in the time-domain behavior of the scalar field, even in the regime where nonlinearities are significant. In this talk I will present the results of our study and discuss our follow-up project, in which we will simulate the head-on collision process with the aim of investigating whether echoes are preserved in such a scenario, or they are quenched by other dynamical effects.
Reference: Melis, Corelli, Croft and Pani, Phys. Rev. D 111, 064072 (2025), arXiv:2412.14259 [gr-qc].
Room: Sala de Reuniões e Seminários (2-8.3, 2nd Floor of Physics Building)