Ricerc@Sapienza

A new breakthrough in gravitational wave physics is behind the corner: with design sensitivities interferometers and next generation detectors, previously unreached areas of the Universe will be explored with unmatched precision in the next years. An equally important step forward is expected from the theoretical side, as new opportunities to test Einstein's theory of gravity will be available.
The late-time signal, called ringdown, emitted by the coalescence of two compact objects carries all the fundamental features of the ultimate description of gravity, so far partially concealed due to experimental limitations in the signal-to-noise ratio. In the ringdown phase, the remnant of the binary system is a highly perturbed black hole that relaxes to equilibrium through peculiar oscillations, called quasinormal modes (QNMs). If these modes are found to be dependent on other parameters besides the mass and the spin of the black hole, it will be a clear sign of General Relativity (GR) breaking down. With the imminent technological advancement, it will be possible to verify this possibility and assess the nature of GR deviations comparing ringdown observations with theoretical predictions in modified theories of gravity.
As the ringdown signal is observed with more and more accuracy, is of utmost importance to find the QNMs emitted by black holes in alternative theories of gravity. With this project I plan to lead the way towards this goal, considering a specific theory as a case study: Einstein-dilaton Gauss-Bonnet (EdGB), which is arguably the simplest theory modifying GR in the large curvature regime. I will develop a method to compute the QNMs of slowly rotating EdGB Black Holes and I will show how to use these results as direct tests of GR with current and future observations. Finally, I will generalize this framework to easily adapt it to other theories, in order to provide a first catalogue of quasinormal mode spectra in modified theories of gravity.