We reduce the study of perturbations of rotating black holes in higher-derivative extensions
of general relativity to a system of decoupled radial equations that stem from a set of …

We study extreme mass-ratio binary systems in which a stellar mass compact object spirals
into a supermassive black hole surrounded by a scalar cloud. Scalar clouds can form …

The purpose of this chapter is to provide an overview of the exciting field of black hole quasi-
normal modes and its capabilities to test general relativity in the 21st century. After …

In this work, by a novel approach to studying the scattering of a Schwarzschild black hole,
the non-commutativity is introduced as perturbation. We begin by reformulating the Klein …

We often encounter a situation where linear wave equations around a black hole solution
can be regarded as continuous deformations of simpler ones, or modifications from the …

Black hole spectroscopy is a clean and powerful tool to test gravity in the strong-field regime
and to probe the nature of compact objects. Next-generation ground-based detectors, such …

LISA, the Laser Interferometer Space Antenna, will usher in a new era in gravitational-wave
astronomy. As the first anticipated space-based gravitational-wave detector, it will expand …

Black-hole spectroscopy is a powerful tool to probe the Kerr nature of astrophysical compact
objects and their environment. The observation of multiple ringdown modes in gravitational …

We report a new method to calculate the quasinormal modes of rotating black holes, using a
spectral decomposition to solve the partial differential equations that result from introducing …

The ringdown phase of gravitational waves emitted by a perturbed black hole is described
by a superposition of exponentially decaying sinusoidal modes, called quasinormal modes …