Quasinormal modes are eigenmodes of dissipative systems. Perturbations of classical
gravitational backgrounds involving black holes or branes naturally lead to quasinormal …

Perturbations of stars and black holes have been one of the main topics of relativistic
astrophysics for the last few decades. They are of particular importance today, because of …

We analyze GW150914 postmerger data to understand if ringdown overtone detection
claims are robust. We find no evidence in favor of an overtone in the data after the waveform …

In the analysis of a binary black hole coalescence, it is necessary to include gravitational self-
interactions in order to describe the transition of the gravitational wave signal from the …

We present a semianalytic technique for determining the complex normal-mode frequencies
of black holes. The method makes use of the WKB approximation, carried to third order …

We propose two frequency-domain filters to analyze ringdown signals of binary black hole
mergers. The first rational filter is constructed based on a set of (arbitrary) quasinormal …

We describe a new analytic approach to the problem of black-hole oscillations, which has
been investigated numerically thus far. Our treatment is based on a connection between the …

We derive the quadratic action for the physical degrees of freedom of massless spin-0, spin-
1, and spin-2 perturbations on a Schwarzschild-(A) dS background in arbitrary dimensions …

The radiative Green's function for the one-dimensional wave equation with the Regge-
Wheeler and Zerilli potentials is formally constructed from recently developed analytic …

Assuming that general relativity is the correct theory of gravity in the strong-field limit, can
gravitational-wave observations distinguish between black holes and other compact object …