16 research outputs found
Modeling and detecting resonant tides of exotic compact objects
The event horizon of a black hole in general relativity absorbs all infalling
radiation. Any observation of the contrary would immediately challenge the
expectation that astrophysical black holes are described by the vacuum Kerr
geometry. If a putative black hole does reflect part of the ingoing radiation,
its quasinormal mode structure is drastically altered. Low frequency modes can
be introduced that are resonantly excited during the inspiral of a binary
system. We study the resulting phase shift of the gravitational wave signal.
Building on neutron star results, we obtain a model-independent expression for
the phase shift that depends only on quasinormal modes and Love numbers of the
compact object. We find that the phase shift might be detectable with Einstein
Telescope for asymmetric binaries in high signal-to-noise events (),
but by far cannot explore the Planck scale.Comment: 23 pages, 3 figures. Fixed error, modified detection prospect
Gravitational waves from plunges into Gargantua
We analytically compute time domain gravitational waveforms produced in the
final stages of extreme mass ratio inspirals of non-spinning compact objects
into supermassive nearly extremal Kerr black holes. Conformal symmetry relates
all corotating equatorial orbits in the geodesic approximation to circular
orbits through complex conformal transformations. We use this to obtain the
time domain Teukolsky perturbations for generic equatorial corotating plunges
in closed form. The resulting gravitational waveforms consist of an
intermediate polynomial ringdown phase in which the decay rate depends on the
impact parameters, followed by an exponential quasi-normal mode decay. The
waveform amplitude exhibits critical behavior when the orbital angular momentum
tends to a minimal value determined by the innermost stable circular orbit. We
show that either near-critical or large angular momentum leads to a significant
extension of the LISA observable volume of gravitational wave sources of this
kind.Comment: 80 pages, 28 figures, corrigendum versio
Quasinormal modes of rotating black holes in higher-derivative gravity
We compute the spectrum of linearized gravitational excitations of black
holes with substantial angular momentum in the presence of higher-derivative
corrections to general relativity. We do so perturbatively to leading order in
the higher-derivative couplings and up to order fourteen in the black hole
angular momentum. This allows us to accurately predict quasinormal mode
frequencies of black holes with spins up to about of the extremal value.
For some higher-derivative corrections, we find that sizable rotation enhances
the frequency shifts by almost an order of magnitude relative to the static
case.Comment: 5 pages+appendices, 2 figure
The universal Teukolsky equations and black hole perturbations in higher-derivative gravity
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 universal Teukolsky equations. We
detail a complete computational strategy to obtain these decoupled equations in
general higher-derivative theories. We apply this to six-derivative gravity to
compute the shifts in the quasinormal mode frequencies with respect to those of
Kerr black holes in general relativity. At linear order in the angular momentum
we reproduce earlier results obtained with a metric perturbation approach. In
contrast with this earlier work, however, the method given here applies also to
post-merger black holes with significant spin, which are of particular
observational interest.Comment: 50 pages, 5 figures. v2: we fixed an error in our code and this led
to improved results for the QNMs reported in section 6. The rest of the
sections remain unchanged up to small adjustements. Conclusions unchanged.
Version sent to the journal. We provide an ancillary Mathematica notebook
with the modified Teukolsky radial equations for the (l,m)=(2,3) and (3,3)
modes in six-derivative gravit
Black holes, gravitational waves and fundamental physics: a roadmap
The grand challenges of contemporary fundamental physics—dark matter, dark energy, vacuum energy, inflation and early universe cosmology, singularities and the hierarchy problem—all involve gravity as a key component. And of all gravitational phenomena, black holes stand out in their elegant simplicity, while harbouring some of the most remarkable predictions of General Relativity: event horizons, singularities and ergoregions.
The hitherto invisible landscape of the gravitational Universe is being unveiled before our eyes: the historical direct detection of gravitational waves by the LIGO-Virgo collaboration marks the dawn of a new era of scientific exploration. Gravitational-wave astronomy will allow us to test models of black hole formation, growth and evolution, as well as models of gravitational-wave generation and propagation. It will provide evidence for event horizons and ergoregions, test the theory of General Relativity itself, and may reveal the existence of new fundamental fields. The synthesis of these results has the potential to radically reshape our understanding of the cosmos and of the laws of Nature.
The purpose of this work is to present a concise, yet comprehensive overview of the state of the art in the relevant fields of research, summarize important open problems, and lay out a roadmap for future progress. This write-up is an initiative taken within the framework of the European Action on 'Black holes, Gravitational waves and Fundamental Physics'