4 research outputs found
Impact of high-order tidal terms on binary neutron-star waveforms
GW170817, the milestone gravitational-wave event originated from a binary
neutron star merger, has allowed scientific community to place a constraint on
the equation of state of neutron stars by extracting the leading-order,
tidal-deformability term from the gravitational waveform. Here we incorporate
tidal corrections to the gravitational-wave phase at next-to-leading and
next-to-next-to-leading order, including the magnetic tidal Love numbers, tail
effects, and the spin-tidal couplings recently computed in Tiziano Abdelsalhin
[Phys. Rev. D 98, 104046 (2018)]. These effects have not yet been included in
the waveform approximants for the analysis of GW170817. We provide a
qualitative and quantitative analysis of the impact of these new terms by
studying the parameter bias induced on events compatible with GW170817 assuming
second-generation (advanced LIGO) and third-generation (Einstein Telescope)
ground-based gravitational-wave interferometers. We find that including the
tidal-tail term deteriorates the convergence properties of the post-Newtonian
expansion in the relevant frequency range. We also find that the effect of
magnetic tidal Love numbers could be measurable for an optimal GW170817 event
with signal-to-noise ratio detected with the Einstein
Telescope. On the same line, spin-tidal couplings may be relevant if mildly
high-spin neutron star binaries exist in nature.Comment: Published version: More optimistic conclusion about detectability due
to higher projected SN
Quasi-normal modes and their overtones at the common horizon in a binary black hole merger
It is expected that all astrophysical black holes in equilibrium are well
described by the Kerr solution. Moreover, any black hole far away from
equilibrium, such as one initially formed in a compact binary merger or by the
collapse of a massive star, will eventually reach a final equilibrium Kerr
state. At sufficiently late times in this process of reaching equilibrium, we
expect that the black hole is modeled as a perturbation around the final state.
The emitted gravitational waves will then be damped sinusoids with frequencies
and damping times given by the quasi-normal mode spectrum of the final Kerr
black hole. An observational test of this scenario, often referred to as black
hole spectroscopy, is one of the major goals of gravitational wave astronomy.
It was recently suggested that the quasi-normal mode description including the
higher overtones might hold even right after the remnant black hole is first
formed. At these times, the black hole is expected to be highly dynamical and
non-linear effects are likely to be important. In this paper we investigate
this remarkable scenario in terms of the horizon dynamics. Working with high
accuracy simulations of a simple configuration, namely the head-on collision of
two non-spinning black holes with unequal masses, we study the dynamics of the
final common horizon in terms of its shear and its multipole moments. We show
that they are indeed well described by a superposition of ringdown modes as
long as a sufficiently large number of higher overtones are included. This
description holds even for the highly dynamical final black hole shortly after
its formation. We discuss the implications and caveats of this result for black
hole spectroscopy and for our understanding of the approach to equilibrium.Comment: 26p., 21 figures, 1 table. To be submitted. Comments welcom
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'