5 research outputs found
From black holes to their progenitors: A full population study in measuring black hole binary parameters from ringdown signals
A perturbed black hole emits gravitational radiation, usually termed the
ringdown signal, whose frequency and time-constant depends on the mass and spin
of the black hole. I investigate the case of a binary black hole merger
resulting from two initially non-spinning black holes of various mass ratios,
in quasi-circular orbits. The observed ringdown signal will be determined,
among other things, by the black hole's spin-axis orientation with respect to
Earth, its sky position and polarization angle - parameters which can take any
values in a particular observation. I have carried out a statistical analysis
of the effect of these variables, focusing on detection and measurement of the
multimode ringdown signals using the reformulated European LISA mission, Next
Gravitational-Wave Observatory, NGO, the third generation ground-based
observatory, Einstein Telescope and the advanced era detector, aLIGO. To the
extent possible I have discussed the effect of these results on plausible event
rates, as well as astrophysical implications concerning the formation and
growth of supermassive and intermediate mass black holes.Comment: 12 pages, 9 figures, accepted for publication in Amaldi 9 & NRDA
Proceedings, Journal of Physics: Conference Serie
Is black-hole ringdown a memory of its progenitor?
We have performed an extensive numerical study of coalescing black-hole
binaries to understand the gravitational-wave spectrum of quasi-normal modes
excited in the merged black hole. Remarkably, we find that the masses and spins
of the progenitor are clearly encoded in the mode spectrum of the ringdown
signal. Some of the mode amplitudes carry the signature of the binary's mass
ratio, while others depend critically on the spins. Simulations of precessing
binaries suggest that our results carry over to generic systems. Using Bayesian
inference, we demonstrate that it is possible to accurately measure the mass
ratio and a proper combination of spins even when the binary is itself
invisible to a detector. Using a mapping of the binary masses and spins to the
final black hole spin, allows us to further extract the spin components of the
progenitor. Our results could have tremendous implications for gravitational
astronomy by facilitating novel tests of general relativity using merging black
holes.Comment: 5 pages, 3 figures, 1 table, accepted for publication in Physical
Review Letter
Gravitational-wave radiation from merging binary black holes and Supernovae
This thesis is conceptually divided into two parts. The first and main part concerns
the generation of gravitational radiation that is emitted from merging black-hole
binary systems using Numerical Relativity methods. The second part presents
the methodology of the search for gravitational-wave bursts that are emitted in
core-collapse Supernovae.
My approach to Numerical Relativity is to utilise the late-time gravitational
radiation of merging binary black holes to extract key astrophysical parameters
from such systems via standard parameter estimation techniques. I begin with
an introductory chapter that outlines the standard theories of stationary and
perturbed black holes. In addition, up-to-date techniques in performing binary
black hole simulations, the current and near-future status of the global network
of gravitational-wave detectors, as well as the most promising gravitational-wave
sources. I conclude the chapter with elements on parameter estimation techniques,
such as Bayesian analysis and the Fisher information matrix. In Chapter 2, I discuss
detection issues and parameter estimation results from the late-time radiation
of colliding non-spinning black holes in quasi-circular orbits, and propose a practical
test of General Relativity, as well as of the nature of the merged compact
object. Chapter 3 involves similar parameter extraction calculations, but involves
a more realistic approach, whereby the effect of the various angular parameters
on parameter estimation is considered, placing an emphasis on the actual science
benefit from measuring the gravitational radiation from perturbed intermediate
and supermassive black holes. In Chapter 4 we present the results of an extensive
Numerical Relativity study of merging spinning black hole binaries and argue that
the mass ratio and individual spins of a non-precessing progenitor binary can be
measured solely by observing the late-time radiation.
Chapter 5 presents the methodology in carrying out searches for gravitationalwave
bursts (GWB) from core-collapse Supernovae with a dedicated for GWB
searches pipeline (X-Pipeline) and presents the sensitivity performance of XPipeline
in detecting GWBs associated with certain Supernova candidates during
the two most recent LIGO-Virgo-GEO Science Runs
Black-hole hair loss: learning about binary progenitors from ringdown signals
Perturbed Kerr black holes emit gravitational radiation, which (for the
practical purposes of gravitational-wave astronomy) consists of a superposition
of damped sinusoids termed quasi-normal modes. The frequencies and
time-constants of the modes depend only on the mass and spin of the black hole
- a consequence of the no-hair theorem. It has been proposed that a measurement
of two or more quasi-normal modes could be used to confirm that the source is a
black hole and to test if general relativity continues to hold in ultra-strong
gravitational fields. In this paper we propose a practical approach to testing
general relativity with quasi-normal modes. We will also argue that the
relative amplitudes of the various quasi-normal modes encode important
information about the origin of the perturbation that caused them. This helps
in inferring the nature of the perturbation from an observation of the emitted
quasi-normal modes. In particular, we will show that the relative amplitudes of
the different quasi-normal modes emitted in the process of the merger of a pair
of nonspinning black holes can be used to measure the component masses of the
progenitor binary.Comment: 24 pages, 9 figures, 4 tables, accepted for publication in Physical
Review