243 research outputs found
Small mass plunging into a Kerr black hole: Anatomy of the inspiral-merger-ringdown waveforms
We numerically solve the Teukolsky equation in the time domain to obtain the
gravitational-wave emission of a small mass inspiraling and plunging into the
equatorial plane of a Kerr black hole. We account for the dissipation of
orbital energy using the Teukolsky frequency-domain gravitational-wave fluxes
for circular, equatorial orbits, down to the light-ring. We consider Kerr spins
, and compute the inspiral-merger-ringdown (2,2),
(2,1), (3,3), (3,2), (4,4), and (5,5) modes. We study the large-spin regime,
and find a great simplicity in the merger waveforms, thanks to the extremely
circular character of the plunging orbits. We also quantitatively examine the
mixing of quasinormal modes during the ringdown, which induces complicated
amplitude and frequency modulations in the waveforms. Finally, we explain how
the study of small mass-ratio black-hole binaries helps extending
effective-one-body models for comparable-mass, spinning black-hole binaries to
any mass ratio and spin magnitude.Comment: 20 pages, 15 figure
Modeling gravitational waves from compact-object binaries
The direct observation and characterization of gravitational waves from binary black-hole mergers by LIGO is a testament to the crucial role played by waveform modeling in these discoveries. I will review recent developments in the ïŹeld, discussing both numerical and analytical approaches to the problem of black-hole binaries and their gravitational-wave emission
Numerical relativity reaching into post-Newtonian territory: a compact-object binary simulation spanning 350 gravitational-wave cycles
We present the first numerical-relativity simulation of a compact-object
binary whose gravitational waveform is long enough to cover the entire
frequency band of advanced gravitational-wave detectors, such as LIGO, Virgo
and KAGRA, for mass ratio 7 and total mass as low as . We find
that effective-one-body models, either uncalibrated or calibrated against
substantially shorter numerical-relativity waveforms at smaller mass ratios,
reproduce our new waveform remarkably well, with a negligible loss in detection
rate due to modeling error. In contrast, post-Newtonian inspiral waveforms and
existing calibrated phenomenological inspiral-merger-ringdown waveforms display
greater disagreement with our new simulation. The disagreement varies
substantially depending on the specific post-Newtonian approximant used
Inspiral-merger-ringdown waveforms of spinning, precessing black-hole binaries in the effective-one-body formalism
We describe a general procedure to generate spinning, precessing waveforms
that include inspiral, merger and ringdown stages in the effective-one-body
(EOB) approach. The procedure uses a precessing frame in which
precession-induced amplitude and phase modulations are minimized, and an
inertial frame, aligned with the spin of the final black hole, in which we
carry out the matching of the inspiral-plunge to merger-ringdown waveforms. As
a first application, we build spinning, precessing EOB waveforms for the
gravitational modes l=2 such that in the nonprecessing limit those waveforms
agree with the EOB waveforms recently calibrated to numerical-relativity
waveforms. Without recalibrating the EOB model, we then compare EOB and
post-Newtonian precessing waveforms to two numerical-relativity waveforms
produced by the Caltech-Cornell-CITA collaboration. The numerical waveforms are
strongly precessing and have 35 and 65 gravitational-wave cycles. We find a
remarkable agreement between EOB and numerical-relativity precessing waveforms
and spins' evolutions. The phase difference is ~ 0.2 rad at merger, while the
mismatches, computed using the advanced-LIGO noise spectral density, are below
2% when maximizing only on the time and phase at coalescence and on the
polarization angle.Comment: 17 pages, 10 figure
Prototype effective-one-body model for nonprecessing spinning inspiral-merger-ringdown waveforms
We first use five non-spinning and two mildly spinning (chi_i \simeq -0.44,
+0.44) numerical-relativity waveforms of black-hole binaries and calibrate an
effective-one-body (EOB) model for non-precessing spinning binaries, notably
its dynamics and the dominant (2,2) gravitational-wave mode. Then, we combine
the above results with recent outcomes of small-mass-ratio simulations produced
by the Teukolsky equation and build a prototype EOB model for detection
purposes, which is capable of generating inspiral-merger-ringdown waveforms for
non-precessing spinning black-hole binaries with any mass ratio and individual
black-hole spins -1 \leq chi_i \lesssim 0.7. We compare the prototype EOB model
to two equal-mass highly spinning numerical-relativity waveforms of black holes
with spins chi_i = -0.95, +0.97, which were not available at the time the EOB
model was calibrated. In the case of Advanced LIGO we find that the mismatch
between prototype-EOB and numerical-relativity waveforms is always smaller than
0.003 for total mass 20-200 M_\odot, the mismatch being computed by maximizing
only over the initial phase and time. To successfully generate merger waveforms
for individual black-hole spins chi_i \gtrsim 0.7, the prototype-EOB model
needs to be improved by (i) better modeling the plunge dynamics and (ii)
including higher-order PN spin terms in the gravitational-wave modes and
radiation-reaction force.Comment: 20 pages, 8 figures. Minor changes to match version accepted for
publication in PR
Approaching the Post-Newtonian Regime with Numerical Relativity: A Compact-Object Binary Simulation Spanning 350 Gravitational-Wave Cycles
We present the first numerical-relativity simulation of a compact-object binary whose gravitational waveform is long enough to cover the entire frequency band of advanced gravitational-wave detectors, such as LIGO, Virgo, and KAGRA, for mass ratio 7 and total mass as low as 45.5M_â. We find that effective-one-body models, either uncalibrated or calibrated against substantially shorter numerical-relativity waveforms at smaller mass ratios, reproduce our new waveform remarkably well, with a negligible loss in detection rate due to modeling error. In contrast, post-Newtonian inspiral waveforms and existing calibrated phenomenological inspiral-merger-ringdown waveforms display greater disagreement with our new simulation. The disagreement varies substantially depending on the specific post-Newtonian approximant used
Error-analysis and comparison to analytical models of numerical waveforms produced by the NRAR Collaboration
The Numerical-Relativity-Analytical-Relativity (NRAR) collaboration is a
joint effort between members of the numerical relativity, analytical relativity
and gravitational-wave data analysis communities. The goal of the NRAR
collaboration is to produce numerical-relativity simulations of compact
binaries and use them to develop accurate analytical templates for the
LIGO/Virgo Collaboration to use in detecting gravitational-wave signals and
extracting astrophysical information from them. We describe the results of the
first stage of the NRAR project, which focused on producing an initial set of
numerical waveforms from binary black holes with moderate mass ratios and
spins, as well as one non-spinning binary configuration which has a mass ratio
of 10. All of the numerical waveforms are analysed in a uniform and consistent
manner, with numerical errors evaluated using an analysis code created by
members of the NRAR collaboration. We compare previously-calibrated,
non-precessing analytical waveforms, notably the effective-one-body (EOB) and
phenomenological template families, to the newly-produced numerical waveforms.
We find that when the binary's total mass is ~100-200 solar masses, current EOB
and phenomenological models of spinning, non-precessing binary waveforms have
overlaps above 99% (for advanced LIGO) with all of the non-precessing-binary
numerical waveforms with mass ratios <= 4, when maximizing over binary
parameters. This implies that the loss of event rate due to modelling error is
below 3%. Moreover, the non-spinning EOB waveforms previously calibrated to
five non-spinning waveforms with mass ratio smaller than 6 have overlaps above
99.7% with the numerical waveform with a mass ratio of 10, without even
maximizing on the binary parameters.Comment: 51 pages, 10 figures; published versio
First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data
Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of
continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a
fully coherent search, based on matched filtering, which uses the position and rotational parameters
obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signalto-
noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch
between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have
been developed, allowing a fully coherent search for gravitational waves from known pulsars over a
fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of
11 pulsars using data from Advanced LIGOâs first observing run. Although we have found several initial
outliers, further studies show no significant evidence for the presence of a gravitational wave signal.
Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of
the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for
the first time. For an additional 3 targets, the median upper limit across the search bands is below the
spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried
out so far
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