328 research outputs found
Intermediate-mass-ratio-inspirals in the Einstein Telescope. II. Parameter estimation errors
We explore the precision with which the Einstein Telescope (ET) will be able
to measure the parameters of intermediate-mass-ratio inspirals (IMRIs). We
calculate the parameter estimation errors using the Fisher Matrix formalism and
present results of a Monte Carlo simulation of these errors over choices for
the extrinsic parameters of the source. These results are obtained using two
different models for the gravitational waveform which were introduced in paper
I of this series. These two waveform models include the inspiral, merger and
ringdown phases in a consistent way. One of the models, based on the transition
scheme of Ori & Thorne [1], is valid for IMBHs of arbitrary spin, whereas the
second model, based on the Effective One Body (EOB) approach, has been
developed to cross-check our results in the non-spinning limit. In paper I of
this series, we demonstrated the excellent agreement in both phase and
amplitude between these two models for non-spinning black holes, and that their
predictions for signal-to-noise ratios (SNRs) are consistent to within ten
percent. We now use these models to estimate parameter estimation errors for
binary systems with masses 1.4+100, 10+100, 1.4+500 and 10+500 solar masses
(SMs), and various choices for the spin of the central intermediate-mass black
hole (IMBH). Assuming a detector network of three ETs, the analysis shows that
for a 10 SM compact object (CO) inspiralling into a 100 SM IMBH with spin
q=0.3, detected with an SNR of 30, we should be able to determine the CO and
IMBH masses, and the IMBH spin magnitude to fractional accuracies of 0.001,
0.0003, and 0.001, respectively. We also expect to determine the location of
the source in the sky and the luminosity distance to within 0.003 steradians,
and 10%, respectively. We also assess how the precision of parameter
determination depends on the network configuration.Comment: 21 pages, 5 figures. One reference corrected in v3 for consistency
with published version in Phys Rev
Self-forced evolutions of an implicit rotating source: A natural framework to model comparable and intermediate mass-ratio systems from inspiral through ringdown
We develop a waveform model to describe the inspiral, merger and ringdown of
binary systems with comparable and intermediate mass-ratios. This model
incorporates first-order conservative self-force corrections to the energy and
angular momentum, which are valid in the strong-field regime [1]. We model the
radiative part of the self-force by deriving second-order radiative corrections
to the energy flux. These corrections are obtained by minimizing the phase
discrepancy between our self-force model and the effective one body model [2,
3] for a variety of mass-ratios. We show that our model performs substantially
better than post-Newtonian approximants currently used to model neutron
star-black hole mergers from early inspiral to the innermost stable circular
orbit. In order to match the late inspiral evolution onto the plunge regime, we
extend the 'transition phase' developed by Ori and Thorne [4] by including
finite mass-ratio corrections and modelling the orbital phase evolution using
an implicit rotating source [5]. We explicitly show that the implicit rotating
source approach provides a natural transition from late-time radiation to
ringdown that is equivalent to ringdown waveform modelling based on a sum of
quasinormal modes.Comment: 22 pages, 12 figures. Submitted to Phys. Rev. D. v2: Accepted to
Phys. Rev. D. References updated. No correction
Eccentric, nonspinning, inspiral, Gaussian-process merger approximant for the detection and characterization of eccentric binary black hole mergers
We present , a time domain, inspiral-merger-ringdown
waveform model that describes non-spinning binary black holes systems that
evolve on moderately eccentric orbits. The inspiral evolution is described
using a consistent combination of post-Newtonian theory, self-force and black
hole perturbation theory. Assuming eccentric binaries that circularize prior to
coalescence, we smoothly match the eccentric inspiral with a stand-alone,
quasi-circular merger, which is constructed using machine learning algorithms
that are trained with quasi-circular numerical relativity waveforms. We show
that reproduces with excellent accuracy the dynamics of
quasi-circular compact binaries. We validate using a set of
eccentric numerical relativity waveforms, which
describe eccentric binary black hole mergers with mass-ratios between , and eccentricities ten orbits before merger. We
use this model to explore in detail the physics that can be extracted with
moderately eccentric, non-spinning binary black hole mergers. We use
to show that GW150914, GW151226, GW170104, GW170814 and
GW170608 can be effectively recovered with spinning, quasi-circular templates
if the eccentricity of these events at a gravitational wave frequency of 10Hz
satisfies , respectively.
We show that if these systems have eccentricities at a
gravitational wave frequency of 10Hz, they can be misclassified as
quasi-circular binaries due to parameter space degeneracies between
eccentricity and spin corrections. Using our catalog of eccentric numerical
relativity simulations, we discuss the importance of including higher-order
waveform multipoles in gravitational wave searches of eccentric binary black
hole mergers.Comment: 19 pages, 10 figures, 1 Appendix. v2: we use numerical relativity
simulations to quantify the importance of including higher-order waveform
multipoles for the detection of eccentric binary black hole mergers,
references added. Accepted to Phys. Rev.
Can we Detect Intermediate Mass Ratio Inspirals?
Gravitational waves emitted during intermediate-mass-ratio inspirals (IMRIs)
of intermediate-mass black holes (IMBHs) into supermassive black holes could
represent a very interesting source for LISA. Similarly, IMRIs of stellar-mass
compact objects into IMBHs could be detectable by Advanced LIGO. At present,
however, it is not clear what waveforms could be used for IMRI detection, since
the post-Newtonian approximation breaks down as an IMRI approaches the
innermost stable circular orbit, and perturbative solutions are only known to
the lowest order in the mass ratio. We discuss the expected mismatches between
approximate and true waveforms, and the choice of the best available waveform
as a function of the mass ratio and the total mass of the system. We also
comment on the significance of the spin of the smaller body and the need for
its inclusion in the waveforms.Comment: Updated to match published versio
Detecting eccentric supermassive black hole binaries with pulsar timing arrays: Resolvable source strategies
The couplings between supermassive black-hole binaries and their environments
within galactic nuclei have been well studied as part of the search for
solutions to the final parsec problem. The scattering of stars by the binary or
the interaction with a circumbinary disk may efficiently drive the system to
sub-parsec separations, allowing the binary to enter a regime where the
emission of gravitational waves can drive it to merger within a Hubble time.
However, these interactions can also affect the orbital parameters of the
binary. In particular, they may drive an increase in binary eccentricity which
survives until the system's gravitational-wave signal enters the pulsar-timing
array band. Therefore, if we can measure the eccentricity from observed
signals, we can potentially deduce some of the properties of the binary
environment. To this end, we build on previous techniques to present a general
Bayesian pipeline with which we can detect and estimate the parameters of an
eccentric supermassive black-hole binary system with pulsar-timing arrays.
Additionally, we generalize the pulsar-timing array -statistic
to eccentric systems, and show that both this statistic and the Bayesian
pipeline are robust when studying circular or arbitrarily eccentric systems. We
explore how eccentricity influences the detection prospects of single
gravitational-wave sources, as well as the detection penalty incurred by
employing a circular waveform template to search for eccentric signals, and
conclude by identifying important avenues for future study.Comment: 15 pages, 13 figures, 1 table. Accepted for publication in ApJ. New
results on expected binary measurement precisions as a function of
signal-to-noise (Fig 9
Gravitational Waves From Known Pulsars: Results From The Initial Detector Era
We present the results of searches for gravitational waves from a large selection of pulsars using data from the most recent science runs (S6, VSR2 and VSR4) of the initial generation of interferometric gravitational wave detectors LIGO (Laser Interferometric Gravitational-wave Observatory) and Virgo. We do not see evidence for gravitational wave emission from any of the targeted sources but produce upper limits on the emission amplitude. We highlight the results from seven young pulsars with large spin-down luminosities. We reach within a factor of five of the canonical spin-down limit for all seven of these, whilst for the Crab and Vela pulsars we further surpass their spin-down limits. We present new or updated limits for 172 other pulsars (including both young and millisecond pulsars). Now that the detectors are undergoing major upgrades, and, for completeness, we bring together all of the most up-to-date results from all pulsars searched for during the operations of the first-generation LIGO, Virgo and GEO600 detectors. This gives a total of 195 pulsars including the most recent results described in this paper.United States National Science FoundationScience and Technology Facilities Council of the United KingdomMax-Planck-SocietyState of Niedersachsen/GermanyAustralian Research CouncilInternational Science Linkages program of the Commonwealth of AustraliaCouncil of Scientific and Industrial Research of IndiaIstituto Nazionale di Fisica Nucleare of ItalySpanish Ministerio de Economia y CompetitividadConselleria d'Economia Hisenda i Innovacio of the Govern de les Illes BalearsNetherlands Organisation for Scientific ResearchPolish Ministry of Science and Higher EducationFOCUS Programme of Foundation for Polish ScienceRoyal SocietyScottish Funding CouncilScottish Universities Physics AllianceNational Aeronautics and Space AdministrationOTKA of HungaryLyon Institute of Origins (LIO)National Research Foundation of KoreaIndustry CanadaProvince of Ontario through the Ministry of Economic Development and InnovationNational Science and Engineering Research Council CanadaCarnegie TrustLeverhulme TrustDavid and Lucile Packard FoundationResearch CorporationAlfred P. Sloan FoundationAstronom
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 LIGO’s 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
Effects of Data Quality Vetoes on a Search for Compact Binary Coalescences in Advanced LIGO's First Observing Run
The first observing run of Advanced LIGO spanned 4 months, from September 12,
2015 to January 19, 2016, during which gravitational waves were directly
detected from two binary black hole systems, namely GW150914 and GW151226.
Confident detection of gravitational waves requires an understanding of
instrumental transients and artifacts that can reduce the sensitivity of a
search. Studies of the quality of the detector data yield insights into the
cause of instrumental artifacts and data quality vetoes specific to a search
are produced to mitigate the effects of problematic data. In this paper, the
systematic removal of noisy data from analysis time is shown to improve the
sensitivity of searches for compact binary coalescences. The output of the
PyCBC pipeline, which is a python-based code package used to search for
gravitational wave signals from compact binary coalescences, is used as a
metric for improvement. GW150914 was a loud enough signal that removing noisy
data did not improve its significance. However, the removal of data with excess
noise decreased the false alarm rate of GW151226 by more than two orders of
magnitude, from 1 in 770 years to less than 1 in 186000 years.Comment: 27 pages, 13 figures, published versio
Supplement: "Localization and broadband follow-up of the gravitational-wave transient GW150914" (2016, ApJL, 826, L13)
This Supplement provides supporting material for Abbott et al. (2016a). We briefly summarize past electromagnetic (EM) follow-up efforts as well as the organization and policy of the current EM follow-up program. We compare the four probability sky maps produced for the gravitational-wave transient GW150914, and provide additional details of the EM follow-up observations that were performed in the different bands
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