10 research outputs found
Effective-one-body waveforms for binary neutron stars using surrogate models
Gravitational-wave observations of binary neutron star systems can provide
information about the masses, spins, and structure of neutron stars. However,
this requires accurate and computationally efficient waveform models that take
<1s to evaluate for use in Bayesian parameter estimation codes that perform
10^7 - 10^8 waveform evaluations. We present a surrogate model of a nonspinning
effective-one-body waveform model with l = 2, 3, and 4 tidal multipole moments
that reproduces waveforms of binary neutron star numerical simulations up to
merger. The surrogate is built from compact sets of effective-one-body waveform
amplitude and phase data that each form a reduced basis. We find that 12
amplitude and 7 phase basis elements are sufficient to reconstruct any binary
neutron star waveform with a starting frequency of 10Hz. The surrogate has
maximum errors of 3.8% in amplitude (0.04% excluding the last 100M before
merger) and 0.043 radians in phase. The version implemented in the LIGO
Algorithm Library takes ~0.07s to evaluate for a starting frequency of 30Hz and
~0.8s for a starting frequency of 10Hz, resulting in a speed-up factor of ~10^3
- 10^4 relative to the original Matlab code. This allows parameter estimation
codes to run in days to weeks rather than years, and we demonstrate this with a
Nested Sampling run that recovers the masses and tidal parameters of a
simulated binary neutron star system.Comment: 17 pages, 11 figures, submitted to PR
Parameterized tests of the strong-field dynamics of general relativity using gravitational wave signals from coalescing binary black holes: Fast likelihood calculations and sensitivity of the method
Thanks to the recent discoveries of gravitational wave signals from binary
black hole mergers by Advanced Laser Interferometer Gravitational Wave
Observatory and Advanced Virgo, the genuinely strong-field dynamics of
spacetime can now be probed, allowing for stringent tests of general relativity
(GR). One set of tests consists of allowing for parametrized deformations away
from GR in the template waveform models and then constraining the size of the
deviations, as was done for the detected signals in previous work. In this
paper, we construct reduced-order quadratures so as to speed up likelihood
calculations for parameter estimation on future events. Next, we explicitly
demonstrate the robustness of the parametrized tests by showing that they will
correctly indicate consistency with GR if the theory is valid. We also check to
what extent deviations from GR can be constrained as information from an
increasing number of detections is combined. Finally, we evaluate the
sensitivity of the method to possible violations of GR.Comment: 19 pages, many figures. Matches PRD versio
Parametrized tests of the strong-field dynamics of general relativity using gravitational wave signals from coalescing binary black holes: Fast likelihood calculations and sensitivity of the method
Contains fulltext :
184190.pdf (publisher's version ) (Open Access
Empirical tests of the black hole no-hair conjecture using gravitational-wave observations
We show that second-generation gravitational-wave detectors at their design sensitivity will allow us to directly probe the ringdown phase of binary black hole coalescences. This opens the possibility to test the so-called black hole no-hair conjecture in a statistically rigorous way. Using state-of-the-art numerical relativity-tuned waveform models and dedicated methods to effectively isolate the quasistationary perturbative regime where a ringdown description is valid, we demonstrate the capability of measuring the physical parameters of the remnant black hole and subsequently determining parameterized deviations from the ringdown of Kerr black holes. By combining information from O(5) binary black hole mergers with realistic signal-to-noise ratios achievable with the current generation of detectors, the validity of the no-hair conjecture can be verified with an accuracy of similar to 1.5% at 90% confidence
Search for intermediate mass black hole binaries in the first observing run of Advanced LIGO
International audienceDuring their first observational run, the two Advanced LIGO detectors attained an unprecedented sensitivity, resulting in the first direct detections of gravitational-wave signals produced by stellar-mass binary black hole systems. This paper reports on an all-sky search for gravitational waves (GWs) from merging intermediate mass black hole binaries (IMBHBs). The combined results from two independent search techniques were used in this study: the first employs a matched-filter algorithm that uses a bank of filters covering the GW signal parameter space, while the second is a generic search for GW transients (bursts). No GWs from IMBHBs were detected; therefore, we constrain the rate of several classes of IMBHB mergers. The most stringent limit is obtained for black holes of individual mass 100ââMâ, with spins aligned with the binary orbital angular momentum. For such systems, the merger rate is constrained to be less than 0.93ââGpcâ3âyrâ1 in comoving units at the 90%Â confidence level, an improvement of nearly 2 orders of magnitude over previous upper limits
First low-frequency Einstein@Home all-sky search for continuous gravitational waves in Advanced LIGO data
International audienceWe report results of a deep all-sky search for periodic gravitational waves from isolated neutron stars in data from the first Advanced LIGO observing run. This search investigates the low frequency range of Advanced LIGO data, between 20 and 100Â Hz, much of which was not explored in initial LIGO. The search was made possible by the computing power provided by the volunteers of the Einstein@Home project. We find no significant signal candidate and set the most stringent upper limits to date on the amplitude of gravitational wave signals from the target population, corresponding to a sensitivity depth of 48.7ââ[1/Hz]. At the frequency of best strain sensitivity, near 100Â Hz, we set 90% confidence upper limits of 1.8Ă10-25. At the low end of our frequency range, 20Â Hz, we achieve upper limits of 3.9Ă10-24. At 55Â Hz we can exclude sources with ellipticities greater than 10-5 within 100Â pc of Earth with fiducial value of the principal moment of inertia of 1038ââkgâm2
First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data
International audienceSpinning 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 signal-to-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 11Â 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