13 research outputs found
The Timing System of LIGO Discoveries
LIGO's mission critical timing system has enabled gravitational wave and
multi-messenger astrophysical discoveries as well as the rich science
extracted. Achieving optimal detector sensitivity, detecting transient
gravitational waves, and especially localizing gravitational wave sources, the
underpinning of multi-messenger astrophysics, all require proper gravitational
wave data time-stamping. Measurements of the relative arrival times of
gravitational waves between different detectors allow for coherent
gravitational wave detections, localization of gravitational wave sources, and
the creation of skymaps. The carefully designed timing system achieves these
goals by mitigating phase noise to avoid signal up-conversion and maximize
gravitational wave detector sensitivity. The timing system also redundantly
performs self-calibration and self-diagnostics in order to ensure reliable,
extendable, and traceable time stamping. In this paper, we describe and
quantify the performance of these core systems during the latest O3 scientific
run of LIGO, Virgo, and KAGRA. We present results of the diagnostic checks done
to verify the time-stamping for individual gravitational wave events observed
during O3 as well as the timing system performance for all of O3 in LIGO
Livingston and LIGO Hanford. We find that, after 3 observing runs, the LIGO
timing system continues to reliably meet mission requirements of timing
precision below 1 s with a significant safety margin.Comment: 11 pages, 8 figure
The US Program in Ground-Based Gravitational Wave Science: Contribution from the LIGO Laboratory
Recent gravitational-wave observations from the LIGO and Virgo observatories have brought a sense of great excitement to scientists and citizens the world over. Since September 2015,10 binary black hole coalescences and one binary neutron star coalescence have been observed. They have provided remarkable, revolutionary insight into the "gravitational Universe" and have greatly extended the field of multi-messenger astronomy. At present, Advanced LIGO can see binary black hole coalescences out to redshift 0.6 and binary neutron star coalescences to redshift 0.05. This probes only a very small fraction of the volume of the observable Universe. However, current technologies can be extended to construct "3rd Generation" (3G) gravitational-wave observatories that would extend our reach to the very edge of the observable Universe. The event rates over such a large volume would be in the hundreds of thousands per year (i.e. tens per hour). Such 3G detectors would have a 10-fold improvement in strain sensitivity over the current generation of instruments, yielding signal-to-noise ratios of 1000 for events like those already seen. Several concepts are being studied for which engineering studies and reliable cost estimates will be developed in the next 5 years
Point absorbers in Advanced LIGO
Small, highly absorbing points are randomly present on the surfaces of the
main interferometer optics in Advanced LIGO. The resulting nano-meter scale
thermo-elastic deformations and substrate lenses from these micron-scale
absorbers significantly reduces the sensitivity of the interferometer directly
though a reduction in the power-recycling gain and indirect interactions with
the feedback control system. We review the expected surface deformation from
point absorbers and provide a pedagogical description of the impact on power
build-up in second generation gravitational wave detectors (dual-recycled
Fabry-Perot Michelson interferometers). This analysis predicts that the
power-dependent reduction in interferometer performance will significantly
degrade maximum stored power by up to 50% and hence, limit GW sensitivity, but
suggests system wide corrections that can be implemented in current and future
GW detectors. This is particularly pressing given that future GW detectors call
for an order of magnitude more stored power than currently used in Advanced
LIGO in Observing Run 3. We briefly review strategies to mitigate the effects
of point absorbers in current and future GW wave detectors to maximize the
success of these enterprises.Comment: 49 pages, 16 figures. -V2: typographical errors in equations B9 and
B10 were corrected (stray exponent of "h" was removed). Caption of Figure 9
was corrected to indicate that 40mW was used for absorption in the model, not
10mW as incorrectly indicated in V
The population of merging compact binaries inferred using gravitational waves through GWTC-3
v2: minor edits, most to Table 1 and caption; v3: rerun with public data; Data release: https://zenodo.org/record/5655785; v4: update Fig 14We report on the population properties of 76 compact binary mergers detected with gravitational waves below a false alarm rate of 1 per year through GWTC-3. The catalog contains three classes of binary mergers: BBH, BNS, and NSBH mergers. We infer the BNS merger rate to be between 10 and 1700 and the NSBH merger rate to be between 7.8 and 140 , assuming a constant rate density versus comoving volume and taking the union of 90% credible intervals for methods used in this work. Accounting for the BBH merger rate to evolve with redshift, we find the BBH merger rate to be between 17.9 and 44 at a fiducial redshift (z=0.2). We obtain a broad neutron star mass distribution extending from to . We can confidently identify a rapid decrease in merger rate versus component mass between neutron star-like masses and black-hole-like masses, but there is no evidence that the merger rate increases again before 10 . We also find the BBH mass distribution has localized over- and under-densities relative to a power law distribution. While we continue to find the mass distribution of a binary's more massive component strongly decreases as a function of primary mass, we observe no evidence of a strongly suppressed merger rate above . The rate of BBH mergers is observed to increase with redshift at a rate proportional to with for . Observed black hole spins are small, with half of spin magnitudes below . We observe evidence of negative aligned spins in the population, and an increase in spin magnitude for systems with more unequal mass ratio
The population of merging compact binaries inferred using gravitational waves through GWTC-3
v2: minor edits, most to Table 1 and caption; v3: rerun with public data; Data release: https://zenodo.org/record/5655785; v4: update Fig 14We report on the population properties of 76 compact binary mergers detected with gravitational waves below a false alarm rate of 1 per year through GWTC-3. The catalog contains three classes of binary mergers: BBH, BNS, and NSBH mergers. We infer the BNS merger rate to be between 10 and 1700 and the NSBH merger rate to be between 7.8 and 140 , assuming a constant rate density versus comoving volume and taking the union of 90% credible intervals for methods used in this work. Accounting for the BBH merger rate to evolve with redshift, we find the BBH merger rate to be between 17.9 and 44 at a fiducial redshift (z=0.2). We obtain a broad neutron star mass distribution extending from to . We can confidently identify a rapid decrease in merger rate versus component mass between neutron star-like masses and black-hole-like masses, but there is no evidence that the merger rate increases again before 10 . We also find the BBH mass distribution has localized over- and under-densities relative to a power law distribution. While we continue to find the mass distribution of a binary's more massive component strongly decreases as a function of primary mass, we observe no evidence of a strongly suppressed merger rate above . The rate of BBH mergers is observed to increase with redshift at a rate proportional to with for . Observed black hole spins are small, with half of spin magnitudes below . We observe evidence of negative aligned spins in the population, and an increase in spin magnitude for systems with more unequal mass ratio
The population of merging compact binaries inferred using gravitational waves through GWTC-3
v2: minor edits, most to Table 1 and caption; v3: rerun with public data; Data release: https://zenodo.org/record/5655785; v4: update Fig 14We report on the population properties of 76 compact binary mergers detected with gravitational waves below a false alarm rate of 1 per year through GWTC-3. The catalog contains three classes of binary mergers: BBH, BNS, and NSBH mergers. We infer the BNS merger rate to be between 10 and 1700 and the NSBH merger rate to be between 7.8 and 140 , assuming a constant rate density versus comoving volume and taking the union of 90% credible intervals for methods used in this work. Accounting for the BBH merger rate to evolve with redshift, we find the BBH merger rate to be between 17.9 and 44 at a fiducial redshift (z=0.2). We obtain a broad neutron star mass distribution extending from to . We can confidently identify a rapid decrease in merger rate versus component mass between neutron star-like masses and black-hole-like masses, but there is no evidence that the merger rate increases again before 10 . We also find the BBH mass distribution has localized over- and under-densities relative to a power law distribution. While we continue to find the mass distribution of a binary's more massive component strongly decreases as a function of primary mass, we observe no evidence of a strongly suppressed merger rate above . The rate of BBH mergers is observed to increase with redshift at a rate proportional to with for . Observed black hole spins are small, with half of spin magnitudes below . We observe evidence of negative aligned spins in the population, and an increase in spin magnitude for systems with more unequal mass ratio
The population of merging compact binaries inferred using gravitational waves through GWTC-3
v2: minor edits, most to Table 1 and caption; v3: rerun with public data; Data release: https://zenodo.org/record/5655785; v4: update Fig 14We report on the population properties of 76 compact binary mergers detected with gravitational waves below a false alarm rate of 1 per year through GWTC-3. The catalog contains three classes of binary mergers: BBH, BNS, and NSBH mergers. We infer the BNS merger rate to be between 10 and 1700 and the NSBH merger rate to be between 7.8 and 140 , assuming a constant rate density versus comoving volume and taking the union of 90% credible intervals for methods used in this work. Accounting for the BBH merger rate to evolve with redshift, we find the BBH merger rate to be between 17.9 and 44 at a fiducial redshift (z=0.2). We obtain a broad neutron star mass distribution extending from to . We can confidently identify a rapid decrease in merger rate versus component mass between neutron star-like masses and black-hole-like masses, but there is no evidence that the merger rate increases again before 10 . We also find the BBH mass distribution has localized over- and under-densities relative to a power law distribution. While we continue to find the mass distribution of a binary's more massive component strongly decreases as a function of primary mass, we observe no evidence of a strongly suppressed merger rate above . The rate of BBH mergers is observed to increase with redshift at a rate proportional to with for . Observed black hole spins are small, with half of spin magnitudes below . We observe evidence of negative aligned spins in the population, and an increase in spin magnitude for systems with more unequal mass ratio
Model comparison from LIGO–Virgo data on GW170817’s binary components and consequences for the merger remnant
International audienceGW170817 is the very first observation of gravitational waves originating from the coalescence of two compact objects in the mass range of neutron stars, accompanied by electromagnetic counterparts, and offers an opportunity to directly probe the internal structure of neutron stars. We perform Bayesian model selection on a wide range of theoretical predictions for the neutron star equation of state. For the binary neutron star hypothesis, we find that we cannot rule out the majority of theoretical models considered. In addition, the gravitational-wave data alone does not rule out the possibility that one or both objects were low-mass black holes. We discuss the possible outcomes in the case of a binary neutron star merger, finding that all scenarios from prompt collapse to long-lived or even stable remnants are possible. For long-lived remnants, we place an upper limit of 1.9 kHz on the rotation rate. If a black hole was formed any time after merger and the coalescing stars were slowly rotating, then the maximum baryonic mass of non-rotating neutron stars is at most , and three equations of state considered here can be ruled out. We obtain a tighter limit of for the case that the merger results in a hypermassive neutron star