166 research outputs found
Search for post-merger gravitational waves from the remnant of the binary neutron star merger GW170817
In Advanced LIGO, detection and astrophysical source parameter estimation of the binary black hole merger GW150914 requires a calibrated estimate of the gravitational-wave strain sensed by the detectors. Producing an estimate from each detector's differential arm length control loop readout signals requires applying time domain filters, which are designed from a frequency domain model of the detector's gravitational-wave response. The gravitational-wave response model is determined by the detector's opto-mechanical response and the properties of its feedback control system. The measurements used to validate the model and characterize its uncertainty are derived primarily from a dedicated photon radiation pressure actuator, with cross-checks provided by optical and radio frequency references. We describe how the gravitational-wave readout signal is calibrated into equivalent gravitational-wave-induced strain and how the statistical uncertainties and systematic errors are assessed. Detector data collected over 38 calendar days, from September 12 to October 20, 2015, contain the event GW150914 and approximately 16 of coincident data used to estimate the event false alarm probability. The calibration uncertainty is less than 10% in magnitude and 10 degrees in phase across the relevant frequency band 20 Hz to 1 kHz
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
A search of the Orion spur for continuous gravitational waves using a "loosely coherent" algorithm on data from LIGO interferometers
We report results of a wideband search for periodic gravitational waves from
isolated neutron stars within the Orion spur towards both the inner and outer
regions of our Galaxy. As gravitational waves interact very weakly with matter,
the search is unimpeded by dust and concentrations of stars. One search disk
(A) is in diameter and centered on
, and the other
(B) is in diameter and centered on
. We explored the
frequency range of 50-1500 Hz and frequency derivative from to Hz/s. A multi-stage, loosely coherent search program allowed probing
more deeply than before in these two regions, while increasing coherence length
with every stage.
Rigorous followup parameters have winnowed initial coincidence set to only 70
candidates, to be examined manually. None of those 70 candidates proved to be
consistent with an isolated gravitational wave emitter, and 95% confidence
level upper limits were placed on continuous-wave strain amplitudes. Near
Hz we achieve our lowest 95% CL upper limit on worst-case linearly polarized
strain amplitude of , while at the high end of our
frequency range we achieve a worst-case upper limit of for
all polarizations and sky locations.Comment: Fixed minor typo - duplicate name in the author lis
Search of the Orion spur for continuous gravitational waves using a loosely coherent algorithm on data from LIGO interferometers
We report results of a wideband search for periodic gravitational waves from isolated neutron stars within the Orion spur towards both the inner and outer regions of our Galaxy. As gravitational waves interact very weakly with matter, the search is unimpeded by dust and concentrations of stars. One search disk (A) is 6.87° in diameter and centered on 20h10m54.71s+33°33′25.29′′, and the other (B) is 7.45° in diameter and centered on 8h35m20.61s-46°49′25.151′′. We explored the frequency range of 50-1500 Hz and frequency derivative from 0 to -5×10-9 Hz/s. A multistage, loosely coherent search program allowed probing more deeply than before in these two regions, while increasing coherence length with every stage. Rigorous follow-up parameters have winnowed the initial coincidence set to only 70 candidates, to be examined manually. None of those 70 candidates proved to be consistent with an isolated gravitational-wave emitter, and 95% confidence level upper limits were placed on continuous-wave strain amplitudes. Near 169 Hz we achieve our lowest 95% C.L. upper limit on the worst-case linearly polarized strain amplitude h0 of 6.3×10-25, while at the high end of our frequency range we achieve a worst-case upper limit of 3.4×10-24 for all polarizations and sky locations. © 2016 American Physical Society
First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data
In Advanced LIGO, detection and astrophysical source parameter estimation of the binary black hole merger GW150914 requires a calibrated estimate of the gravitational-wave strain sensed by the detectors. Producing an estimate from each detector's differential arm length control loop readout signals requires applying time domain filters, which are designed from a frequency domain model of the detector's gravitational-wave response. The gravitational-wave response model is determined by the detector's opto-mechanical response and the properties of its feedback control system. The measurements used to validate the model and characterize its uncertainty are derived primarily from a dedicated photon radiation pressure actuator, with cross-checks provided by optical and radio frequency references. We describe how the gravitational-wave readout signal is calibrated into equivalent gravitational-wave-induced strain and how the statistical uncertainties and systematic errors are assessed. Detector data collected over 38 calendar days, from September 12 to October 20, 2015, contain the event GW150914 and approximately 16 of coincident data used to estimate the event false alarm probability. The calibration uncertainty is less than 10% in magnitude and 10 degrees in phase across the relevant frequency band 20 Hz to 1 kHz
Searches for continuous gravitational waves from nine young supernova remnants
We describe directed searches for continuous gravitational waves in data from
the sixth LIGO science data run. The targets were nine young supernova remnants
not associated with pulsars; eight of the remnants are associated with
non-pulsing suspected neutron stars. One target's parameters are uncertain
enough to warrant two searches, for a total of ten. Each search covered a broad
band of frequencies and first and second frequency derivatives for a fixed sky
direction. The searches coherently integrated data from the two LIGO
interferometers over time spans from 5.3-25.3 days using the matched-filtering
F-statistic. We found no credible gravitational-wave signals. We set 95%
confidence upper limits as strong (low) as on intrinsic
strain, on fiducial ellipticity, and on
r-mode amplitude. These beat the indirect limits from energy conservation and
are within the range of theoretical predictions for neutron-star ellipticities
and r-mode amplitudes.Comment: Science summary available at
http://www.ligo.org/science/Publication-S6DirectedSNR/index.ph
Multimessenger Search for Sources of Gravitational Waves and High-Energy Neutrinos: Results for Initial LIGO-Virgo and IceCube
We report the results of a multimessenger search for coincident signals from
the LIGO and Virgo gravitational-wave observatories and the partially completed
IceCube high-energy neutrino detector, including periods of joint operation
between 2007-2010. These include parts of the 2005-2007 run and the 2009-2010
run for LIGO-Virgo, and IceCube's observation periods with 22, 59 and 79
strings. We find no significant coincident events, and use the search results
to derive upper limits on the rate of joint sources for a range of source
emission parameters. For the optimistic assumption of gravitational-wave
emission energy of \,Mc at \,Hz with \,ms duration, and high-energy neutrino emission of \,erg
comparable to the isotropic gamma-ray energy of gamma-ray bursts, we limit the
source rate below \,Mpcyr. We also examine
how combining information from gravitational waves and neutrinos will aid
discovery in the advanced gravitational-wave detector era
Improved upper limits on the stochastic gravitational-wave background from 2009-2010 LIGO and Virgo data
Paper producido por "The LIGO Scientific Collaboration and the Virgo Collaboration". (En el registro se mencionan solo algunos autores de las decenas de personas que participan).Gravitational waves from a variety of sources are predicted to superpose to create a stochastic
background. This background is expected to contain unique information from throughout the history of
the Universe that is unavailable through standard electromagnetic observations, making its study of
fundamental importance to understanding the evolution of the Universe. We carry out a search for the
stochastic background with the latest data from the LIGO and Virgo detectors. Consistent with predictions from most stochastic gravitational-wave background models, the data display no evidence of a stochastic gravitational-wave signal. Assuming a gravitational-wave spectrum of ΩGWðfÞ ¼ Ωαðf=frefÞα, we place 95% confidence level upper limits on the energy density of the background in each of four frequency bands spanning 41.5–1726 Hz. In the frequency band of 41.5–169.25 Hz for a spectral index of α¼ 0, we constrain the energy density of the stochastic background to be ΩGWðfÞ <5.6 × 10−6. For the 600–1000 Hz band, ΩGWðfÞ <0.14ðf=900 HzÞ3, a factor of 2.5 lower than the best previously reported upper limits. We find ΩGWðfÞ <1.8 × 10−4 using a spectral index of zero for 170–600 Hz and ΩGWðfÞ < 1.0ðf=1300 HzÞ3 for 1000–1726 Hz, bands in which no previous direct limits have been placed. The limits in these four bands are the lowest direct measurements to date on the stochastic background. We discuss the implications of these results in light of the recent claim by the BICEP2 experiment of the possible evidence for inflationary gravitational waves.http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.113.231101publishedVersionFil: Aasi, J. LIGO. California Institute of Technology; Estados Unidos de América.Fil: Maglione, C. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Maglione, C. Argentinian Gravitational Wave Group; Argentina.Fil: Quiroga, G. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Quiroga, G. Argentinian Gravitational Wave Group; Argentina.Física de Partículas y Campo
First all-sky search for continuous gravitational waves from unknown sources in binary systems
We present the first results of an all-sky search for continuous
gravitational waves from unknown spinning neutron stars in binary systems using
LIGO and Virgo data. Using a specially developed analysis program, the TwoSpect
algorithm, the search was carried out on data from the sixth LIGO Science Run
and the second and third Virgo Science Runs. The search covers a range of
frequencies from 20 Hz to 520 Hz, a range of orbital periods from 2 to ~2,254 h
and a frequency- and period-dependent range of frequency modulation depths from
0.277 to 100 mHz. This corresponds to a range of projected semi-major axes of
the orbit from ~0.6e-3 ls to ~6,500 ls assuming the orbit of the binary is
circular. While no plausible candidate gravitational wave events survive the
pipeline, upper limits are set on the analyzed data. The most sensitive 95%
confidence upper limit obtained on gravitational wave strain is 2.3e-24 at 217
Hz, assuming the source waves are circularly polarized. Although this search
has been optimized for circular binary orbits, the upper limits obtained remain
valid for orbital eccentricities as large as 0.9. In addition, upper limits are
placed on continuous gravitational wave emission from the low-mass x-ray binary
Scorpius X-1 between 20 Hz and 57.25 Hz.Comment: 16 pages, 6 figure
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