-
the LIGO Scientific Collaboration,
the Virgo Collaboration,
J. Aasi,
J. Abadie,
B. P. Abbott,
R. Abbott,
T. D. Abbott,
M. Abernathy,
T. Accadia,
F. Acernese, [......],
M. Yvert,
A. Zadrożny,
M. Zanolin,
J. -P. Zendri,
F. Zhang,
L. Zhang,
C. Zhao,
N. Zotov,
M. E. Zucker,
J. Zweizig
[show abstract]
[hide abstract]
ABSTRACT: Compact binary systems with neutron stars or black holes are one of the most
promising sources for ground-based gravitational wave detectors. Gravitational
radiation encodes rich information about source physics; thus parameter
estimation and model selection are crucial analysis steps for any detection
candidate events. Detailed models of the anticipated waveforms enable inference
on several parameters, such as component masses, spins, sky location and
distance that are essential for new astrophysical studies of these sources.
However, accurate measurements of these parameters and discrimination of models
describing the underlying physics are complicated by artifacts in the data,
uncertainties in the waveform models and in the calibration of the detectors.
Here we report such measurements on a selection of simulated signals added
either in hardware or software to the data collected by the two LIGO
instruments and the Virgo detector during their most recent joint science run,
including a "blind injection" where the signal was not initially revealed to
the collaboration. We exemplify the ability to extract information about the
source physics on signals that cover the neutron star and black hole parameter
space over the individual mass range 1 Msun - 25 Msun and the full range of
spin parameters. The cases reported in this study provide a snap-shot of the
status of parameter estimation in preparation for the operation of advanced
detectors.
04/2013;
-
The LIGO Scientific Collaboration,
the Virgo Collaboration,
J. Aasi,
J. Abadie,
B. P. Abbott,
R. Abbott,
T. D. Abbott,
M. Abernathy,
T. Accadia,
F. Acernese, [......],
M. Yvert,
A. Zadrozny,
M. Zanolin,
J. -P. Zendri,
F. Zhang,
L. Zhang,
C. Zhao,
N. Zotov,
M. E. Zucker,
J. Zweizig
[show abstract]
[hide abstract]
ABSTRACT: We report a search for gravitational waves from the inspiral, merger and
ringdown of binary black holes (BBH) with total mass between 25 and 100 solar
masses, in data taken at the LIGO and Virgo observatories between July 7, 2009
and October 20, 2010. The maximum sensitive distance of the detectors over this
period for a (20,20) Msun coalescence was 300 Mpc. No gravitational wave
signals were found. We thus report upper limits on the astrophysical
coalescence rates of BBH as a function of the component masses for non-spinning
components, and also evaluate the dependence of the search sensitivity on
component spins aligned with the orbital angular momentum. We find an upper
limit at 90% confidence on the coalescence rate of BBH with non-spinning
components of mass between 19 and 28 Msun of 3.3 \times 10^-7 mergers /Mpc^3
/yr.
09/2012;
-
J. Aasi,
J. Abadie,
B. P. Abbott,
R. Abbott,
T. D. Abbott,
M. Abernathy,
T. Accadia,
F. Acernese,
C. Adams,
T. Adams, [......],
A. Zadrożny,
M. Zanolin,
J. -P. Zendri,
F. Zhang,
L. Zhang,
C. Zhao,
N. Zotov,
M. E. Zucker,
J. Zweizig,
D. P. Anderson
[show abstract]
[hide abstract]
ABSTRACT: This paper presents results of an all-sky searches for periodic gravitational
waves in the frequency range [50, 1190] Hz and with frequency derivative ranges
of [-2 x 10^-9, 1.1 x 10^-10] Hz/s for the fifth LIGO science run (S5). The
novelty of the search lies in the use of a non-coherent technique based on the
Hough-transform to combine the information from coherent searches on timescales
of about one day. Because these searches are very computationally intensive,
they have been deployed on the Einstein@Home distributed computing project
infrastructure. The search presented here is about a factor 3 more sensitive
than the previous Einstein@Home search in early S5 LIGO data. The
post-processing has left us with eight surviving candidates. We show that
deeper follow-up studies rule each of them out. Hence, since no statistically
significant gravitational wave signals have been detected, we report upper
limits on the intrinsic gravitational wave amplitude h0. For example, in the
0.5 Hz-wide band at 152.5 Hz, we can exclude the presence of signals with h0
greater than 7.6 x 10^-25 with a 90% confidence level.
07/2012;
-
The ANTARES Collaboration,
the LIGO Scientific Collaboration,
the Virgo Collaboration,
S. Adrián-Martínez,
I. Al Samarai,
A. Albert,
M. André,
M. Anghinolfi,
G. Anton,
S. Anvar, [......],
M. Yvert,
A. Zadroźny,
M. Zanolin,
J. -P. Zendri,
F. Zhang,
L. Zhang,
C. Zhao,
N. Zotov,
M. E. Zucker,
J. Zweizig
[show abstract]
[hide abstract]
ABSTRACT: We present the results of the first search for gravitational wave bursts
associated with high energy neutrinos. Together, these messengers could reveal
new, hidden sources that are not observed by conventional photon astronomy,
particularly at high energy. Our search uses neutrinos detected by the
underwater neutrino telescope ANTARES in its 5 line configuration during the
period January - September 2007, which coincided with the fifth and first
science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed
for candidate gravitational-wave signals coincident in time and direction with
the neutrino events. No significant coincident events were observed. We place
limits on the density of joint high energy neutrino - gravitational wave
emission events in the local universe, and compare them with densities of
merger and core-collapse events.
05/2012;
-
The LIGO Scientific Collaboration,
Virgo Collaboration,
J. Abadie,
B. P. Abbott,
R. Abbott,
T. D. Abbott,
M. Abernathy,
T. Accadia,
F. Acernese,
C. Adams, [......],
N. Zotov,
M. E. Zucker,
J. Zweizig,
M. S. Briggs,
V. Connaughton,
K. C. Hurley,
P. A. Jenke,
A. von Kienlin,
A. Rau,
X. -L. Zhang
[show abstract]
[hide abstract]
ABSTRACT: We present the results of a search for gravitational waves associated with
154 gamma-ray bursts (GRBs) that were detected by satellite-based gamma-ray
experiments in 2009-2010, during the sixth LIGO science run and the second and
third Virgo science runs. We perform two distinct searches: a modeled search
for coalescences of either two neutron stars or a neutron star and black hole;
and a search for generic, unmodeled gravitational-wave bursts. We find no
evidence for gravitational-wave counterparts, either with any individual GRB in
this sample or with the population as a whole. For all GRBs we place lower
bounds on the distance to the progenitor, under the optimistic assumption of a
gravitational-wave emission energy of 10^-2 M c^2 at 150 Hz, with a median
limit of 17 Mpc. For short hard GRBs we place exclusion distances on binary
neutron star and neutron star-black hole progenitors, using astrophysically
motivated priors on the source parameters, with median values of 16 Mpc and 28
Mpc respectively. These distance limits, while significantly larger than for a
search that is not aided by GRB satellite observations, are not large enough to
expect a coincidence with a GRB. However, projecting these exclusions to the
sensitivities of Advanced LIGO and Virgo, which should begin operation in 2015,
we find that the detection of gravitational waves associated with GRBs will
become quite possible.
05/2012;
-
P. A. Evans,
J. K. Fridriksson,
N. Gehrels,
J. Homan,
J. P. Osborne,
M. Siegel,
A. Beardmore,
P. Handbauer,
J. Gelbord,
J. A. Kennea, [......],
M. Yvert,
A. Zadrozny,
M. Zanolin,
J. -P. Zendri,
F. Zhang,
L. Zhang,
C. Zhao,
N. Zotov,
M. E. Zucker,
J. Zweizig
[show abstract]
[hide abstract]
ABSTRACT: We present the first multi-wavelength follow-up observations of two candidate
gravitational-wave (GW) transient events recorded by LIGO and Virgo in their
2009-2010 science run. The events were selected with low latency by the network
of GW detectors and their candidate sky locations were observed by the Swift
observatory. Image transient detection was used to analyze the collected
electromagnetic data, which were found to be consistent with background.
Off-line analysis of the GW data alone has also established that the selected
GW events show no evidence of an astrophysical origin; one of them is
consistent with background and the other one was a test, part of a "blind
injection challenge". With this work we demonstrate the feasibility of rapid
follow-ups of GW transients and establish the sensitivity improvement joint
electromagnetic and GW observations could bring. This is a first step toward an
electromagnetic follow-up program in the regime of routine detections with the
advanced GW instruments expected within this decade. In that regime
multi-wavelength observations will play a significant role in completing the
astrophysical identification of GW sources. We present the methods and results
from this first combined analysis and discuss its implications in terms of
sensitivity for the present and future instruments.
05/2012;
-
LIGO Scientific Collaboration,
Virgo Collaboration,
J. Abadie,
B. P. Abbott,
R. Abbott,
T. D. Abbott,
M. Abernathy,
T. Accadia,
F. Acernese,
C. Adams, [......],
R. Fender,
N. Gehrels,
A. Klotz,
E. O. Ofek,
M. Smith,
M. Sokolowski,
B. W. Stappers,
I. Steele,
J. Swinbank,
R. A. M. J. Wijeres
[show abstract]
[hide abstract]
ABSTRACT: Aims: A transient astrophysical event observed in both
gravitational wave (GW) and electromagnetic (EM) channels would yield
rich scientific rewards. A first program initiating EM follow-ups to
possible transient GW events has been developed and exercised by the
LIGO and Virgo community in association with several partners. In this
paper, we describe and evaluate the methods used to promptly identify
and localize GW event candidates and to request images of targeted sky
locations. Methods: During two observing periods (Dec. 17, 2009
to Jan. 8, 2010 and Sep. 2 to Oct. 20, 2010), a low-latency analysis
pipeline was used to identify GW event candidates and to reconstruct
maps of possible sky locations. A catalog of nearby galaxies and Milky
Way globular clusters was used to select the most promising sky
positions to be imaged, and this directional information was delivered
to EM observatories with time lags of about thirty minutes. A Monte
Carlo simulation has been used to evaluate the low-latency GW pipeline's
ability to reconstruct source positions correctly. Results: For
signals near the detection threshold, our low-latency algorithms often
localized simulated GW burst signals to tens of square degrees, while
neutron star/neutron star inspirals and neutron star/black hole
inspirals were localized to a few hundred square degrees. Localization
precision improves for moderately stronger signals. The correct sky
location of signals well above threshold and originating from nearby
galaxies may be observed with ~50% or better probability with a few
pointings of wide-field telescopes.
Astronomy and Astrophysics 03/2012; 539:124. · 4.59 Impact Factor
-
LIGO Scientific Collaboration,
Virgo Collaboration,
J. Abadie,
B. P. Abbott,
R. Abbott,
T. D. Abbott,
M. Abernathy,
T. Accadia,
F. Acernese,
C. Adams, [......],
R. Fender,
N. Gehrels,
A. Klotz,
E. O. Ofek,
M. Smith,
M. Sokolowski,
B. W. Stappers,
I. Steele,
J. Swinbank,
R. A. M. J. Wijeres
[show abstract]
[hide abstract]
ABSTRACT: Aims: A transient astrophysical event observed in both
gravitational wave (GW) and electromagnetic (EM) channels would yield
rich scientific rewards. A first program initiating EM follow-ups to
possible transient GW events has been developed and exercised by the
LIGO and Virgo community in association with several partners. In this
paper, we describe and evaluate the methods used to promptly identify
and localize GW event candidates and to request images of targeted sky
locations. Methods: During two observing periods (Dec. 17, 2009
to Jan. 8, 2010 and Sep. 2 to Oct. 20, 2010), a low-latency analysis
pipeline was used to identify GW event candidates and to reconstruct
maps of possible sky locations. A catalog of nearby galaxies and Milky
Way globular clusters was used to select the most promising sky
positions to be imaged, and this directional information was delivered
to EM observatories with time lags of about thirty minutes. A Monte
Carlo simulation has been used to evaluate the low-latency GW pipeline's
ability to reconstruct source positions correctly. Results: For
signals near the detection threshold, our low-latency algorithms often
localized simulated GW burst signals to tens of square degrees, while
neutron star/neutron star inspirals and neutron star/black hole
inspirals were localized to a few hundred square degrees. Localization
precision improves for moderately stronger signals. The correct sky
location of signals well above threshold and originating from nearby
galaxies may be observed with ~50% or better probability with a few
pointings of wide-field telescopes.
Astronomy and Astrophysics 03/2012; 539:124. · 4.59 Impact Factor
-
J. Aasi,
J. Abadie,
B. P. Abbott,
R. Abbott,
T. D. Abbott,
M. Abernathy,
T. Accadia,
F. Acernese,
C. Adams,
T. Adams, [......],
M. Yvert,
A. Zadrożny,
M. Zanolin,
J. -P. Zendri,
F. Zhang,
L. Zhang,
C. Zhao,
N. Zotov,
M. E. Zucker,
J. Zweizig
[show abstract]
[hide abstract]
ABSTRACT: Between 2007 and 2010 Virgo collected data in coincidence with the LIGO and
GEO gravitational-wave (GW) detectors. These data have been searched for GWs
emitted by cataclysmic phenomena in the universe, by non-axisymmetric rotating
neutron stars or from a stochastic background in the frequency band of the
detectors. The sensitivity of GW searches is limited by noise produced by the
detector or its environment. It is therefore crucial to characterize the
various noise sources in a GW detector. This paper reviews the Virgo detector
noise sources, noise propagation, and conversion mechanisms which were
identified in the three first Virgo observing runs. In many cases, these
investigations allowed us to mitigate noise sources in the detector, or to
selectively flag noise events and discard them from the data. We present
examples from the joint LIGO-GEO-Virgo GW searches to show how well noise
transients and narrow spectral lines have been identified and excluded from the
Virgo data. We also discuss how detector characterization can improve the
astrophysical reach of gravitational-wave searches.
03/2012;
-
the LIGO Scientific Collaboration,
the Virgo Collaboration,
J. Abadie,
B. P. Abbott,
R. Abbott,
T. D. Abbott,
M. Abernathy,
T. Accadia,
F. Acernese,
C. Adams, [......],
A. Zadrozny,
M. Zanolin,
J. -P. Zendri,
F. Zhang,
L. Zhang,
W. Zhang,
C. Zhao,
N. Zotov,
M. E. Zucker,
J. Zweizig
[show abstract]
[hide abstract]
ABSTRACT: We present results from a search for gravitational-wave bursts in the data
collected by the LIGO and Virgo detectors between July 7, 2009 and October 20,
2010: data are analyzed when at least two of the three LIGO-Virgo detectors are
in coincident operation, with a total observation time of 207 days. The
analysis searches for transients of duration < 1 s over the frequency band
64-5000 Hz, without other assumptions on the signal waveform, polarization,
direction or occurrence time. All identified events are consistent with the
expected accidental background. We set frequentist upper limits on the rate of
gravitational-wave bursts by combining this search with the previous LIGO-Virgo
search on the data collected between November 2005 and October 2007. The upper
limit on the rate of strong gravitational-wave bursts at the Earth is 1.3
events per year at 90% confidence. We also present upper limits on source rate
density per year and Mpc^3 for sample populations of standard-candle sources.
As in the previous joint run, typical sensitivities of the search in terms of
the root-sum-squared strain amplitude for these waveforms lie in the range 5
10^-22 Hz^-1/2 to 1 10^-20 Hz^-1/2. The combination of the two joint runs
entails the most sensitive all-sky search for generic gravitational-wave bursts
and synthesizes the results achieved by the initial generation of
interferometric detectors.
02/2012;
-
the LIGO Scientific Collaboration,
the Virgo Collaboration,
J. Abadie,
B. P. Abbott,
R. Abbott,
T. D. Abbott,
M. Abernathy,
T. Accadia,
F. Acernese,
C. Adams, [......],
A. Zadrozny,
M. Zanolin,
J. -P. Zendri,
F. Zhang,
L. Zhang,
W. Zhang,
C. Zhao,
N. Zotov,
M. E. Zucker,
J. Zweizig
[show abstract]
[hide abstract]
ABSTRACT: We present the results of a weakly modeled burst search for gravitational
waves from mergers of non-spinning intermediate mass black holes (IMBH) in the
total mass range 100--450 solar masses and with the component mass ratios
between 1:1 and 4:1. The search was conducted on data collected by the LIGO and
Virgo detectors between November of 2005 and October of 2007. No plausible
signals were observed by the search which constrains the astrophysical rates of
the IMBH mergers as a function of the component masses. In the most efficiently
detected bin centered on 88+88 solar masses, for non-spinning sources, the rate
density upper limit is 0.13 per Mpc^3 per Myr at the 90% confidence level.
01/2012;
-
The LIGO Scientific Collaboration,
J. Abadie,
B. P. Abbott,
T. D. Abbott,
R. Abbott,
M. Abernathy,
C. Adams,
R. Adhikari,
C. Affeldt,
P. Ajith, [......],
L. Zhang,
Z. Zhang,
C. Zhao,
N. Zotov,
M. E. Zucker,
J. Zweizig,
M. A. Bizouard,
A. Dietz,
G. M. Guidi,
M. Was
[show abstract]
[hide abstract]
ABSTRACT: We present the results of a LIGO search for gravitational waves (GWs)
associated with GRB 051103, a short-duration hard-spectrum gamma-ray burst
(GRB) whose electromagnetically determined sky position is coincident with the
spiral galaxy M81, which is 3.6 Mpc from Earth. Possible progenitors for
short-hard GRBs include compact object mergers and soft gamma repeater (SGR)
giant flares. A merger progenitor would produce a characteristic GW signal that
should be detectable at the distance of M81, while GW emission from an SGR is
not expected to be detectable at that distance. We found no evidence of a GW
signal associated with GRB 051103. Assuming weakly beamed gamma-ray emission
with a jet semi-angle of 30 deg we exclude a binary neutron star merger in M81
as the progenitor with a confidence of 98%. Neutron star-black hole mergers are
excluded with > 99% confidence. If the event occurred in M81 our findings
support the the hypothesis that GRB 051103 was due to an SGR giant flare,
making it the most distant extragalactic magnetar observed to date.
01/2012;
-
J. Abadie,
B. P. Abbott,
R. Abbott,
M. Abernathy,
T. Accadia,
F. Acernese,
C. Adams,
R. Adhikari,
P. Ajith,
B. Allen, [......],
S. Yoshida,
P. Yu,
M. Yvert,
M. Zanolin,
L. Zhang,
Z. Zhang,
C. Zhao,
N. Zotov,
M. E. Zucker,
J. Zweizig
[show abstract]
[hide abstract]
ABSTRACT: Abadie, J. Abbott, B. P. Abbott, R. Abernathy, M. Accadia, T. Acernese, F. Adams, C. Adhikari, R. Ajith, P. Allen, B. Allen, G. S. Ceron, E. Amador Amin, R. S. Anderson, S. B. Anderson, W. G. Antonucci, F. Arain, M. A. Araya, M. C. Aronsson, M. Aso, Y. Aston, S. M. Astone, P. Atkinson, D. Aufmuth, P. Aulbert, C. Babak, S. Baker, P. Ballardin, G. Ballinger, T. Ballmer, S. Barker, D. Barnum, S. Barone, F. Barr, B. Barriga, P. Barsotti, L. Barsuglia, M. Barton, M. A. Bartos, I. Bassiri, R. Bastarrika, M. Bauchrowitz, J. Bauer, Th. S. Behnke, B. Beker, M. G. Belletoile, A. Benacquista, M. Bertolini, A. Betzwieser, J. Beveridge, N. Beyersdorf, P. T. Bilenko, I. A. Billingsley, G. Birch, J. Birindelli, S. Biswas, R. Bitossi, M. Bizouard, M. A. Black, E. Blackburn, J. K. Blackburn, L. Blair, D. Bland, B. Blom, M. Boccara, C. Bock, O. Bodiya, T. P. Bondarescu, R. Bondu, F. Bonelli, L. Bonnand, R. Bork, R. Born, M. Boschi, V. Bose, S. Bosi, L. Bouhou, B. Boyle, M. Braccini, S. Bradaschia, C. Brady, P. R. Bragin
Physical Review D 01/2012; 85. · 4.56 Impact Factor
-
J. Abadie,
B. P. Abbott,
R. Abbott,
M. Abernathy,
T. Accadia,
F. Acernese,
C. Adams,
R. Adhikari,
P. Ajith,
B. Allen, [......],
S. Yoshida,
P. P. Yu,
M. Yvert,
M. Zanolin,
L. Zhang,
Z. Zhang,
C. Zhao,
N. Zotov,
M. E. Zucker,
J. Zweizig
[show abstract]
[hide abstract]
ABSTRACT: Abadie, J. Abbott, B. P. Abbott, R. Abernathy, M. Accadia, T. Acernese, F. Adams, C. Adhikari, R. Ajith, P. Allen, B. Allen, G. Ceron, E. Amador Amin, R. S. Anderson, S. B. Anderson, W. G. Antonucci, F. Arain, M. A. Araya, M. Aronsson, M. Arun, K. G. Aso, Y. Aston, S. Astone, P. Atkinson, D. E. Aufmuth, P. Aulbert, C. Babak, S. Baker, P. Ballardin, G. Ballinger, T. Ballmer, S. Barker, D. Barnum, S. Barone, F. Barr, B. Barriga, P. Barsotti, L. Barsuglia, M. Barton, M. A. Bartos, I. Bassiri, R. Bastarrika, M. Bauchrowitz, J. Bauer, Th. S. Behnke, B. Beker, M. G. Belletoile, A. Benacquista, M. Bertolini, A. Betzwieser, J. Beveridge, N. Beyersdorf, P. T. Bigotta, S. Bilenko, I. A. Billingsley, G. Birch, J. Birindelli, S. Biswas, R. Bitossi, M. Bizouard, M. A. Black, E. Blackburn, J. K. Blackburn, L. Blair, D. Bland, B. Blom, M. Boccara, C. Bock, O. Bodiya, T. P. Bondarescu, R. Bondu, F. Bonelli, L. Bonnand, R. Bork, R. Born, M. Bose, S. Bosi, L. Bouhou, B. Boyle, M. Braccini, S. Bradaschia, C. Brady, P. R.
Physical Review D 01/2012; 85. · 4.56 Impact Factor
-
J. Abadie,
B. P. Abbott,
R. Abbott,
M. Abernathy,
T. Accadia,
F. Acernese,
C. Adams,
R. Adhikari,
P. Ajith,
B. Allen, [......],
S. Yoshida,
P. P. Yu,
M. Yvert,
M. Zanolin,
L. Zhang,
Z. Zhang,
C. Zhao,
N. Zotov,
M. E. Zucker,
J. Zweizig
[show abstract]
[hide abstract]
ABSTRACT: Abadie, J. Abbott, B. P. Abbott, R. Abernathy, M. Accadia, T. Acernese, F. Adams, C. Adhikari, R. Ajith, P. Allen, B. Allen, G. Ceron, E. Amador Amin, R. S. Anderson, S. B. Anderson, W. G. Antonucci, F. Arain, M. A. Araya, M. Aronsson, M. Arun, K. G. Aso, Y. Aston, S. Astone, P. Atkinson, D. E. Aufmuth, P. Aulbert, C. Babak, S. Baker, P. Ballardin, G. Ballinger, T. Ballmer, S. Barker, D. Barnum, S. Barone, F. Barr, B. Barriga, P. Barsotti, L. Barsuglia, M. Barton, M. A. Bartos, I. Bassiri, R. Bastarrika, M. Bauchrowitz, J. Bauer, Th. S. Behnke, B. Beker, M. G. Belletoile, A. Benacquista, M. Bertolini, A. Betzwieser, J. Beveridge, N. Beyersdorf, P. T. Bigotta, S. Bilenko, I. A. Billingsley, G. Birch, J. Birindelli, S. Biswas, R. Bitossi, M. Bizouard, M. A. Black, E. Blackburn, J. K. Blackburn, L. Blair, D. Bland, B. Blom, M. Boccara, C. Bock, O. Bodiya, T. P. Bondarescu, R. Bondu, F. Bonelli, L. Bonnand, R. Bork, R. Born, M. Bose, S. Bosi, L. Bouhou, B. Boyle, M. Braccini, S. Bradaschia, C. Brady, P. R.
Physical Review D 01/2012; 85. · 4.56 Impact Factor
-
J Abadie,
B P Abbott,
R Abbott,
M Abernathy,
T Accadia,
F Acernese,
C Adams,
R Adhikari,
P Ajith,
B Allen, [......],
S Yoshida,
P Yu,
M Yvert,
M Zanolin,
L Zhang,
Z Zhang,
C Zhao,
N Zotov,
M E Zucker,
J Zweizig
[show abstract]
[hide abstract]
ABSTRACT: The gravitational-wave (GW) sky may include nearby pointlike sources as well as stochastic backgrounds. We perform two directional searches for persistent GWs using data from the LIGO S5 science run: one optimized for pointlike sources and one for arbitrary extended sources. Finding no evidence to support the detection of GWs, we present 90% confidence level (C.L.) upper-limit maps of GW strain power with typical values between 2-20×10(-50) strain(2) Hz(-1) and 5-35×10(-49) strain(2) Hz(-1) sr(-1) for pointlike and extended sources, respectively. The latter result is the first of its kind. We also set 90% C.L. limits on the narrow-band root-mean-square GW strain from interesting targets including Sco X-1, SN 1987A and the Galactic center as low as ≈7×10(-25) in the most sensitive frequency range near 160 Hz.
Physical Review Letters 12/2011; 107(27):271102. · 7.37 Impact Factor
-
J. Abadie,
B. P. Abbott,
R. Abbott,
T. D. Abbott,
M. Abernathy,
T. Accadia,
F. Acernese,
C. Adams,
R. Adhikari,
C. Affeldt, [......],
A. Zadroźny,
M. Zanolin,
J. -P. Zendri,
F. Zhang,
L. Zhang,
W. Zhang,
C. Zhao,
N. Zotov,
M. E. Zucker,
J. Zweizig
[show abstract]
[hide abstract]
ABSTRACT: A stochastic background of gravitational waves is expected to arise from a
superposition of many incoherent sources of gravitational waves, of either
cosmological or astrophysical origin. This background is a target for the
current generation of ground-based detectors. In this article we present the
first joint search for a stochastic background using data from the LIGO and
Virgo interferometers. In a frequency band of 600-1000 Hz, we obtained a 95%
upper limit on the amplitude of $\Omega_{\rm GW}(f) = \Omega_3 (f/900
\mathrm{Hz})^3$, of $\Omega_3 < 0.33$, assuming a value of the Hubble parameter
of $h_{100}=0.72$. These new limits are a factor of seven better than the
previous best in this frequency band.
12/2011;
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the LIGO Scientific Collaboration,
the Virgo Collaboration,
J. Abadie,
B. P. Abbott,
R. Abbott,
T. D. Abbott,
M. Abernathy,
T. Accadia,
F. Acernese,
C. Adams, [......],
M. Zanolin,
J. -P. Zendri,
F. Zhang,
L. Zhang,
W. Zhang,
Z. Zhang,
C. Zhao,
N. Zotov,
M. E. Zucker,
J. Zweizig
[show abstract]
[hide abstract]
ABSTRACT: We report on a search for gravitational waves from coalescing compact
binaries using LIGO and Virgo observations between July 7, 2009 and October 20,
2010. We searched for signals from binaries with total mass between 2 and 25
solar masses; this includes binary neutron stars, binary black holes, and
binaries consisting of a black hole and neutron star. The detectors were
sensitive to systems up to 40 Mpc distant for binary neutron stars, and further
for higher mass systems. No gravitational-wave signals were detected. We report
upper limits on the rate of compact binary coalescence as a function of total
mass, including the results from previous LIGO and Virgo observations. The
cumulative 90%-confidence rate upper limits of the binary coalescence of binary
neutron star, neutron star- black hole and binary black hole systems are 1.3 x
10^{-4}, 3.1 x 10^{-5} and 6.4 x 10^{-6} Mpc^{-3}yr^{-1}, respectively. These
upper limits are up to a factor 1.4 lower than previously derived limits. We
also report on results from a blind injection challenge.
11/2011;
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J. Abadie,
B. P. Abbott,
R Abbott,
T. D. Abbott,
M. Abernathy,
T. Accadia,
F. Acernese,
C Adams,
R. Adhikari,
C. Affeldt, [......],
M. Zanolin,
J. P. Zendri,
F Zhang,
L Zhang,
W Zhang,
Z Zhang,
C Zhao,
N. Zotov,
M. E. Zucker,
J. Zweizig
[show abstract]
[hide abstract]
ABSTRACT: We report on an all-sky search for periodic gravitational waves in the frequency band 50-800 Hz and with the frequency time derivative in the range of 0 through -6×10-9Hz/s. Such a signal could be produced by a nearby spinning and slightly nonaxisymmetric isolated neutron star in our Galaxy. After recent improvements in the search program that yielded a 10× increase in computational efficiency, we have searched in two years of data collected during LIGO’s fifth science run and have obtained the most sensitive all-sky upper limits on gravitational-wave strain to date. Near 150 Hz our upper limit on worst-case linearly polarized strain amplitude h0 is 1×10-24, while at the high end of our frequency range we achieve a worst-case upper limit of 3.8×10-24 for all polarizations and sky locations. These results constitute a factor of 2 improvement upon previously published data. A new detection pipeline utilizing a loosely coherent algorithm was able to follow up weaker outliers, increasing the volume of space where signals can be detected by a factor of 10, but has not revealed any gravitational-wave signals. The pipeline has been tested for robustness with respect to deviations from the model of an isolated neutron star, such as caused by a low-mass or long-period binary companion.
Physical Review D 10/2011; 85(2):022001. · 4.56 Impact Factor
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The LIGO Scientific Collaboration,
Virgo Collaboration,
J. Abadie,
B. P. Abbott,
R. Abbott,
T. D. Abbott,
M. Abernathy,
T. Accadia,
F. Acernese,
C. Adams, [......],
N. Gehrels,
A. Klotz,
E. O. Ofek,
M. Smith,
M. Sokolowski,
B. W. Stappers,
I. Steele,
J. Swinbank,
R. A. M. J. Wijers,
W. Zheng
[show abstract]
[hide abstract]
ABSTRACT: Aims. A transient astrophysical event observed in both gravitational wave
(GW) and electromagnetic (EM) channels would yield rich scientific rewards. A
first program initiating EM follow-ups to possible transient GW events has been
developed and exercised by the LIGO and Virgo community in association with
several partners. In this paper, we describe and evaluate the methods used to
promptly identify and localize GW event candidates and to request images of
targeted sky locations.
Methods. During two observing periods (Dec 17 2009 to Jan 8 2010 and Sep 2 to
Oct 20 2010), a low-latency analysis pipeline was used to identify GW event
candidates and to reconstruct maps of possible sky locations. A catalog of
nearby galaxies and Milky Way globular clusters was used to select the most
promising sky positions to be imaged, and this directional information was
delivered to EM observatories with time lags of about thirty minutes. A Monte
Carlo simulation has been used to evaluate the low-latency GW pipeline's
ability to reconstruct source positions correctly.
Results. For signals near the detection threshold, our low-latency algorithms
often localized simulated GW burst signals to tens of square degrees, while
neutron star/neutron star inspirals and neutron star/black hole inspirals were
localized to a few hundred square degrees. Localization precision improves for
moderately stronger signals. The correct sky location of signals well above
threshold and originating from nearby galaxies may be observed with ~50% or
better probability with a few pointings of wide-field telescopes.
09/2011;
