52 research outputs found
First LIGO search for gravitational wave bursts from cosmic (super)strings
We report on a matched-filter search for gravitational wave bursts from
cosmic string cusps using LIGO data from the fourth science run (S4) which took
place in February and March 2005. No gravitational waves were detected in 14.9
days of data from times when all three LIGO detectors were operating. We
interpret the result in terms of a frequentist upper limit on the rate of
gravitational wave bursts and use the limits on the rate to constrain the
parameter space (string tension, reconnection probability, and loop sizes) of
cosmic string models.Comment: 11 pages, 3 figures. Replaced with version submitted to PR
Stacked Search for Gravitational Waves from the 2006 SGR 1900+14 Storm
We present the results of a LIGO search for short-duration gravitational
waves (GWs) associated with the 2006 March 29 SGR 1900+14 storm. A new search
method is used, "stacking'' the GW data around the times of individual
soft-gamma bursts in the storm to enhance sensitivity for models in which
multiple bursts are accompanied by GW emission. We assume that variation in the
time difference between burst electromagnetic emission and potential burst GW
emission is small relative to the GW signal duration, and we time-align GW
excess power time-frequency tilings containing individual burst triggers to
their corresponding electromagnetic emissions. We use two GW emission models in
our search: a fluence-weighted model and a flat (unweighted) model for the most
electromagnetically energetic bursts. We find no evidence of GWs associated
with either model. Model-dependent GW strain, isotropic GW emission energy
E_GW, and \gamma = E_GW / E_EM upper limits are estimated using a variety of
assumed waveforms. The stacking method allows us to set the most stringent
model-dependent limits on transient GW strain published to date. We find E_GW
upper limit estimates (at a nominal distance of 10 kpc) of between 2x10^45 erg
and 6x10^50 erg depending on waveform type. These limits are an order of
magnitude lower than upper limits published previously for this storm and
overlap with the range of electromagnetic energies emitted in SGR giant flares.Comment: 7 pages, 3 figure
Search for High Frequency Gravitational Wave Bursts in the First Calendar Year of LIGO's Fifth Science Run
We present an all-sky search for gravitational waves in the frequency range 1
to 6 kHz during the first calendar year of LIGO's fifth science run. This is
the first untriggered LIGO burst analysis to be conducted above 3 kHz. We
discuss the unique properties of interferometric data in this regime. 161.3
days of triple-coincident data were analyzed. No gravitational events above
threshold were observed and a frequentist upper limit of 5.4 events per year on
the rate of strong gravitational wave bursts was placed at a 90% confidence
level. Implications for specific theoretical models of gravitational wave
emission are also discussed.Comment: 13 pages, accepted for publication in Physical Review
Search for gravitational-wave bursts in the first year of the fifth LIGO science run
We present the results obtained from an all-sky search for gravitational-wave
(GW) bursts in the 64-2000 Hz frequency range in data collected by the LIGO
detectors during the first year (November 2005 - November 2006) of their fifth
science run. The total analyzed livetime was 268.6 days. Multiple hierarchical
data analysis methods were invoked in this search. The overall sensitivity
expressed in terms of the root-sum-square (rss) strain amplitude h_{rss} for
gravitational-wave bursts with various morphologies was in the range of 6 times
10^{-22} Hz^{-1/2} to a few times 10^{-21} Hz^{-1/2}. No GW signals were
observed and a frequentist upper limit of 3.6 events per year on the rate of
strong GW bursts was placed at the 90% confidence level. As in our previous
searches, we also combined this rate limit with the detection efficiency for
selected waveform morphologies to obtain event rate versus strength exclusion
curves. In sensitivity, these exclusion curves are the most stringent to date.Comment: v3: various figure and text edits; submitted to PRD; 26 page
Search for gravitational wave ringdowns from perturbed black holes in LIGO S4 data
According to general relativity a perturbed black hole will settle to a
stationary configuration by the emission of gravitational radiation. Such a
perturbation will occur, for example, in the coalescence of a black hole
binary, following their inspiral and subsequent merger. At late times the
waveform is a superposition of quasi-normal modes, which we refer to as the
ringdown. The dominant mode is expected to be the fundamental mode, l=m=2.
Since this is a well-known waveform, matched filtering can be implemented to
search for this signal using LIGO data. We present a search for gravitational
waves from black hole ringdowns in the fourth LIGO science run S4, during which
LIGO was sensitive to the dominant mode of perturbed black holes with masses in
the range of 10 Msun to 500 Msun, the regime of intermediate-mass black holes,
to distances up to 300 Mpc. We present a search for gravitational waves from
black hole ringdowns using data from S4. No gravitational wave candidates were
found; we place a 90%-confidence upper limit on the rate of ringdowns from
black holes with mass between 85 Msun and 390 Msun in the local universe,
assuming a uniform distribution of sources, of 3.2 x 10^{-5} yr^{-1} Mpc^{-3} =
1.6 x 10^{-3}yr^{-1} L_{10}^{-1}, where L_{10} is 10^{10} times the solar
blue-light luminosity.Comment: 8 pages, 6 figure
The present gravitational wave detection effort
Gravitational radiation offers a new non-electromagnetic window through which to observe the universe. The LIGO and Virgo Collaborations have completed a first joint data run with unprecedented sensitivities to gravitational waves. Results from searches in the data for a variety of astrophysical sources are presented. A second joint data run with improved detector sensitivities is underway, and soon major upgrades will be carried out to build Advanced LIGO and Advanced Virgo with expected improvements in event rates of more than 1000. In parallel there is a vigorous effort in the radio pulsar community to detect nHz gravitational waves via the timing residuals in an array of pulsars at different locations in the sky.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/85430/1/jpconf10_203_012002.pd
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
Multi-messenger observations of a binary neutron star merger
On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta
Localization and broadband follow-up of the gravitational-wave transient GW150914
A gravitational-wave (GW) transient was identified in data recorded by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) detectors on 2015 September 14. The event, initially designated G184098 and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimates of the time, significance, and sky location of the event were shared with 63 teams of observers covering radio, optical, near-infrared, X-ray, and gamma-ray wavelengths with ground- and space-based facilities. In this Letter we describe the low-latency analysis of the GW data and present the sky localization of the first observed compact binary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-ray Coordinates Network circulars, giving an overview of the participating facilities, the GW sky localization coverage, the timeline, and depth of the observations. As this event turned out to be a binary black hole merger, there is little expectation of a detectable electromagnetic (EM) signature. Nevertheless, this first broadband campaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broad capabilities of the transient astronomy community and the observing strategies that have been developed to pursue neutron star binary merger events. Detailed investigations of the EM data and results of the EM follow-up campaign are being disseminated in papers by the individual teams
Search for gravitational waves from low mass compact binary coalescence in 186 days of LIGO's fifth science run
We report on a search for gravitational waves from coalescing compact binaries, of total mass between 2 and 35M_☉, using LIGO observations between November 14, 2006 and May 18, 2007. No gravitational-wave signals were detected. We report upper limits on the rate of compact binary coalescence as a function of total mass. The LIGO cumulative 90%-confidence rate upper limits of the binary coalescence of neutron stars, black holes and black hole-neutron star systems are 1.4 × 10^(-2), 7.3 × 10(-4) and 3.6 × 10(-3) yr(-1) L_10^(-1), respectively, where L_(10_ is 10^(10) times the blue solar luminosit
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