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Post Info TOPIC: LIGO
Blobrana


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RE: LIGO
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LIGO observatory to offer tour, astronomy talk
New to the observatory is an Advanced LIGO Controls Prototype Quadruple Suspension, or in more simple terms, a roughly 1000 pound four-level steel pendulum. LIGO is located west of Richland on Highway 10.
There is no fee.
For more information call 372-8181 or e-mail outreach@ligo-wa.Caltech.edu.

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Blobrana


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Title: First LIGO search for gravitational wave bursts from cosmic (super)strings
Authors: LIGO Scientific Collaboration: B. Abbott, et al

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.

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Blobrana


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The Laser Interferometer Gravitational-Wave Observatory (LIGO) will be holding its free monthly tour from 1:30 to 4 p.m. May 9.

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Blobrana


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Astronomy boffins from two Australian universities are part of a revolutionary global effort to unlock the secrets of gravitational waves, which could provide a glimpse into the origins of the universe.
The University of Adelaide and the Australian National University (ANU) will take part in a $US200 million project to observe ripples in the curvature of space-time caused by gravity waves.
There is $2.4 million behind the Australian part of the project, in which Australian scientists will be responsible for building parts that will be used to assemble two advanced laser interferometer gravitational-wave observatories (LIGOs) in the United States.

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Blobrana


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The monthly tour of the Hanford Laser Interferometer Gravitational Wave Observatory, or LIGO, will be at 1:30 p.m. today.
Participants can learn about the observatory's work to detect gravitational waves hitting Earth from space. They will be able to see the control room and, via remote camera, the observatory's laser and vacuum equipment area.

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Blobrana


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Prototype gravitational-wave detector
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Physicists in the US and Australia have used the quantum nature of light to make an important step towards improving the sensitivity of kilometre-sized interferometers used to search for gravitational waves. By using light in a squeezed state they achieved a 44% improvement in sensitivity of a prototype gravitational-wave detector.
This figure could reach 300% in a full-scale detector and the team believes that squeezed-light sources could be tested in working detectors such as LIGO within 1-3 years. More sensitive detectors would be able to search larger volumes of the universe for sources of gravitational waves, making their detection more likely.

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Blobrana


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An analysis by the international LIGO (Laser Interferometer Gravitational-Wave Observatory) Scientific Collaboration has excluded one previously leading explanation for the origin of an intense gamma-ray burst that occurred last winter. Gamma-ray bursts are among the most violent and energetic events in the universe, and scientists have only recently begun to understand their origins.
On February 1, 2007, the Konus-Wind, Integral, Messenger, and Swift gamma-ray satellites measured a short but intense outburst of energetic gamma rays originating in the direction of M31, the Andromeda galaxy, located 2.5 million light-years away. The majority of such short (less than two seconds in duration) gamma-ray bursts (GRBs) are thought to emanate from the merger and coalescence of two massive but compact objects, such as neutron stars or black-hole systems. They can also come from astronomical objects known as soft gamma-ray repeaters, which are less common than binary coalescence events and emit less energetic gamma rays.
During the intense blast of gamma rays, known as GRB070201, the 4-km and 2-km gravitational-wave interferometers at the Hanford facility were in science mode and collecting data. They did not, however, measure any gravitational waves in the aftermath of the burst.

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Blobrana


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The race is on to detect ripples from the most massive events in the universe: spinning, orbiting, exploding or colliding ultra-dense objects like black holes and neutron stars.
In 1918, Albert Einstein predicted these cosmic events would radiate a propagating distortion of space and time: gravitational waves. After spending hundreds of millions of dollars to detect them, scientists have come up empty.

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Title: Searching for Gravitational Radiation from Binary Black Hole MACHOs in the Galactic Halo
Authors: Duncan A. Brown

The Laser Interferometer Gravitational Wave Observatory (LIGO) is one of a new generation of detectors of gravitational radiation. The existence of gravitational radiation was first predicted by Einstein in 1916, however gravitational waves have not yet been directly observed. One source of gravitation radiation is binary inspiral. Two compact bodies orbiting each other, such as a pair of black holes, lose energy to gravitational radiation. As the system loses energy the bodies spiral towards each other. This causes their orbital speed and the amount of gravitational radiation to increase, producing a characteristic ''chirp'' waveform in the LIGO sensitive band. In this thesis, matched filtering of LIGO science data is used to search for low mass binary systems in the halo of dark matter surrounding the Milky Way. Observations of gravitational microlensing events of stars in the Large Magellanic Cloud suggest that some fraction of the dark matter in the halo may be in the form of Massive Astrophysical Compact Halo Objects (MACHOs). It has been proposed that low mass black holes formed in the early universe may be a component of the MACHO population; some fraction of these black hole MACHOs will be in binary systems and detectable by LIGO. The inspiral from a MACHO binary composed of two 0.5 solar mass black holes enters the LIGO sensitive band around 40 Hz. The chirp signal increases in amplitude and frequency, sweeping through the sensitive band to 4400 Hz in 140 seconds. By using evidence from microlensing events and theoretical predictions of the population an upper limit is placed on the rate of black hole MACHO inspirals in the galactic halo.

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