* Astronomy

Members Login
Post Info TOPIC: LIGO


L

Posts: 129189
Date:
RE: LIGO
Permalink  
 


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.

Read more

__________________


L

Posts: 129189
Date:
Permalink  
 

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.

Read more

__________________


L

Posts: 129189
Date:
Prototype gravitational-wave detector
Permalink  
 


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.

Read more

__________________


L

Posts: 129189
Date:
RE: LIGO
Permalink  
 


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.

Source

__________________


L

Posts: 129189
Date:
Permalink  
 

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.

Read more

__________________


L

Posts: 129189
Date:
Permalink  
 

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.

Read more (2590kb, PDF)

__________________


L

Posts: 129189
Date:
Permalink  
 



__________________


L

Posts: 129189
Date:
Permalink  
 

The Laser Interferometer Gravitational-Wave Observatory (LIGO) has reached its target detection sensitivity, but the goal of finding the elusive phenomena known as gravity waves remains as elusive as ever.

The two facilities, one in Hanford, Washington, and the other in Livingston, Louisiana, began a planned one-year continuous operation the fifth and longest duration so far last November. The instruments are able to resolve sudden distortions in space-time as small as 10-18 meter, or one-thousandth the diameter of a proton. But even such sensitivity is not sufficient to catch most cosmological events that could cause gravity waves.

"So far, there has been no direct detection" - Nergis Mavalvala, LIGO team member at MIT.

That should change with the installation of LIGO's next generation of instruments. Where the current configuration can detect only the "brightest" of events, such as the head-on collision of two super massive black holes, the Advanced LIGO package funding for which is scheduled to be added to the National Science Foundation's budget in fiscal year 2008 is expected to produce a tenfold improvement in sensitivity.

"The increased sensitivity is firmly set by the astrophysics that we know today" - Nergis Mavalvala.

The Advanced LIGO should improve the chances of gravity-wave detection by a factor of 1,000. This enhanced sensitivity will allow LIGO to detect the space-time implications of cosmic events such as the collisions of smaller black holes, or the absorption by black holes of neutron stars, events estimated to occur somewhere in the universe as often as once per day.
In particular, the team wants to observe a black-hole collision.

Read More

__________________
«First  <  1 2 | Page of 2  sorted by
 
Quick Reply

Please log in to post quick replies.



Create your own FREE Forum
Report Abuse
Powered by ActiveBoard