Tag Archives: gravitational waves

Nobel Prize for Physics awarded to three LIGO scientists

The 2017 Nobel Prize for Physics has been awarded to three scientists involved in the development of the Laser Interferometer Gravitational-wave Observatory (LIGO), which detected the first gravitational waves in 2015.

While some of the recent Nobel Prizes have been absurd (such as the Peace award to Obama), this award is absolutely deserved and appropriate. Until LIGO detected that gravitational wave they were merely a theory. The detection proved the theory to be real.

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Gravitational waves from black hole collision detected

Three Earth gravitational wave observatories have detected the waves coming from the same collision of two black holes.

The collision was observed Aug. 14 at 10:30:43 a.m. Coordinated Universal Time (UTC) using the two National Science Foundation (NSF)-funded Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors located in Livingston, Louisiana, and Hanford, Washington, and the Virgo detector, funded by CNRS and INFN and located near Pisa, Italy.

The detection by the LIGO Scientific Collaboration (LSC) and the Virgo collaboration is the first confirmed gravitational wave signal recorded by the Virgo detector.

Based on the data obtained, they estimate that the two black holes 25 and 31 times the mass of the Sun and are about 1.8 billion light years away.

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LISA Pathfinder switched off

After a successful mission proving the technology for a full scale orbiting gravitational wave detector, LISA Pathfinder was shut off yesterday.

After 16 months of science measurements an international team deactivated the LISA Pathfinder satellite on the evening of the 18th of July 2017. The gravitational-wave laboratory in space powered down after receiving the last commands in the evening and circles the Sun on a safe parking orbit. LISA Pathfinder has tested key technologies for LISA, the future gravitational-wave observatory in space, and has demonstrated their operative readiness. LISA is scheduled to launch into space in 2034 as an ESA mission and will “listen” to the entire Universe by measuring low-frequency gravitational waves.

The idea is laudable, but for Europe to need another seventeen years to build and launch the full scale telescope is absurd. They now know what needs to be done. It should be relatively easy and quick to get it into orbit. And even if it isn’t easy, seventeen more years? Give me a break.

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Success of test mission paves way for orbiting gravitational wave detector

The success of LISA Pathfinder during the past year to test the technology for building an orbiting gravitational wave detector has now made it possible for Europe to approve construction of the full scale telescope, set to launch in the 2030s.

The LISA Pathfinder mission, launched in late 2015, beat its precision target by a factor of 1,000 and quieted critics who have doubted its potential, says project scientist Paul McNamara, an astrophysicist at ESA in Noordwijk, the Netherlands. “This is not the impossible task that some people believed it was.”

Currently set to fly in 2034, the full-scale Laser Interferometer Space Antenna (LISA) will be the space analogue of the Laser Interfero-meter Gravitational-Wave Observatory (LIGO), two machines in the United States — each with a pair of 4-kilometre-long arms — that first detected the ripples by ‘hearing’ the merger of two black holes. LISA’s three probes will fly in a triangle, millions of kilometres apart, making the mission sensitive to much longer gravitational waves, such as the ripples produced by the collisions of even larger black holes.

The article also notes that the European Space Agency also approved two other large missions, one to launch in 2022 and go the moons of Jupiter, another an X-ray observatory that will launch in 2028.

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Another gravity wave detected by LIGO

The LIGO gravitational wave detector has detected its second gravitational wave, thought to come from the merger of two black holes.

The new observation came at 3:38.53 Coordinated Universal Time on 26 December 2015—late on Christmas day at LIGO’s detectors in Livingston, Louisiana, and Hanford, Washington. As in the first event, the detectors sensed an oscillating stretching of space-time, the signal, according to Einstein’s 
general theory of relativity, of massive objects in violent motion. Computer modeling indicated that its source was two black holes spiraling together about 1.4 billion light-years away. (LIGO researchers had seen a weaker signal on 12 October 2015 that may be a third black hole merger.)

Note the last sentence in the quote above. They might have had a third detection, but are uncertain enough to have not claimed it as one.

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LISA Pathfinder proves space-based gravity wave detection technology

Engineers have announced that the gravity wave detection technology being tested in orbit by Europe’s LISA Pathfinder works.

To show that the necessary sensitivity is possible, LISA Pathfinder measures the distance between two masses, both of which are inside the spacecraft. “We’ve shrunk the arm of a large gravitational wave antenna to 35 centimeters so we could show it works properly,” Paul McNamara, LISA Pathfinder project scientist, told the press conference.

LISA Pathfinder was launched in December 2015 to a spot 1.5 million kilometers from Earth. When its test masses where first released to float free in February, “the relief was unbelievable,” McNamara says. Science operations began on 1 March and on that first day the team was able to measure distance variations between the masses much smaller than LISA Pathfinder’s mission requirements, Stefano Vitale, the mission’s principle investigator, told reporters. After a month, the variations were even smaller, “very close to [eLISA] requirements,” he says.

They now hope to launch an array of at least three such spacecraft by the mid-2030s.

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Want to discover gravitational waves? You can!

The citizen science project, Einstein@home, will begin providing its participants data from the upgraded LIGO gravitational wave detector beginning March 9.

Rather than looking for dramatic sources of gravitational waves, such as the black-hole merger that LIGO detected on 14 September, Einstein@home looks for quieter, slow-burn signals that might be emitted by fast-spinning objects such as some neutron stars. These remnants of supernova explosions are some of the least well understood objects in astrophysics: such searches could help to reveal their nature.

Because they produce a weaker signal than mergers, rotating sources require more computational power to detect. This makes them well-suited to a distributed search. “Einstein@home is used for the deepest searches, the ones that are computationally most demanding,” Papa says. The hope is to extract the weak signals from the background noise by observing for long stretches of time. “The beauty of a continuous signal is that the signal is always there,” she says.

To participate all you have to do is let their software become your screensaver, doing its work whenever you walk away from your computer.

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LISA Pathfinder cubes in freefall

After a week of testing scientists have now completely released LISA Pathfinder’s two gold-platinum cubes so that they are floating free within the spacecraft.

With the cubes released, the spacecraft is now measuring the position of each cube and using thrusters to adjust its position and keep the cubes floating within it. This success has essentially proven that the technology works, though they now have to see if the technology can be maintained in orbit for a long enough period of time to be worthwhile. If so, this mission will be followed by multiple similar spacecraft, flying in formation while also measuring their positions precisely relative to each other. If a gravitational wave rolls past, they will detect it by the tiny differences of each cube’s position, kind of like beach balls floating on the ocean as a wave rolls past.

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India okays its own LIGO detector

The Indian government today approved construction of LIGO-India, using some duplicate components already available from the American LIGO gravitational wave detector.

“We have built an exact copy of that instrument that can be used in the LIGO-India Observatory,” says David Shoemaker, leader of the Advanced LIGO Project and director of the MIT LIGO Lab, “ensuring that the new detector can both quickly come up to speed and match the U.S. detector performance.” LIGO will provide Indian researchers with the components and training to build and run the new Advanced LIGO detector, which will then be operated by the Indian team.

What this new instrument will accomplish is to give astronomers more information when a gravitational wave rolls past the Earth. By having detectors half a world apart, they will be able to better triangulate the direction the wave came from, which in turn will help astronomers eventually pinpoint its source event.

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LISA Pathfinder’s cubes floating free

More gravitational wave news: LISA Pathfinder’s two gold-platinum 46mm cubes have been released and are now floating free inside their spacecraft.

After a week of further testing, they will stop controlling the cube’s positions with electrostatic force. They will then watch them very precisely with lasers to test whether the equipment is capable of detecting distance shifts small enough for a future version, made up of three such spacecraft, to detect gravitational waves. The idea is that, as a wave rolls by, the cubes will shift positions at slightly different times, just as different beach balls will do so on ocean waves.

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First direct detection of a gravitational wave

The science team from the Laser Interferometer Gravitational-wave Observatory (LIGO) announced today that on September 14, 2015 they made the first direct detection of a gravitational wave, produced by the merging of two distant black holes.

Based on the observed signals, LIGO scientists estimate that the black holes for this event were about 29 and 36 times the mass of the sun, and the event took place 1.3 billion years ago. About three times the mass of the sun was converted into gravitational waves in a fraction of a second — with a peak power output about 50 times that of the whole visible universe. By looking at the time of arrival of the signals — the detector in Livingston recorded the event 7 milliseconds before the detector in Hanford — scientists can say that the source was located in the Southern Hemisphere.

According to general relativity, a pair of black holes orbiting around each other lose energy through the emission of gravitational waves, causing them to gradually approach each other over billions of years, and then much more quickly in the final minutes. During the final fraction of a second, the two black holes collide at nearly half the speed of light and form a single more massive black hole, converting a portion of the combined black holes’ mass to energy, according to Einstein’s formula E=mc2. This energy is emitted as a final strong burst of gravitational waves. These are the gravitational waves that LIGO observed.

Because of the faintness of the wave signal, I suspect that the scientists involved have spent the last four months reviewing their data and the instrument very carefully, to make sure this was not a false detection. That they feel confident enough to make this announcement tells us that they think the detection was real.

Recently ESA launched Lisa Pathfinder, a prototype space-based gravitational wave detector designed to test the technology for building a larger in-space observatory that would be far more sensitive that LIGO. Funding for that larger detector has dried up, Today’s announcement will likely help re-energize that funding effort.

More information here.

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The elusive effort to detect gravitational waves.

After spending more than half a billion dollars and eight years of looking without a single detection, the Laser Interferometer Gravitational-Wave Observatory (LIGO) has gotten a major upgrade.

If commissioning continues to go relatively smoothly, plans call for the first Advanced LIGO observing run to start in late 2015. A second run, with a decent shot of finding a gravitational wave, would occur in the winter of 2016–17. (Weiss likes to point out that a 2016 discovery would be a nice 100th-anniversary commemoration of Einstein’s paper describing gravitational waves.) By the third science run, planned for 2017–18, the machine should be getting sensitive enough to almost certainly nail a detection, says Reitze.

It is hoped that the increased sensitivity, ten times better than before. will allow LIGO to finally make the first detection of a gravitational wave.

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Astronomers think they have discovered a distant supermassive black hole that is being ejected from its galaxy at a speed of several million miles per hour.

Astronomers think they have discovered a distant supermassive black hole that is being ejected from its galaxy at a speed of several million miles per hour.

Although the ejection of a supermassive black hole from a galaxy by recoil because more gravitational waves are being emitted in one direction than another is likely to be rare, it nevertheless could mean that there are many giant black holes roaming undetected out in the vast spaces between galaxies. “These black holes would be invisible to us,” said co-author Laura Blecha, also of CfA, “because they have consumed all of the gas surrounding them after being thrown out of their home galaxy.”

This conclusion however is not final. The data could also be explained by the spiraling in of two supermassive black holes.

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