Tag: ligo

Neutron Star Smash-Up Produces Gravitational Waves And Light In Unprecedented Stellar Show​

The 2015 detection of gravitational waves – ripples in the very fabric of space and time – was one of the biggest scientific breakthroughs in a century.

But because it was caused by two black holes merging, the event was all but invisible, detectable indirectly via the LIGO facility.

Now a team of scientists has announced the fifth detection of gravitational waves, but there’s a groundbreaking difference this time around.

The ripples were caused by the collision of two neutron stars, meaning the event was accompanied by light, radio, and other electromagnetic signals for the first time.

First predicted by Albert Einstein over 100 years ago, gravitational waves are caused by cosmic cataclysms like the collision of two black holes, but because of the immense distance.

By the time they reach us here on Earth the distortions are occurring on the subatomic scale.

To observe waves that tiny, LIGO beams lasers down a 4-km (2.5-mi) long tunnel and measures how gravitational waves might warp the beam as they wash over our local corner of spacetime.

That delicate process is effective at confirming the phenomenon, but still somewhat indirect.

This is the first time that the collision of two neutron stars has been detected, and this is the closest and most precisely located gravitational wave signal we’ve received,” says Susan Scott, the Leader of the General Relativity Theory and Data Analysis Group at Australian National University (ANU), which played a key role in the observation.

It is also the loudest gravitational wave signal we’ve detected.

The collision occurred in a galaxy called NGC 4993, which lies about 130 million light-years away – that might sound far, but it’s much closer than previous observations, which occurred at distances of billions of light-years.

As well as producing gravitational waves, the neutron stars’ collision sent a host of electromagnetic signals sweeping across the universe, including a short gamma ray burst, X-rays, light and radio waves.

These were picked up by observatories all over the world, helping pinpoint the source.

ANU was among those, using SkyMapper and the Siding Spring Observatory in New South Wales, Australia, to observe the brightness and color of the light signals given off.

Along with learning more about gravitational waves, the discovery can teach astronomers about neutron stars.

Created when larger stars collapse, neutron stars are relatively tiny – only about 10 km (6.2 mi) wide – and incredibly dense, with very strong magnetic fields. Other than that, not a whole lot is known about them.

With this discovery we have the opportunity to learn so much more about neutron stars, which have been quite a mystery to us,” says Scott.

Unlike black holes, neutron star collisions emit other signals such as gamma rays, light and radio waves so astronomers around the world were able to observe the event through telescopes. This is an amazing time to be a scientist.

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Pass it on: New Scientist

Scientists Detect Gravitational Waves Caused By Two Black Holes Colliding 1.3 Billion Years Ago In Historic Experiment Proving The Theory Of General Relativity

Professor Stephen Hawking said the detection marked a moment in scientific history.

Gravitational waves provide a completely new way at looking at the universe,” he told the BBC. ‘The ability to detect them has the potential to revolutionize astronomy.

This discovery is the first detection of a black hole binary system and the first observation of black holes merging.

The gravitational wave found in this study is believed to be the product of a collision between two massive black holes, 1.3 billion light years away — a remarkably extreme event that has not been observed until now.

The colliding black holes that produced these gravitational waves created a violent storm in the fabric of space and time, a storm in which time speeded up, and slowed down, and sped up again, a storm in which the shape of space was bent in this way and that way,” Caltech physicist Kip Thorne said.

Based on the physics of this particular event, LIGO scientists estimate that the two black holes in this event were about 29 and 36 times the mass of the sun, and that 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. LIGO observed these gravitational waves.

The researchers detected the signal with two Laser Interferometer Gravitational-wave Observatories (LIGO) in Louisiana and Washington.

These are twin detectors carefully constructed to detect incredibly tiny vibrations from passing gravitational waves.

Once the researchers spotted a gravitational signal, they converted it into audio waves and listened to the sound of two black holes spiraling together, then merging into a larger single black hole.

We’re actually hearing them go thump in the night,” says Matthew Evans, an assistant professor of physics at MIT.

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 into each other at nearly one-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 radiation.

These waves then rippled through the universe, effectively warping the fabric of space-time, before passing through Earth more than a billion years later as faint traces of their former, violent origins.

This is the holy grail of science,” said Rochester Institute of Technology astrophysicist Carlos Lousto.

The last time anything like this happened was in 1888 when Heinrich Hertz detected the radio waves that had been predicted by James Clerk Maxwell’s field-equations of electromagnetism in 1865,” added Durham University physicist Tom McLeish.

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Gravitational Waves Just Led Us To The Incredible Origin Of Gold In The Universe

The Nobel Prize–winning Laser Interferometer Gravitational-Wave Observatory (LIGO) observatory has already changed the world of astronomy.

When the scientists in the LIGO collaboration announced the first detection of gravitational waves in 2016, it meant they’d discovered a new way to observe the universe.

For the first time, scientists could “listen” to ripples in spacetime created by the collision of massive objects like black holes.

But that was just the beginning. The dream, all along, was to combine gravitational wave detections with observations from more traditional telescopes.

On Monday, a team of thousands of LIGO scientists around the globe published an incredible finding spread throughout several papers in the journal Physical Review Letters.

Not only did these scientists detect, for the first time, the gravitational waves produced from two colliding neutron stars, but they were able to pinpoint their location in the sky and witness the event with optical and electromagnetic telescopes.

The gravitational waves tell physicists how large and how far away the objects are, and allow scientists to recreate the moments before they collided.

Then the observations in optical light and electromagnetic waves fill in the blanks that gravitational waves can’t answer.

They help astronomers nail down exactly what the objects were made out of, and which elements their collisions produced.

In this case, the scientists were able to conclude that the resulting explosion from a neutron star merger produces heavy elements like gold, platinum, and uranium.

On August 17 at 8:41 am, LIGO detected gravitational waves — literal distortions in space and time — passing through Earth.

LIGO is a pair of L-shaped observatories in Washington state and Louisiana that can detect when these waves temporarily squish and stretch the fabric of spacetime around us.

In the past two years, LIGO had detected gravitational waves generated by black holes that had crashed into one another.

When LIGO detects gravitational waves, it automatically sends out alerts to hundreds of scientists across the world. Brown was one of them.

We got on the phone very quickly, and we realized this was a very loud gravitational wave signal. It blew our socks off,” he says.

On the day of the gravitational wave detection, the scientists immediately got another clue that something big was happening.

Two seconds after LIGO detected the gravitational waves, Fermi, a NASA satellite, detected a gamma-ray burst, one of the most powerful explosions of energy we know of in the universe.

It had long been theorized that neutron star mergers could create gamma-ray bursts. This couldn’t be a coincidence.

But light from the neutron star merger and subsequent explosion would soon dim. And so the LIGO collaboration scientists were suddenly under intense pressure to move quickly.

The sooner you get telescopes on this thing, the more information you get,” Brown says.

Studying that light, and how it changes, would teach scientists a huge amount about neutron stars and how their collisions transform matter.

This discovery is so exciting because it means we’re truly in a new age of astronomy.

It means scientists can study celestial objects not just in terms of the light or radiation they emit they can also combine those observations with data from gravitational waves.

It means scientists have data on the entirety of this collision. They have data on how the two neutron stars danced around each other, they have data on the moment of impact, and they have extensive data on the aftermath.

Scientists expect to observe more black hole mergers, more neutron star mergers. But stranger, cooler observations may come through as well.

If LIGO and VIRGO continue to be upgraded, it’s possible they could detect gravitational waves still rippling away from the Big Bang.

Or, more excitingly, they could detect sources of gravitational waves that have never been predicted or observed.

I was a little sad I was not alive for the first moon landing,” Thomas Corbitt, a physicist and LIGO collaborator at Louisiana State University, says.

But when you see things like this, which are a testament to what people can do when they work together, it really is inspiring, and it teaches us about the universe.

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Pass it on: Popular Science

The Physics Nobel Goes To The Detection Of Ripples In Space And Time

The way the Nobel Committee tells it, the story of this year’s physics prize begins like a certain 1970s space opera.

Once upon a time, a long time ago, in a galaxy far, far away, two massive black holes engaged in a deadly dance,” said physicist and Nobel committee member Olga Botner at today’s prize announcement.

The pair spiraled toward each other, colliding to form an even bigger black hole with a mass 62 times that of Earth’s sun.

The impact shook the universe, generating ripples known as gravitational waves that warped the fabric of spacetime as they pulsed through.

By the time the collision’s reverberations reached Earth, they had quieted to a quiver.

Some 1.3 billion years after that ferocious black hole do-si-do, physicists at two observatories in the US simultaneously detected a ripple as a tiny compression and expansion in length in their machines.

This first detection of a gravitational wave took four decades of calculations, simulations, and engineering—and more than a billion dollars of US taxpayer money.

Today, physicists Rainer Weiss, Barry Barish, and Kip Thorne won the Nobel Prize in Physics for the pioneering work that led to this discovery.

They’ll split 9 million Swedish krona in prize money, or 1.1 million dollars; Weiss will receive half the prize while Barish and Thorne will split the other half.

Weiss and Thorne began to search for gravitational waves back in the ’70s, 50 years after Albert Einstein first predicted their existence in his theory of general relativity.

No one had seen a gravitational wave yet, so it was possible that Einstein had gotten some of his theory wrong.

Weiss, working at MIT, and Thorne, at Caltech, developed prototypes of a laser interferometer—a machine that could measure minuscule fluctuations in length.

Weiss brought the craftsmanship and engineering, while Thorne specialized in theoretical calculations.

Their designs led to machines that could detect compressions in spacetime thousands of times smaller than the width of a proton.

The descendants of those prototypes, one located in Louisiana and the other in Washington, detected the first gravitational wave in 2015.

But a sophisticated machine is only as clever as its operators. The Nobel Committee credits Barish, a physicist at Caltech, for assembling and managing the team—the Laser Interferometer Gravitational Wave Observatory collaboration—that made the discovery.

When Barish became LIGO’s leader in 1994, he expanded the group from about 40 researchers to more than a thousand people from all over the world.

He gathered experts specializing in black holes, gravity, lasers, statistics, vacuum systems, and everything else that goes into a giant, L-shaped observatory that can measure tiny contractions in its two 2.5-mile-long arms.

Since that first detection in 2015, LIGO has identified three other gravitational waves, also from black hole collisions. So far, all the measurements confirm Einstein’s theory of general relativity.

Now, physicists are trying to learn more details about these collisions and the black holes that produce them. This August, a similar observatory called VIRGO came online in Italy to collaborate with LIGO.

With VIRGO’s additional data, physicists will be able to more precisely locate where gravitational waves originate.

They want to find spacetime-warping effects from other types of collisions, such as ones between collapsed stars, known as neutron stars.

They want to observe tens of these per year and investigate their paths as they ripple toward Earth.

By studying how they move through space, physicists think they might be able to observe the waves interacting with new astronomical objects previously invisible to telescopes.

A hundred years after Einstein predicted their existence, the story of gravitational waves and their effects on the fabric of spacetime is only just beginning.

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Pass it on: Popular Science