black hole mergers

When Dead Stars Collide!

Gravity has been making waves - literally.  Earlier this month, the Nobel Prize in Physics was awarded for the first direct detection of gravitational waves two years ago. But astronomers just announced another huge advance in the field of gravitational waves - for the first time, we’ve observed light and gravitational waves from the same source.

There was a pair of orbiting neutron stars in a galaxy (called NGC 4993). Neutron stars are the crushed leftover cores of massive stars (stars more than 8 times the mass of our sun) that long ago exploded as supernovas. There are many such pairs of binaries in this galaxy, and in all the galaxies we can see, but something special was about to happen to this particular pair.

Each time these neutron stars orbited, they would lose a teeny bit of gravitational energy to gravitational waves. Gravitational waves are disturbances in space-time - the very fabric of the universe - that travel at the speed of light. The waves are emitted by any mass that is changing speed or direction, like this pair of orbiting neutron stars. However, the gravitational waves are very faint unless the neutron stars are very close and orbiting around each other very fast.

As luck would have it, the teeny energy loss caused the two neutron stars to get a teeny bit closer to each other and orbit a teeny bit faster.  After hundreds of millions of years, all those teeny bits added up, and the neutron stars were *very* close. So close that … BOOM! … they collided. And we witnessed it on Earth on August 17, 2017.  

Credit: National Science Foundation/LIGO/Sonoma State University/A. Simonnet

A couple of very cool things happened in that collision - and we expect they happen in all such neutron star collisions. Just before the neutron stars collided, the gravitational waves were strong enough and at just the right frequency that the National Science Foundation (NSF)’s Laser Interferometer Gravitational-Wave Observatory (LIGO) and European Gravitational Observatory’s Virgo could detect them. Just after the collision, those waves quickly faded out because there are no longer two things orbiting around each other!

LIGO is a ground-based detector waiting for gravitational waves to pass through its facilities on Earth. When it is active, it can detect them from almost anywhere in space.

The other thing that happened was what we call a gamma-ray burst. When they get very close, the neutron stars break apart and create a spectacular, but short, explosion. For a couple of seconds, our Fermi Gamma-ray Telescope saw gamma-rays from that explosion. Fermi’s Gamma-ray Burst Monitor is one of our eyes on the sky, looking out for such bursts of gamma-rays that scientists want to catch as soon as they’re happening.

And those gamma-rays came just 1.7 seconds after the gravitational wave signal. The galaxy this occurred in is 130 million light-years away, so the light and gravitational waves were traveling for 130 million years before we detected them.

After that initial burst of gamma-rays, the debris from the explosion continued to glow, fading as it expanded outward. Our Swift, HubbleChandra and Spitzer telescopes, along with a number of ground-based observers, were poised to look at this afterglow from the explosion in ultraviolet, optical, X-ray and infrared light. Such coordination between satellites is something that we’ve been doing with our international partners for decades, so we catch events like this one as quickly as possible and in as many wavelengths as possible.

Astronomers have thought that neutron star mergers were the cause of one type of gamma-ray burst - a short gamma-ray burst, like the one they observed on August 17. It wasn’t until we could combine the data from our satellites with the information from LIGO/Virgo that we could confirm this directly.

This event begins a new chapter in astronomy. For centuries, light was the only way we could learn about our universe. Now, we’ve opened up a whole new window into the study of neutron stars and black holes. This means we can see things we could not detect before.

The first LIGO detection was of a pair of merging black holes. Mergers like that may be happening as often as once a month across the universe, but they do not produce much light because there’s little to nothing left around the black hole to emit light. In that case, gravitational waves were the only way to detect the merger.

Image Credit: LIGO/Caltech/MIT/Sonoma State (Aurore Simonnet)

The neutron star merger, though, has plenty of material to emit light. By combining different kinds of light with gravitational waves, we are learning how matter behaves in the most extreme environments. We are learning more about how the gravitational wave information fits with what we already know from light - and in the process we’re solving some long-standing mysteries!

Want to know more? Get more information HERE.

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Gravitational Waves Win 2017 Nobel Prize In Physics, The Ultimate Fusion Of Theory And Experiment

“The 2017 Nobel Prize in Physics may have gone to three individuals who made an outstanding contribution to the scientific enterprise, but it’s a story about so much more than that. It’s about all the men and women over more than 100 years who’ve contributed, theoretically and experimentally and observationally, to our understanding of the precise workings of the Universe. Science is much more than a method; it’s the accumulated knowledge of the entire human enterprise, gathered and synthesized together for the betterment of everyone. While the most prestigious award has now gone to gravitational waves, the science of this phenomenon is only in its earliest stages. The best is yet to come.”

It’s official at long last: the 2017 Nobel Prize in Physics has been awarded to three individuals most responsible for the development and eventual direct detection of gravitational waves. Congratulations to Rainer Weiss, Kip Thorne, and Barry Barish, whose respective contributions to the experimental setup of gravitational wave detectors, theoretical predictions about which astrophysical events produce which signals, and the design-and-building of the modern LIGO interferometers helped make it all possible. The story of directly detecting gravitational waves is so much more, however, than the story of just these three individuals, or even than the story of their collaborators. Instead, it’s the ultimate culmination of a century of theoretical, experimental, and instrumentational work, dating back to Einstein himself. It’s a story that includes physics titans Howard Robertson, Richard Feynman, and Joseph Weber. It includes Russell Hulse and Joseph Taylor, who won a Nobel decades earlier for the indirect detection of gravitational waves. And it’s the story of over 1,000 men and women who contributed to LIGO and VIRGO, bringing us into the era of gravitational wave astronomy.

The 2017 Nobel Prize in Physics may only go to three individuals, but it’s the ultimate fusion of theory and experiment. And yes, the best is yet to come! 

An illustration of a newly detected black-hole merger, whose gravitational-wave signal suggests that at least one of the black holes was misaligned with its orbital motion before merging with its partner.

LIGO/Caltech/MIT/Sonoma State (Aurore Simonnet)

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Gravitational waves, Light and Merging neutron stars

Unlike black hole mergers (gif-1), when two neutron stars merge (gif-2) they give off a huge blast of light in addition to the gravitational wave.

Today LIGO announced that they were able to detect the gravitational waves from the merger of two neutron stars and the revolutionary thing about this is that with the help of telescopes situated across the globe we were to able to confirm this.

(Image credits: Left, Hubble/STScI; Right, 1M2H Team/UC Santa Cruz & Carnegie Observatories/Ryan Foley)

These are indeed truly exciting times and there is no denying. Have a great day!


* Watch this video to know more

**  How LIGO detects gravitational waves

Add GW170104 to the chart of black holes with known mass. The extremely energetic merger of two smaller black holes corresponds to the Laser Interferometer Gravitational-wave Observatory’s (LIGO) third detection of gravitational waves. The newfound black hole has a mass about 49 times that of the Sun, filling a gap between the masses of the two merged black holes detected previously by LIGO, with solar masses of 62 (GW150914) and 21 (GW151226). In all three cases, the signal in each of the twin LIGO detectors was unambiguously identified as coming from black hole mergers while a fourth case (LVT151012) resulted in a lower confidence detection. GW170104 is estimated to be some 3 billion light-years away, more distant than present estimates for GW150914 and GW151226. The ripples in spacetime were discovered during LIGO’s current observing run, which began November 30, 2016 and will continue through the summer. 

Illustration Credit: LIGO, NSF, Aurore Simonnet (Sonoma State U.)

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There is sound in space, thanks to gravitational waves

“These waves are maddeningly weak, and their effects on the objects in spacetime are stupendously tiny. But if you know how to listen for them — just as the components of a radio know how to listen for those long-frequency light waves — you can detect these signals and hear them just as you’d hear any other sound. With an amplitude and a frequency, they’re no different from any other wave.”

You’ve likely heard that there’s no sound in space; that sound needs a medium to travel through, and in the vacuum of space, there is none. That’s true… up to a point. If you were only a few light years away from a star, stellar remnant, black hole, or even a supernova, you’d have no way to hear, feel, or otherwise directly measure the pressure waves from those objects. But they emit another kind of wave that can be interpreted as sounds, if you listen correctly: gravitational waves. These waves are so powerful, that in the very first event we ever detected, the black hole-black hole merger we saw outshone, in terms of energy, all of the stars in the observable Universe combined. There really is sound in space, as long as you know how to listen for it properly.

Come learn about it, and catch a live event, live-blogged by me, this evening!

New simulations could help in hunt for massive mergers of neutron stars, black holes

Berkeley Lab scientists develop detailed models that provide new views of cataclysmic events in space

Now that scientists can detect the wiggly distortions in space-time created by the merger of massive black holes, they are setting their sights on the dynamics and aftermath of other cosmic duos that unify in catastrophic collisions.

Working with an international team, scientists at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) have developed new computer models to explore what happens when a black hole joins with a neutron star - the superdense remnant of an exploded star.
Using supercomputers to rip open neutron stars

The simulations, carried out in part at Berkeley Lab’s National Energy Research Scientific Computing Center (NERSC), are intended to help detectors home in on the gravitational-wave signals. Telescopes, too, can search for the brilliant bursts of gamma-rays and the glow of the radioactive matter that these exotic events can spew into surrounding space.

In separate papers published in a special edition of the scientific journal Classical and Quantum Gravity, Berkeley Lab and other researchers present the results of detailed simulations.

One of the studies models the first milliseconds (thousandths of a second) in the merger of a black hole and neutron star, and the other details separate simulations that model the formation of a disk of material formed within seconds of the merger, and of the evolution of matter that is ejected in the merger.

That ejected matter likely includes gold and platinum and a range of radioactive elements that are heavier than iron.

Any new information scientists can gather about how neutron stars rip apart in these mergers can help to unlock their secrets, as their inner structure and their likely role in seeding the universe with heavy elements are still shrouded in mystery.

“We are steadily adding more realistic physics to the simulations,” said - Foucart, who served as a lead author for one of the studies as a postdoctoral researcher in Berkeley Lab’s Nuclear Science Division.
“But we still don’t know what’s happening inside neutron stars. The complicated physics that we need to model make the simulations very computationally intensive.”

Finding signs of a black hole-neutron star merger

Foucart, who will soon be an assistant professor at the University of New Hampshire, added, “We are trying to move more toward actually making models of the gravitational-wave signals produced by these mergers,” which create a rippling in space-time that researchers hope can be detected with improvements in the sensitivity of experiments including Advanced LIGO, the Laser Interferometer Gravitational-Wave Observatory.

In February 2016, LIGO scientists confirmed the first detection of a gravitational wave, believed to be generated by the merger of two black holes, each with masses about 30 times larger than the sun.

The signals of a neutron star merging with black holes or another neutron star are expected to generate gravitational waves that are slightly weaker but similar to those of black hole-black hole mergers, Foucart said.

Radioactive ‘waste’ in space

Daniel Kasen, a scientist in the Nuclear Science Division at Berkeley Lab and associate professor of physics and astronomy at UC Berkeley who participated in the research, said that inside neutron stars “there may be exotic states of matter unlike anything realized anywhere else in the universe.”

In some computer simulations the neutron stars were swallowed whole by the black hole, while in others there was a fraction of matter coughed up into space. This ejected matter is estimated to range up to about one-tenth of the mass of the sun.

While much of the matter gets sucked into the larger black hole that forms from the merger, “the material that gets flung out eventually turns into a kind of radioactive 'waste,’” he said. “You can see the radioactive glow of that material for a period of days or weeks, from more than a hundred million light years away.” Scientists refer to this observable radioactive glow as a “kilonova.”

The simulations use different sets of calculations to help scientists visualize how matter escapes from these mergers. By modeling the speed, trajectory, amount and type of matter, and even the color of the light it gives off, astrophysicists can learn how to track down actual events.
The weird world of neutron stars

The size range of neutron stars is set by the ultimate limit on how densely matter can be compacted, and neutron stars are among the most superdense objects we know about in the universe.

Neutron stars have been observed to have masses up to at least two times that of our sun but measure only about 12 miles in diameter, on average, while our own sun has a diameter of about 865,000 miles. At large enough masses, perhaps about three times the mass of the sun, scientists expect that neutron stars must collapse to form black holes.

A cubic inch of matter from a neutron star is estimated to weigh up to 10 billion tons. As their name suggests, neutron stars are thought to be composed largely of the neutrally charged subatomic particles called neutrons, and some models expect them to contain long strands of matter - known as “nuclear pasta” - formed by atomic nuclei that bind together.

Neutron stars are also expected to be almost perfectly spherical, with a rigid and incredibly smooth crust and an ultrapowerful magnetic field. They can spin at a rate of about 43,000 revolutions per minute (RPMs), or about five times faster than a NASCAR race car engine’s RPMs.

The aftermath of neutron star mergers

The researchers’ simulations showed that the radioactive matter that first escapes the black hole mergers may be traveling at speeds of about 20,000 to 60,000 miles per second, or up to about one-third the speed of light, as it is swung away in a long “tidal tail.”

“This would be strange material that is loaded with neutrons,” Kasen said. “As that expanding material cools and decompresses, the particles may be able to combine to build up into the heaviest elements.” This latest research shows how scientists might find these bright bundles of heavy elements.

“If we can follow up LIGO detections with telescopes and catch a radioactive glow, we may finally witness the birthplace of the heaviest elements in the universe,” he said. “That would answer one of the longest-standing questions in astrophysics.”

Most of the matter in a black hole-neutron star merger is expected to be sucked up by the black hole within a millisecond of the merger, and other matter that is not flung away in the merger is likely to form an extremely dense, thin, donut-shaped halo of matter.

The thin, hot disk of matter that is bound by the black hole is expected to form within about 10 milliseconds of the merger, and to be concentrated within about 15 to 70 miles of it, the simulations showed. This first 10 milliseconds appears to be key in the long-term evolution of these disks.

Over timescales ranging from tens of milliseconds to several seconds, the hot disk spreads out and launches more matter into space. “A number of physical processes - from magnetic fields to particle interactions and nuclear reactions - combine in complex ways to drive the evolution of the disk,” said Rodrigo Fernández, an assistant professor of physics at the University of Alberta in Canada who led one of the studies.

Simulations carried out on NERSC’s Edison supercomputer were crucial in understanding how the disk ejects matter and in providing clues for how to observe this matter, said Fernández, a former UC Berkeley postdoctoral researcher.

What’s next?

Eventually, it may be possible for astronomers scanning the night sky to find the “needle in a haystack” of radioactive kilonovae from neutron star mergers that had been missed in the LIGO data, Kasen said.

“With improved models, we are better able to tell the observers exactly which flashes of light are the signals they are looking for,” he said. Kasen is also working to build increasingly sophisticated models of neutron star mergers and supernovae through his involvement in the DOE Exascale Computing Project.

As the sensitivity of gravitational-wave detectors improves, Foucart said, it may be possible to detect a continuous signal produced by even a tiny bump on the surface of a neutron star, for example, or signals from theorized one-dimensional objects known as cosmic strings.

“This could also allow us to observe events that we have not even imagined,” he said.

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LIGO-VIRGO Detects The First Three-Detector Gravitational Wave

“When you have a signal appearing in one detector, you can gain a rough estimate of its distance from you (with uncertainties), but with no information about its direction. A second detector not only gives another distance estimate, but the time difference between the two signals gives you some information about distance, allowing you to restrict yourself to an “arc” on the sky. But a third detector, with a third time difference, allows you to pinpoint a single point, albeit with significant uncertainties. This is where the word “triangulation” comes from, since you need three detectors to pinpoint a location-of-origin. That’s exactly what VIRGO was able to give.”

For over a century after the publication of General Relativity, it was uncertain whether gravitational waves were real or not. It wasn’t until their first direct detection less than two years ago, by the LIGO scientific collaboration, that their existence was spectacularly confirmed. With the VIRGO detector in Italy coming online this year to complement the twin LIGO detectors, however, so much more became possible. An actual position in space could be identified for the first time, enabling a possible correlation between the gravitational wave sky and the electromagnetic one. The three-dimensional polarization of a gravitational wave could be measured, and compared with the predictions of Einstein’s theory. And gravitational wave signals can be teased out earlier and measured to smaller amplitudes than ever before. Not only have we just seen our fourth gravitational wave event, we’ve seen it in all three detectors.

This discovery is, indeed, something big, but there’s even bigger science to come in the future! Come see what this first three-detector gravitational wave event has given us!

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Newest LIGO Signal Raises A Huge Question: Do Merging Black Holes Emit Light?

“The second merger held no such hints of electromagnetic signals, but that was less surprising: the black holes were of significantly lower mass, so any signal arising from them would be expected to be correspondingly lower in magnitude. But the third merger was large in mass again, more comparable to the first than the second. While Fermi has made no announcement, and Integral again reports a non-detection, there are two pieces of evidence that suggest there may have been an electromagnetic counterpart after all. The AGILE satellite from the Italian Space Agency detected a weak, short-lived event that occurred just half a second before the LIGO merger, while X-ray, radio and optical observations combined to identify a strange afterglow less than 24 hours after the merger.”

Whenever there’s a catastrophic, cataclysmic event in space, there’s almost always a tremendous release of energy that accompanies it. A supernova emits light; a neutron star merger emits gamma rays; a quasar emits radio waves; merging black holes emit gravitational waves. But if there’s any sort of matter present outside the event horizons of these black holes, they have the potential to emit electromagnetic radiation, or light signals, too. Our best models and simulations don’t predict much, but sometimes the Universe surprises us! With the third LIGO merger, there were two independent teams that claimed an electromagnetic counterpart within 24 hours of the gravitational wave signal. One was an afterglow in gamma rays and the optical, occurring about 19 hours after-the-fact, while the other was an X-ray burst occurring just half a second before the merger.

Could either of these be connected to these merging black holes? Or are we just grasping at straws here? We need more, better data to know for sure, but here’s what we’ve got so far!

LIGO detects gravitational waves for third time

The Laser Interferometer Gravitational-wave Observatory (LIGO) has made a third detection of gravitational waves, ripples in space and time, demonstrating that a new window in astronomy has been firmly opened. As was the case with the first two detections, the waves were generated when two black holes collided to form a larger black hole.

The newfound black hole, formed by the merger, has a mass about 49 times that of our sun. This fills in a gap between the masses of the two merged black holes detected previously by LIGO, with solar masses of 62 (first detection) and 21 (second detection).

Keep reading

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5 Facts We Can Learn If LIGO Detects Merging Neutron Stars

“We have already entered a new age in astronomy, where we’re not just using telescopes, but interferometers. We’re not just using light, but gravitational waves, to view and understand the Universe. If merging neutron stars reveal themselves to LIGO, even if the events are rare and the detection rate is low, it’s means we’ll have crossed that next frontier. The gravitational sky and the light-based sky will no longer be strangers to one another. Instead, we’ll be one step closer to understanding how the most extreme objects in the Universe actually work, and we’ll have a window into our cosmos that no human has ever had before.”

Two years ago, advanced LIGO turned on, and in that brief time, it’s already revealed a number of gravitational wave events. All of them, to no one’s surprise, have been merging black holes, since those are the easiest class of events for LIGO to detect. But beyond black holes, LIGO should also be sensitive to merging neutron stars. Even though the range over which LIGO can see them is much smaller, if there are enough neutron star-neutron star mergers happening, we might have a chance. A little over a week ago, a rumor broke that LIGO may have seen one, which would be a phenomenal occurrence. Not only would we have a new type of event that we detected in gravitational waves, we would, for the first time, have the capability of correlating the gravitational and electromagnetic skies. Astronomy, for the first time ever, could view the very same object in gravitational waves and through telescopes.

This is a big deal, and there are four more facts we’ll learn if LIGO sees it! Come find out what they are!

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RADIO-BURST DISCOVERY DEEPENS ASTROPHYSICS MYSTERY:
BRIEF PULSE DETECTED BY ARECIBO TELESCOPE
APPEARS TO COME FROM FAR BEYOND OUR GALAXY

The discovery of a split-second burst of radio waves by scientists using the Arecibo radio telescope in Puerto Rico provides important new evidence of mysterious pulses that appear to come from deep in outer space.

The finding by an international team of astronomers, published July 10 in The Astrophysical Journal, marks the first time that a so-called “fast radio burst” has been detected using an instrument other than the Parkes radio telescope in Australia. Scientists using the Parkes Observatory have recorded a handful of such events, but the lack of any similar findings by other facilities had led to speculation that the Australian instrument might have been picking up signals originating from sources on or near Earth.

“Our result is important because it eliminates any doubt that these radio bursts are truly of cosmic origin,” said Victoria Kaspi, an astrophysics professor at McGill University in Montreal and Principal Investigator for the pulsar-survey project that detected this fast radio burst. “The radio waves show every sign of having come from far outside our galaxy – a really exciting prospect.”

Exactly what may be causing such radio bursts represents a major new enigma for astrophysicists. Possibilities include a range of exotic astrophysical objects, such as evaporating black holes, mergers of neutron stars, or flares from magnetars – a type of neutron star with extremely powerful magnetic fields.

“Another possibility is that they are bursts much brighter than the giant pulses seen from some pulsars,” notes James Cordes, a professor of astronomy at Cornell University and co-author of the new study.

The unusual pulse was detected on Nov. 2, 2012, at the Arecibo Observatory, a National Science Foundation-sponsored facility that boasts the world’s largest and most sensitive radio telescope, with a radio-mirror dish spanning 305 meters and covering about 20 acres.

While fast radio bursts last just a few thousandths of a second and have rarely been detected, the international team of scientists reporting the Arecibo finding confirm previous estimates that these strange cosmic bursts occur roughly 10,000 times a day over the whole sky. This astonishingly large number is inferred by calculating how much sky was observed, and for how long, in order to make the few detections that have so far been reported.

“The brightness and duration of this event, and the inferred rate at which these bursts occur, are all consistent with the properties of the bursts previously detected by the Parkes telescope in Australia,” said Laura Spitler, lead author of the new paper. Dr. Spitler, now a postdoctoral researcher at the Max Planck Institute for Radio Astronomy in Bonn, Germany, was a PhD student at Cornell when the research work began.

The bursts appear to be coming from beyond the Milky Way galaxy based on measurement of an effect known as plasma dispersion. Pulses that travel through the cosmos are distinguished from man-made interference by the effect of interstellar electrons, which cause radio waves to travel more slowly at lower radio frequencies. The burst detected by the Arecibo telescope has three times the maximum dispersion measure that would be expected from a source within the galaxy, the scientists report.

The discovery was made as part of the Pulsar Arecibo L-Band Feed Array (PALFA) survey, which aims to find a large sample of pulsars and to discover rare objects useful for probing fundamental aspects of neutron star physics and testing theories of gravitational physics.

Efforts are now under way to detect radio bursts using radio telescopes that can observe broad swaths of the sky to help identify them. Telescopes under construction in Australia and South Africa as well as the CHIME telescope in Canada have the potential to detect fast radio bursts; astronomers say these and other new facilities could pave the way for many more discoveries and a better understanding of this mysterious cosmic phenomenon.

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Beyond Black Holes: Could LIGO Have Detected Merging Neutron Stars For The First Time?

“We are present at an incredible time in history: at the birth of the observational science of gravitational wave astronomy. The coming decades will reveal a series of “firsts,” and that should include the first binary neutron star merger, the first pinpointing of a gravitational wave source, and the first correlation between gravitational waves and an electromagnetic signal. If nature is kind to us, and the rumors are true, we may have just unlocked all three.”

It seems like an eternity ago, but it’s been under two years since LIGO first began the science run that would first detect merging black holes. Their latest scientific data run is scheduled to end in just two days, and thus far, they’ve announced a total of three black hole-black hole merger discoveries, along with a fourth probable candidate. Yet thanks to the Twitter account of renowned astrophysicist J. Craig Wheeler, a bit of information has leaked: LIGO may have discovered merging neutron stars for the first time. They’d be approximately ten times lighter than the black holes we’ve witnessed merging, which means the signals are only 10% as strong. In order to get the same amplitude, they’d need to be only 10% as distant, cutting the search volume down to 0.1% the volume. But still, neutron stars may be much more abundant, so we might have a chance. Just yesterday, Hubble observed a galaxy with a binary neutron star inside, just 130 million light years away.

Could we have just detected a merging neutron star pair for the first time, in both gravitational waves and electromagnetic radiation, together? The rush is on to find out!

New simulations could help in hunt for massive mergers of neutron stars, black holes

Now that scientists can detect the wiggly distortions in space-time created by the merger of massive black holes, they are setting their sights on the dynamics and aftermath of other cosmic duos that unify in catastrophic collisions.

Working with an international team, scientists at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) have developed new computer models to explore what happens when a black hole joins with a neutron star – the superdense remnant of an exploded star.

Keep reading

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The Nobel Doesn’t Mean Gravitational Wave Astronomy Is Over; It’s Just Getting Good

“We haven’t just detected gravitational waves directly, we’ve begun exploring in the era of gravitational wave astronomy. We aren’t just seeing the sky in a whole new way; we’re getting better and better at seeing it, and learning what we’re looking at. Because these events are transient, existing only for a short amount of time, we right now only get one opportunity to view these black hole-black hole mergers. But as time goes on and our detectors continue to improve, we’re going to continue to see the Universe as we never have before. The Nobel Prize may have been for already completed research, but the true fruits of gravitational wave astronomy are still out there amidst the great cosmic forest. Thanks to the groundwork laid by 100+ years of scientists, for the first time, it’s picking season.”

Yes, we detected gravitational waves, directly, for the first time! Just days after Advanced LIGO first turned on, a signal of a 36 solar mass black hole merging with a 29 solar mass black hole gave us our first robust, direct detection of these long-sought waves, changing astronomy forever. Einstein’s General Relativity was validated in a whole new way, and over 40 years of work on developing and building LIGO was vindicated at last. Now, it’s two years later, and yes, some of the most important team members have been awarded physics’ highest honor: the Nobel Prize. But gravitational wave astronomy isn’t over now; on the contrary, it’s only just beginning in earnest. With a third detector now online and two more coming along in the next few years, we’re not only poised to enter a new era in astronomy, we’re about to open up a whole new set of discoveries that would otherwise be impossible.

Here’s where we are, and here’s how we do it! Find out what advances are already underway since this Nobel-winning discovery was made!

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Astronomy’s ‘Rosetta Stone’: Merging Neutron Stars Seen With Both Gravitational Waves And Light

“For the first time in history, gravitational wave astronomy isn’t a pipe dream, nor is it a way of looking for esoteric objects we can’t see via any other means. Instead, it’s truly a part of our night sky, and the first signpost of an astronomical cataclysm. In the future, as gravitational wave astronomy improves, it may even serve as an early warning system, enabling us to locate sources about to merge before they ever do so. It may grow to include not only black holes and neutron stars, but white dwarfs and supermassive black holes swallowing objects as well. Gravitational wave astronomy is only two years old, and we haven’t even taken it to space yet. The next step in understanding the Universe is before us. Sit back and enjoy the ride!”

When the Advanced LIGO detectors turned on in 2015, it shook up the world when they detected their first event: the merger of two quite massive black holes. Since that time, they’ve observed black hole-black hole mergers multiple times, with the VIRGO detector in Italy joining them for the fourth event. But this wasn’t what LIGO/VIRGO expected to see; rather, they were built to hunt for merging neutron stars that were much closer by. Neutron star mergers would be superior to black hole mergers in an extraordinary way: it would enable other astronomers to get in on the action. Unlike black holes, merging neutron stars should emit radiation across the electromagnetic spectrum, from gamma-rays to UV/optical afterglows. On August 17th, LIGO and VIRGO saw their very first neutron star merger, pinpointing its location to galaxy NGC 4993, just 120 million light years away.

For the first time, we’ve joined the gravitational wave and light-based skies together with an incredible event. It’s a glorious step forward. And it’s just the beginning.

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Gravitational Waves: From Discovery Of The Year To Science Of The Century

“LIGO is back online and taking data right now at even greater sensitivity to 2015-2016. Among the things it hopes to see are:
*Increased statistics of the types of mergers already seen.
*Merging black holes of larger (up to 100) and smaller (down to 3 or 4) solar masses.
*Mismatched mergers, where two black holes of significantly different masses merge together.
*Neutron star mergers, where two collapsed objects left over from supernovae – but too small to form a black hole – spiral in and merge.
*Gravitational waves from “spike” events such as pulsar glitches, starquakes, and potentially even asymmetrical supernovae.
*And, hopefully, to correlate gravitational wave observations with electromagnetic ones, to find out which gravitational-wave producing events produce X-rays, Gamma rays, radio waves and light of any type!”

No doubt about it: the greatest science advance of 2016 was the end of the century-long wait for the first direct detection of gravitational waves. Not only were we able to detect the inspiral and merger of two black holes from their emission of gravitational waves, we were able to do it more than once. The announcement was a 101-year-after-the-fact confirmation of one of Einstein’s greatest and most unique predictions. But the real achievement isn’t simply that these detections happened, but what becomes possible. Gravitational wave astronomy is a science in its infancy, but is poised to become rich, varied and to open a whole new window on our understanding of the Universe. This isn’t just the discovery of the year, it’s a new type of science for the 21st century.

Don’t miss out on a moment of what’s possible, and don’t miss learning about why it’s so important to make this a reality!

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Ask Ethan: do gravitational waves exhibit wave-particle duality?

“We’ve actually got a few chances for this, although LIGO is unlikely to succeed at any of them. You see, quantum gravitational effects are strongest and most pronounced where you have strong gravitational fields in play at very tiny distances. How better to probe this than for merging black holes?! When two singularities merge together, these quantum effects — which should be departures from General Relativity — will show up at the moment of the merger, and just before (at the end of the inspiral) and just after (at the start of the ringdown) phases.”

Now that gravitational waves have been verified to exist, and the first black hole-black hole merger has been definitively detected by LIGO, it’s time to start thinking of the next steps in gravitational wave astronomy. The biggest one we can dream of, perhaps the holy grail of this field of study, is to go beyond General Relativity itself, and to find evidence that gravitation is a truly quantum theory at its core. If that’s true, then these gravitational waves should exhibit wave-particle duality, just like all the other quantum entities we know of. In this case, detecting the wave-like phenomenon, which took a century to do, was the easy part; detecting the particle nature of gravitons will be the hard part. Nevertheless, even though this is likely beyond the reach of LIGO, future missions will have a chance to see these quantum effects down the road.