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First climate change is backed up by the most extreme weather on record and now gravitational waves and black holes have been [HASHTAG]#confirmed[/HASHTAG] by direct observation
Bad month for Sisu
[HASHTAG]#ouch[/HASHTAG]
Bad month for Sisu
[HASHTAG]#ouch[/HASHTAG]
Climate and weather are not linked remember.
It was very cold in Finland this winter so logic points to global warming being a myth. As for Einstein, his work will be forgotten soon enough [HASHTAG]#youclimatards[/HASHTAG]
Gravity waves from black holes verify Einstein’s prediction
LIGO experiment reports first detection of spacetime vibrations, opening new window to the cosmos
BY
ANDREW GRANT
10:30AM, FEBRUARY 11, 2016
SWEET SUCCESS For the first time, physicists have directly observed gravitational waves, caused by two black holes colliding (illustrated here).
SXS
WASHINGTON — Tremors in the cosmic fabric of space and time have finally been detected, opening a new avenue for exploring the universe.
The historic discovery of those tremors, known as gravitational waves, comes almost exactly a century after Albert Einstein first posited their existence. Researchers with the Advanced Laser Interferometer Gravitational-Wave Observatory, or Advanced LIGO, announced the seminal detection February 11 at a news conference and in a paper in Physical Review Letters. The gravitational swell originated more than 750 million light-years away, where the high-speed dance of two converging black holes shook the very foundation upon which planets, stars and galaxies reside.
“It's the first time the universe has spoken to us through gravitational waves,” LIGO laboratory executive director David Reitze said at the news conference.
The discovery immediately becomes a likely candidate for a Nobel Prize, and not just because it ties a neat bow around decades of evidence supporting a major prediction of Einstein’s 1915 general theory of relativity. “Gravitational waves allow us to look at the universe not just with light but with gravity,” says Shane Larson, an astrophysicist at Northwestern University in Evanston, Ill. Gravitational waves can expose the gory details of black holes and other extreme phenomena that can’t be obtained with traditional telescopes. With this discovery, the era of gravitational wave astronomy has begun.
Gravitational waves from a collision between two black holes came from roughly 1.3 billion light-years away, most likely in the direction of the Magellanic clouds, two satellite galaxies of the Milky Way (smudges of light at bottom center). The colors represent different probabilities for where the signal originated.
LIGO
The detection occurred on September 14, 2015, four days before the official start of observations for the newly upgraded observatory. Striking gold so quickly raises hopes for an impending flurry of sightings.
The fleeting burst of waves arrived on Earth long after two black holes, one about 36 times the mass of the sun and the other roughly 29, spiraled toward each other and coalesced. If Isaac Newton had been right about gravity, then the mass of the two black holes would have exerted an invisible force that pulled the objects together. But general relativity maintains that those black holes merged because their mass indented the fabric of space and time (SN: 10/17/15, p. 16). As the black holes drew near in a deepening pit of spacetime, they also churned up that fabric, emitting gravitational radiation (or gravity waves, as scientists often call them). Unlike more familiar kinds of waves, these gravitational ripples don’t travel “through” space; they are vibrations of spacetime itself, propagating outward in all directions at the speed of light.
Nearly every instance of an object accelerating generates gravity waves — you produced feeble ones getting out of bed this morning. Advanced LIGO is fine-tuned to home in on more detectable (and scientifically relevant) fare: waves emitted from regions where a lot of mass is packed into small spaces and moving very quickly. These black holes certainly qualify. Their tremendous mass was packed into spheres about 150 kilometers in diameter. By the time the black holes experienced their final unifying plunge, they were circling each other at about half the speed of light. On September 14 at 4:50 a.m. Eastern time, the gravity waves emitted by the black holes during their last fractions of a second of independence encountered the two L-shaped LIGO detectors.
LIGO’s detectors in Hanford, Wash., and Livingston, La., newly reactivated after five years of upgrades, each consist of a powerful laser that splits into two perpendicular, 4-kilometer-long beams. When the gravitational waters of spacetime are calm, the beams recombine at the junction and cancel each other out — the troughs of one beam’s 1,064-nanometer waves of laser light completely negate the crests of the second beam’s waves.
The two LIGO detectors registered nearly identical signals (top and middle) almost simultaneously as gravitational waves from a black hole collision passed by the Earth. The measured signals also closely match with predictions of what such a signal should look like.
LIGO
But the gravitational disturbance from the black hole pair distorted spacetime, slightly squeezing one arm of the detector while stretching the other (SN: 1/8/00, p. 26).When the beams recombined, the light no longer matched up perfectly. The detectors sensed that crest missed trough by the tiniest of distances, about a thousandth the diameter of a proton.
The LIGO facilities registered the signal just 7 milliseconds apart, indicating a light-speed pulse from deep space rather than a slower-moving vibration from an underground quake or a big rig rumbling along the highway. Physicists used the combined measurements to estimate a distance of 750 million to 1.8 billion light-years to the black holes. At least one more detector, preferably two, would be needed to triangulate the precise location of the black holes in the sky.
While the rendezvous was millions of years in the making, only the final two-tenths of a second produced gravity waves with the requisite intensity and frequency for detection by Advanced LIGO. Those two-tenths of a second told quite a story. At first, the black holes were circling each other about 17 times a second; by the end, it was 75. The gravity wave frequency and intensity reached a peak, and then the black holes merged. The show was over.
Combining the wave measurements with computer simulations, the scientists determined that a pair of 36- and 29-solar-mass black holes had become one 62-solar-mass beast. The missing three suns’ worth of mass had been transformed into energy (Einstein again, E=mc2) and carried away in the form of gravity waves. The power output during that mass-energy conversion exceeded that of all the stars in the universe combined.
The observed signal matches what physicists expected from a black hole merger almost perfectly. Ingrid Stairs, an astrophysicist at the University of British Columbia not involved with LIGO, says she and her colleagues were “bowled over by how beautiful it was.” Translated into sound, the signal resembled a rumbling followed by a chirp. “It stood out like a sore thumb,” says Rainer Weiss, one of the primary architects of LIGO. “We didn’t expect anything this big.” Weiss had visited Livingston just days before and almost shut down the detector to fix some minor problems. Had he done so, “we would have missed it.”
Despite the seeming no-doubt signal, LIGO researchers conducted a series of rigorous statistical tests. The signal survived. “I have great confidence in the team as a whole and everything they’ve done with the data,” Stairs says.
LIGO’s announcement falls between two very relevant centennials: Einstein’s introduction of general relativity (November 1915) and his prediction of gravitational waves (June 1916, though he had to fix the math two years later). Russell Hulse and Joseph Taylor Jr. won the 1993 Nobel Prize in physics for deducing gravity wave emission based on the motion of a stellar corpse called a neutron star and a closely orbiting companion. Now Advanced LIGO has sealed the deal with the first direct measurement.
The observatory achieved what its predecessor, which ran from 2001 to 2010, could not because of a five-year upgrade that enhanced sensitivity by at least a factor of three. Increased sensitivity translates to identifying more distant objects: If the search area of first-generation LIGO included all the space that could fit within a baseball, Advanced LIGO could spot everything inside a basketball. The comparison to everyday-sized objects ends there. Advanced LIGO’s range extends up to 5 billion light-years in all directions for merging objects about 100 times the mass of the sun, project leader David Shoemaker of MIT says. That extended reach, plus an extra boost in sensitivity at the wave frequencies associated with black holes, enabled the historic detection.
This ability to examine black holes and other influential dark objects without actually “seeing” them with light has scientists excited about the gravitational wave era. Black holes gobble up some matter and launch the rest away in powerful jets, scattering atoms within and between galaxies; pairs of neutron stars, also targets of Advanced LIGO, may ultimately trigger gamma-ray bursts, among the brightest and most energetic explosions known in the universe.
Yet while the influence of these cosmic troublemakers is sometimes visible with traditional telescopes, the objects themselves are not. Gravity waves offer a direct probe, and as a bonus they don’t get impeded by gas, dust and other cosmic absorbers as light does. “It opens up a new window into astronomy that we never had,” says John Mather, a Nobel-winning astrophysicist in attendance at the news conference. Before this discovery, scientists had never observed a pair of black holes orbiting each other. A big next step, scientists say, is to observe a nearby supernova or the collision of neutron stars via both gravity waves and light.
Gravitational wave astronomy has begun with the Advanced LIGO detection, but there’s lots more to come. LIGO scientists still have three months of data to sort through from their first round of observing, and the analysis of the signal suggests similar events should occur multiple times a year. At the same time, the researchers are upgrading the detectors so that they can spot neutron star and black hole collisions even farther away. The observatory should be back up and running by late summer, says LIGO chief detector scientist Peter Fritschel.
Later this year, European partners of the LIGO collaboration plan to restart their revamped gravity wave observatory, Advanced Virgo, near Pisa, Italy, providing a crucial third ultrasensitive detector for pinpointing gravity wave sources. Similar detectors are in the works for Japan and India.
Researchers designed LIGO to spot waves in the sweet spot for converging black holes and neutron stars, with a frequency ranging from tens of hertz to several thousand. But just as scientists use radio and gamma-ray telescopes to probe different frequencies of light, physicists are building detectors sensitive to a range of gravity wave frequencies. The eLISA mission, a space observatory consisting of three miniature satellites, will hunt for waves with frequencies under 1 hertz when it launches in the 2030s. The satellite trio should be able to resolve black holes from the early universe as well as hefty ones millions of times the mass of the sun. On January 22, a satellite designed to test eLISA technology settled into orbit around the sun about 1.5 million kilometers away. “We have detection techniques at various frequencies that are all becoming viable at roughly the same time,” Northwestern’s Larson says.
The LIGO result is not relevant to the 2014 claim of a gravity wave sighting, since rescinded, by scientists with the BICEP2 telescope near the South Pole (SN: 2/21/15, p. 13). BICEP2 and similar telescopes hunt for gravity waves with a much lower frequency, signaling reverberations from a split-second span just after the Big Bang called inflation, when space itself stretched rapidly. Though not detectable directly, these inflation-era gravity waves should be encoded in the universe’s earliest light, the cosmic microwave background.
Scientists may well detect those flavors of gravitational waves very soon. But for now, they can bask in a discovery 100 years in the making. “This was truly a scientific moonshot,” Reitze said. “We did it. We landed on the moon.”
Massive news. Sis????
LIGO experiment reports first detection of spacetime vibrations, opening new window to the cosmos
BY
ANDREW GRANT
10:30AM, FEBRUARY 11, 2016
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SWEET SUCCESS For the first time, physicists have directly observed gravitational waves, caused by two black holes colliding (illustrated here).
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WASHINGTON — Tremors in the cosmic fabric of space and time have finally been detected, opening a new avenue for exploring the universe.
The historic discovery of those tremors, known as gravitational waves, comes almost exactly a century after Albert Einstein first posited their existence. Researchers with the Advanced Laser Interferometer Gravitational-Wave Observatory, or Advanced LIGO, announced the seminal detection February 11 at a news conference and in a paper in Physical Review Letters. The gravitational swell originated more than 750 million light-years away, where the high-speed dance of two converging black holes shook the very foundation upon which planets, stars and galaxies reside.
“It's the first time the universe has spoken to us through gravitational waves,” LIGO laboratory executive director David Reitze said at the news conference.
The discovery immediately becomes a likely candidate for a Nobel Prize, and not just because it ties a neat bow around decades of evidence supporting a major prediction of Einstein’s 1915 general theory of relativity. “Gravitational waves allow us to look at the universe not just with light but with gravity,” says Shane Larson, an astrophysicist at Northwestern University in Evanston, Ill. Gravitational waves can expose the gory details of black holes and other extreme phenomena that can’t be obtained with traditional telescopes. With this discovery, the era of gravitational wave astronomy has begun.
You must log in or register to see images
Gravitational waves from a collision between two black holes came from roughly 1.3 billion light-years away, most likely in the direction of the Magellanic clouds, two satellite galaxies of the Milky Way (smudges of light at bottom center). The colors represent different probabilities for where the signal originated.
LIGO
The detection occurred on September 14, 2015, four days before the official start of observations for the newly upgraded observatory. Striking gold so quickly raises hopes for an impending flurry of sightings.
The fleeting burst of waves arrived on Earth long after two black holes, one about 36 times the mass of the sun and the other roughly 29, spiraled toward each other and coalesced. If Isaac Newton had been right about gravity, then the mass of the two black holes would have exerted an invisible force that pulled the objects together. But general relativity maintains that those black holes merged because their mass indented the fabric of space and time (SN: 10/17/15, p. 16). As the black holes drew near in a deepening pit of spacetime, they also churned up that fabric, emitting gravitational radiation (or gravity waves, as scientists often call them). Unlike more familiar kinds of waves, these gravitational ripples don’t travel “through” space; they are vibrations of spacetime itself, propagating outward in all directions at the speed of light.
Nearly every instance of an object accelerating generates gravity waves — you produced feeble ones getting out of bed this morning. Advanced LIGO is fine-tuned to home in on more detectable (and scientifically relevant) fare: waves emitted from regions where a lot of mass is packed into small spaces and moving very quickly. These black holes certainly qualify. Their tremendous mass was packed into spheres about 150 kilometers in diameter. By the time the black holes experienced their final unifying plunge, they were circling each other at about half the speed of light. On September 14 at 4:50 a.m. Eastern time, the gravity waves emitted by the black holes during their last fractions of a second of independence encountered the two L-shaped LIGO detectors.
LIGO’s detectors in Hanford, Wash., and Livingston, La., newly reactivated after five years of upgrades, each consist of a powerful laser that splits into two perpendicular, 4-kilometer-long beams. When the gravitational waters of spacetime are calm, the beams recombine at the junction and cancel each other out — the troughs of one beam’s 1,064-nanometer waves of laser light completely negate the crests of the second beam’s waves.
You must log in or register to see images
The two LIGO detectors registered nearly identical signals (top and middle) almost simultaneously as gravitational waves from a black hole collision passed by the Earth. The measured signals also closely match with predictions of what such a signal should look like.
LIGO
But the gravitational disturbance from the black hole pair distorted spacetime, slightly squeezing one arm of the detector while stretching the other (SN: 1/8/00, p. 26).When the beams recombined, the light no longer matched up perfectly. The detectors sensed that crest missed trough by the tiniest of distances, about a thousandth the diameter of a proton.
The LIGO facilities registered the signal just 7 milliseconds apart, indicating a light-speed pulse from deep space rather than a slower-moving vibration from an underground quake or a big rig rumbling along the highway. Physicists used the combined measurements to estimate a distance of 750 million to 1.8 billion light-years to the black holes. At least one more detector, preferably two, would be needed to triangulate the precise location of the black holes in the sky.
While the rendezvous was millions of years in the making, only the final two-tenths of a second produced gravity waves with the requisite intensity and frequency for detection by Advanced LIGO. Those two-tenths of a second told quite a story. At first, the black holes were circling each other about 17 times a second; by the end, it was 75. The gravity wave frequency and intensity reached a peak, and then the black holes merged. The show was over.
Combining the wave measurements with computer simulations, the scientists determined that a pair of 36- and 29-solar-mass black holes had become one 62-solar-mass beast. The missing three suns’ worth of mass had been transformed into energy (Einstein again, E=mc2) and carried away in the form of gravity waves. The power output during that mass-energy conversion exceeded that of all the stars in the universe combined.
The observed signal matches what physicists expected from a black hole merger almost perfectly. Ingrid Stairs, an astrophysicist at the University of British Columbia not involved with LIGO, says she and her colleagues were “bowled over by how beautiful it was.” Translated into sound, the signal resembled a rumbling followed by a chirp. “It stood out like a sore thumb,” says Rainer Weiss, one of the primary architects of LIGO. “We didn’t expect anything this big.” Weiss had visited Livingston just days before and almost shut down the detector to fix some minor problems. Had he done so, “we would have missed it.”
Despite the seeming no-doubt signal, LIGO researchers conducted a series of rigorous statistical tests. The signal survived. “I have great confidence in the team as a whole and everything they’ve done with the data,” Stairs says.
LIGO’s announcement falls between two very relevant centennials: Einstein’s introduction of general relativity (November 1915) and his prediction of gravitational waves (June 1916, though he had to fix the math two years later). Russell Hulse and Joseph Taylor Jr. won the 1993 Nobel Prize in physics for deducing gravity wave emission based on the motion of a stellar corpse called a neutron star and a closely orbiting companion. Now Advanced LIGO has sealed the deal with the first direct measurement.
The observatory achieved what its predecessor, which ran from 2001 to 2010, could not because of a five-year upgrade that enhanced sensitivity by at least a factor of three. Increased sensitivity translates to identifying more distant objects: If the search area of first-generation LIGO included all the space that could fit within a baseball, Advanced LIGO could spot everything inside a basketball. The comparison to everyday-sized objects ends there. Advanced LIGO’s range extends up to 5 billion light-years in all directions for merging objects about 100 times the mass of the sun, project leader David Shoemaker of MIT says. That extended reach, plus an extra boost in sensitivity at the wave frequencies associated with black holes, enabled the historic detection.
This ability to examine black holes and other influential dark objects without actually “seeing” them with light has scientists excited about the gravitational wave era. Black holes gobble up some matter and launch the rest away in powerful jets, scattering atoms within and between galaxies; pairs of neutron stars, also targets of Advanced LIGO, may ultimately trigger gamma-ray bursts, among the brightest and most energetic explosions known in the universe.
Yet while the influence of these cosmic troublemakers is sometimes visible with traditional telescopes, the objects themselves are not. Gravity waves offer a direct probe, and as a bonus they don’t get impeded by gas, dust and other cosmic absorbers as light does. “It opens up a new window into astronomy that we never had,” says John Mather, a Nobel-winning astrophysicist in attendance at the news conference. Before this discovery, scientists had never observed a pair of black holes orbiting each other. A big next step, scientists say, is to observe a nearby supernova or the collision of neutron stars via both gravity waves and light.
Gravitational wave astronomy has begun with the Advanced LIGO detection, but there’s lots more to come. LIGO scientists still have three months of data to sort through from their first round of observing, and the analysis of the signal suggests similar events should occur multiple times a year. At the same time, the researchers are upgrading the detectors so that they can spot neutron star and black hole collisions even farther away. The observatory should be back up and running by late summer, says LIGO chief detector scientist Peter Fritschel.
Later this year, European partners of the LIGO collaboration plan to restart their revamped gravity wave observatory, Advanced Virgo, near Pisa, Italy, providing a crucial third ultrasensitive detector for pinpointing gravity wave sources. Similar detectors are in the works for Japan and India.
Researchers designed LIGO to spot waves in the sweet spot for converging black holes and neutron stars, with a frequency ranging from tens of hertz to several thousand. But just as scientists use radio and gamma-ray telescopes to probe different frequencies of light, physicists are building detectors sensitive to a range of gravity wave frequencies. The eLISA mission, a space observatory consisting of three miniature satellites, will hunt for waves with frequencies under 1 hertz when it launches in the 2030s. The satellite trio should be able to resolve black holes from the early universe as well as hefty ones millions of times the mass of the sun. On January 22, a satellite designed to test eLISA technology settled into orbit around the sun about 1.5 million kilometers away. “We have detection techniques at various frequencies that are all becoming viable at roughly the same time,” Northwestern’s Larson says.
The LIGO result is not relevant to the 2014 claim of a gravity wave sighting, since rescinded, by scientists with the BICEP2 telescope near the South Pole (SN: 2/21/15, p. 13). BICEP2 and similar telescopes hunt for gravity waves with a much lower frequency, signaling reverberations from a split-second span just after the Big Bang called inflation, when space itself stretched rapidly. Though not detectable directly, these inflation-era gravity waves should be encoded in the universe’s earliest light, the cosmic microwave background.
Scientists may well detect those flavors of gravitational waves very soon. But for now, they can bask in a discovery 100 years in the making. “This was truly a scientific moonshot,” Reitze said. “We did it. We landed on the moon.”
Massive news. Sis????
Not having that, not with the scientific communities willingness to 'adjust' data. Next they will be saying they are going back to the moon
I am a bit confused about the whole "gravity wave" thing, I understand how we have proved the existence but am unsure how it will help us study the universe as is being claimed.
I watched an interview with a woman from the team that proved the existence and she said they were just lucky enough to have been monitoring when the wave passed through.
How do they know when or where it was created and how will it make study of the universe any better if we just have to be "lucky" to monitor at the right time?
I watched an interview with a woman from the team that proved the existence and she said they were just lucky enough to have been monitoring when the wave passed through.
How do they know when or where it was created and how will it make study of the universe any better if we just have to be "lucky" to monitor at the right time?
its lucky there is nobody around whose likely to pronounce that you are too stupid to even understand and so thereby not worthy of an answer. Either way its all hocus pocus to me.
Where's Sis to refute the claims that this ratifies general relativity and black holes? Typical
Read this:
Black hole heavyweights triggered gravity wave event
LIGO team expects more detections later this year
BY
CHRISTOPHER CROCKETT
12:34PM, FEBRUARY 17, 2016
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MAKING WAVES In the wake of a black hole collision, one bigger black hole (middle) is left behind as gravitational waves (blue and purple bands) ripple away, as seen in this still from a computer simulation. The colors near the black hole illustrate how gravity slows time (clocks would tick slower in the orange zone).
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The recent detection of gravitational waves is a stunning confirmation of Albert Einstein’s theories and the start of a new way of observing the universe. And at the center of it all is a celebrity couple: the first known pairing of black holes and the most massive ones found outside of the cores of galaxies.
On September 14, the Advanced Laser Interferometer Gravitational-Wave Observatory, or LIGO, sensed a disturbance in spacetime caused by two massive black holes smashing together (SN Online: 2/11/16). “It’s quite an incredible discovery,” says Vikram Ravi, an astrophysicist at Caltech. “They've seen objects that I guess none of us outside the collaboration imagined they might see.” Withmasses of 29 and 36 suns, these black holes were roughly twice as massive as the previous record holders.
Those masses actually aren’t too shocking, says Jeffrey McClintock, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. Very massive stars, though rare, should give rise to very massive black holes. What would have been more surprising, he says, is if LIGO failed to turn up any black holes this large. “If the nearest 1,000 stars had been investigated and we hadn’t found any planets, I would go back to church,” he says. “I feel the same way about two 30-solar-mass black holes.”
There are heavier black holes. Those monsters live in the centers of galaxies and can weigh billions of times as much as the sun. But they are different beasts entirely, probably built up as galaxies collide. Black holes such as those detected by LIGO are born when a massive star dies. And given their masses, “they likely formed in a fairly different environment than the Milky Way,” Ravi says.
How much mass a star ends up with at the end of its life depends partly on its store of elements heavier than helium. Atoms such as carbon, magnesium and iron present larger targets to the light that’s escaping a star. As light races outward, it bumps into these atoms, which in turn shove the surrounding gas along. The heavy elements behave like little snowplows attached to the photons, whittling away at the star’s mass as the light radiates into space. To make black holes as massive as LIGO’s, the original stars must have had fewer of these heavy elements than typical stars in our neighborhood, the LIGO team reports February 11 in the Astrophysical Journal Letters.
One possibility is that the stars formed early in the universe before heavy elements had a chance to accumulate. At the other extreme, the stars could have formed more recently in a relatively nearby (or local) and pristine pocket such as a dwarf galaxy. “With one observation, it’s impossible to say if it’s on one side of the continuum or the other,” says Vicky Kalogera, a LIGO astrophysicist at Northwestern University in Evanston, Ill.
The best estimates put the collision in a galaxy about 1.3 billion light-years away (give or take a few hundred million light-years) in the southern sky, roughly in the direction of the Magellanic Clouds, two satellites of the Milky Way. A third LIGO facility, such as one proposed for India, will help narrow down precise positions of future detections. So would a simultaneous burst of electromagnetic radiation from the location of a collision. LIGO has agreements with telescopes around the world (and in space) to keep an eye out for any flashes of light that occur at the same time as a gravity wave detection. For LIGO’s debut, no observatories reported anything definitive. But the Fermi gamma-ray satellite did see something interesting, astrophysicist Valerie Connaughton and colleagues report online February 14 at arXiv.org.
“We found a little blip that’s weaker than anything we’d normally look at,” says Connaughton, of the Universities Space Research Association in Huntsville, Ala. At 0.4 seconds after LIGO’s detection, Fermi recorded a very faint flash of gamma rays. “We’d normally never pick it out of the data,” she says. Researchers can’t pinpoint precisely where the burst came from, but the direction is roughly consistent with LIGO’s.
If the black hole collision did blast out gamma rays, theorists are going to have some explaining to do. Merging black holes shouldn’t release any electromagnetic radiation. It’s only when neutron stars get involved that telescopes should see flashes of light. During a recent phone call with colleagues about the Fermi data, “the theorists were already arguing with each other,” Connaughton says.
But before the theorists get too worked up, researchers need to figure out if what Fermi saw had anything to do with LIGO’s black holes. “We’re definitely not saying we saw an [electromagnetic] counterpart,” says Connaughton. It could be just a coincidence. During nearly 67 hours of observing in September, Fermi saw 27 similar gamma ray bursts. The only way to be certain is to wait for more LIGO detections. “If it’s real, it’s not going to be a one-off,” she says.
LIGO’s debut detection appeared during a test run in September; researchers are currently analyzing LIGO data accumulated during the four months that followed, and another science run is planned for later this year. The team is optimistic about their chances of finding more events. LIGO could have sensed a collision between two 30-solar-mass black holes out to about 6 billion light-years away. Given that researchers found one (so far) in 16 days of data, and assuming that’s a typical couple of weeks in the universe, then researchers estimate thatbetween two and 53 similar collisions occur per cubic gigaparsec per year. (One cubic gigaparsec is a volume of space roughly 4 billion light-years across.)
If those estimates are correct, scientists think LIGO could have detected up to about 10 more similar collisions in its first four months of operation, and possibly hundreds once the facility is running at full sensitivity. And that’s not including collisions of black holes with different masses, smashups of neutron stars or any other cosmic calamities that could rattle spacetime.
As more collisions are found, astronomers should get a better handle on where binary black holes form. “We may find they’re all in the local universe and none in the early universe,” Kalogera says. And that would tell researchers something about how massive star formation has changed throughout cosmic history. “We have high expectations now for a bigger sample in the near future.”