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  • richardmitnick 10:00 pm on January 19, 2016 Permalink | Reply
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    From LIGO: “Planning for a bright tomorrow: prospects for gravitational-wave astronomy with Advanced LIGO and Advanced Virgo” 

    Advanced Ligo

    Advanced LIGO

    LSC LIGO Scientific Collaboration

    VIRGO Collaboration bloc

    Where do you see yourself in five years? This is a dreaded interview question. It is hard to predict where you will end up in the future, as you never know what opportunities (or setbacks) you will encounter or how your interests will change. However, it is a good idea to have a plan, to think about what you want to accomplish so you can set yourself goals. Scientific collaborations also have to think about the future, and it is just as hard for us to do so. Often, we are trying to do things for the very first time so it can be difficult to judge how long they will take; however, with so many people from all around the world involved, it is extremely useful to have a plan so that we can co-ordinate our efforts.

    LIGO and Virgo have thought about where we want to be in five (and more) years, and have written up an answer. This might not be much use for job interviews, but should let other astrophysicists know what to expect. A plan was first produced back in 2013, and now we are updating it with our progress. The good news is that we are currently right on target! In fact, we are near the upper end of our expectations.

    Temp 1

    Temp 2

    Our current plan for how the sensitivity of the Advanced LIGO and Advanced Virgo detectors will progress with time. The curves on the plots show the expected strain noise across the spectrum of gravitational-wave frequencies; the strain is a good measure of the sensitivity of the detectors to gravitational waves. The lower the sensitivity curve on the plots, the better we are at measuring gravitational waves (the easier it is to detect quieter signals, like those from sources further away). We cannot predict exactly how things will go, but these are our current best estimates. The BNS-optimized curve is an idea to specially tune the detectors to search for binary neutron stars, which are expected to be one of the most common sources.

    Temp 3
    A plausible time-line for how LIGO and Virgo detectors will operate over the coming decade. Dates become more uncertain the further they are in the future. The colored bars correspond to observing runs, with the colors matching those in the sensitivity plots above. Between observing runs, we work on tuning our detectors to improve their sensitivity, and have engineering runs where we test the instruments and check that we understand how they behave while running.

    The Advanced LIGO detectors officially began their first observing run, which is called O1, on 18 September 2015.

    Temp 4
    A simulated sky map for the location of a binary neutron-star merger that could be seen in O1 (Berry et al. 2015). Darker reds indicate more probable positions and the star indicates the true location. The map allows astronomers to decide where to point their telescopes in order to have the best chance of seeing an electromagnetic counterpart. With only two detectors, we localize the source to somewhere in a circle on a sky from which the gravitational-wave signal would pass through our detectors at times that match our measurements. In these map projections, the circles look like long, extended arcs of reddish color (where the posterior probability density is high).

    The detectors are not yet at final sensitivity, but are roughly four times more sensitive than the pre-Advanced LIGO best. It is a long and complicated process to improve our gravitational-wave detectors. Rather than wait until they are at their final sensitivity before beginning observations, we plan to carry out several observing runs along the way. This is done because we are excited to start the search for gravitational waves as soon as possible; because we want to gain experience operating our detectors in stable, undisturbed observing state, and because we want to test out our data-analysis methods. Figuring out how to extract all the information we can from our data (while checking carefully for any gravitational waves that might be present) is just as tricky as getting the instruments working in the first place. O1 is planned to last for four months, closing mid-January 2016. Then work will start on upgrading the instruments for our second observing run, which is called O2; those upgrades will be informed by what we have learned about the instruments during O1. O2 will start in 2016 and last around six months. Hopefully, around this time Advanced LIGO will be joined by Advanced Virgo. Following O2 we will upgrade again, before observing for nine months in our third observing run, which is called (you can probably guess) O3. Each upgrade should improve the sensitivities of our detectors and increase our chances of detecting gravitational waves. Eventually, if all goes according to plan, both Advanced LIGO and Advanced Virgo will be running at full sensitivity by 2021.

    It is not just those impatient for the first direct detection of gravitational waves who are interested in the Advanced LIGO and Advanced Virgo observing plans. Many other astronomers are also keen to look for an explosion (or its afterglow) that accompanies a gravitational-wave event. These explosions are called electromagnetic counterparts, as observations are made with electromagnetic radiation (such as visible light, radio or gamma-rays) as well as with gravitational radiation (gravitational waves). The detection of both electromagnetic and gravitational radiation from the same source enables a more complete understanding of the physics, and simultaneous observations like these are called multi-messenger astronomy.. Some gravitational-wave sources, like merging neutron stars, may come with an accompanying electromagnetic signal while others, like merging black holes, probably do not (although that would make it more exciting if an electromagnetic counterpart were discovered). To plan their observations, astronomers need to know when we will be looking for gravitational waves and how much of the sky they will need to cover.

    When localising sources on the sky, gravitational-wave detectors work much like ears locating the source of a sound. The time difference between the signal arriving at different detectors gives information about where it came from. Adding Advanced Virgo to the network will made a huge difference in locating the source! There is also a plan to put a LIGO detector in India to enhance the network further, and within the next few years the LIGO and Virgo detectors will also be joined by a Japanese detector KAGRA that is currently under construction. The localization on the sky will improve as the detector network advances. Adding more detectors to the network will also increase the fraction of the time that we have the two or more detectors observing (which we need to make a detection). However, improving the detectors’ sensitivity will also make the network sensitive to more distant gravitational-wave sources, which would have fainter electromagnetic counterparts. Astronomers have a difficult challenge ahead of them.

    The one thing we cannot plan for is exactly when a gravitational-wave signal will pass through the Earth. However, each step of progress in detector sensitivity and data analysis increases our chance of making a detection. LIGO, Virgo and KAGRA will be detecting gravitational-wave signals soon, and perhaps there will be electromagnetic counterparts too.

    Glossary

    Electromagnetic radiation: Visible light stretches from red to violet, but outside the range our eyes can see this spectrum continues. Beyond red light there is infra-red, microwaves and radio waves, and beyond violet there is ultraviolet, X rays and gamma rays. This is the spectrum of electromagnetic radiation, and astronomers use each part of the spectrum to learn more about the Universe. All electromagnetic radiation takes the form of ripples in electric and magnetic fields, and differ in their frequency or wavelength (the length of a ripple).
    Gravitational radiation: Ripples in space-time created by accelerating massive objects. Like electromagnetic radiation, they travel at the speed of light. They are predicted by Einstein’s theory of general relativity and are commonly known as gravitational waves. If you would like to know more, you have come to the right place! Try looking at our other pages on gravitational-wave science.

    Read more:

    Free preprint of the paper on the arXiv

    See the full article here .

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    LIGO
    LIGO Hanford Observatory

     
  • richardmitnick 9:47 pm on January 13, 2016 Permalink | Reply
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    From Sky and Telescope: “About The LIGO Gravitational-Wave Rumor. . .” The Best Article on this Subject 

    SKY&Telescope bloc

    Sky & Telescope

    January 13, 2016
    Shannon Hall

    The physics and astronomy world is agossip with a rumor: has LIGO heard its first black-hole merger?

    Caltech Ligo
    MIT/Caltech Advanced aLIGO

    Rumors are swarming on social media that the newly upgraded LIGO, the Advanced Laser Interferometer Gravitational-Wave Observatory or aLIGO, has finally seen the gravitational-wave signature of two stellar-mass black holes spiraling together and merging. Maybe even two such events since September. Or not.

    Such an observation would not only confirm one of the most elusive predictions of [Albert] Einstein’s general theory of relativity, it would open a new field of cosmic observation: gravitational-wave astronomy.

    Temp 1
    Artist’s concept of gravitational waves produced by closely orbiting black holes in a 2-dimensional sheet. K. Thorne (Caltech)/ T. Carnahan (NASA GSFC)

    First, the background: According to general relativity, any accelerating mass should produce weak ripples in the fabric of spacetime itself. But it would take enormous, dense masses accelerating extremely fast to emit a significant amount of them. Neutron stars or black holes spiraling together and merging would qualify, and LIGO was built with those events particularly in mind.

    6
    Simulation of gravitational lensing by a black hole, which distorts the image of a galaxy in the background.

    7
    Radiation from the pulsar PSR B1509-58, a rapidly spinning neutron star, makes nearby gas glow in X-rays (gold, from [NASA]Chandra) and illuminates the rest of the nebula, here seen in infrared (blue and red, from [NASA] WISE)

    NASA Chandra Telescope
    Chandra

    NASA Wise Telescope
    WISE

    As gravitational waves pass by, they stress and compress time and distance. But after travelling millions of light-years across the universe, they would be extremely weak. The typical expected signal strength would stretch and squeeze the distance from the Earth to the Sun, for instance, by the width of a hydrogen atom. Yet even that weak an effect could be detected by the laser beams bouncing back and forth along LIGO’s 4-kilometer vacuum pipes. It would be the first direct detection of gravitational radiation. (We already know it exists by its indirect effect of draining orbital energy away from close neutron-star binaries.) A Nobel Prize probably awaits the first direct observation. If it ever happens.

    3
    The tunnel for one of the LIGO arms in Livingston, Louisiana. Having two units nearly 2,000 miles apart provides essential error checking and would help triangulate to find the incoming direction of any gravitational waves. A third detector in Italy, named VIRGO, is scheduled to join the network.

    Advanced Virgo
    VIRGO

    Such a feat “will open up a new window into the way we see the universe,” says astronomer Tanaka Takamitsu (Stonybrook University). Take gamma-ray bursts, for instance. These are quick, incredibly powerful explosions that are presumed to come, in some cases, from a pair of neutron stars spiraling together and merging, and in other cases from the fraction-of-a-second disruption of a dying star’s neutron-star-like core. Both kinds of cataclysm should be violent enough to send detectable gravitational waves far across the universe. “If we could see such events from gravitational-wave and conventional telescopes [both], then we can learn a lot more about the physics and what’s really going on with those events,” says Takamitsu.

    Still, the rumors remain just rumors. And they’re really bothering the LIGO people.

    Gravitational Whispers

    The gossip started spreading in physics circles just a week after the upgraded aLIGO began running in September. The rumors escaped from physics circles when cosmologist Lawrence Krauss (Arizona State University) tweeted about them on September 25th: “Rumor of a gravitational wave detection at LIGO detector. Amazing if true. Will post details if it survives.” More recently he commented that he’s 60% sure the story will pan out. Yesterday he noted the caveat that he is not one of the 900-plus members of the LIGO scientific collaboration, nor does he represent anyone there.

    Steinn Sigurdsson (Pennsylvania State University), who has also speculated on the rumors via social media, says “I have absolutely no inside information on what is going on. I hear stories, I can make inferences, I can see patterns in activity. And there has been a consistent whisper for several months now that [aLIGO] saw something as soon as they turned it on.”

    4
    Researchers work on a LIGO detector in Livingston in 2014. Michael Fyffe/LIGO

    Those whispers grew to a lively babble after further tantalizing clues. First, Sigurdsson points to a flurry of papers that have appeared this week on the arXiv preprint server that were curiously specific. Astronomers, says Sigurdsson, “posted somewhat different scenarios for ways in which you could have black hole binaries form, all of which coincidentally predicted almost the exact same final configuration, and said ‘Gosh our model predicted that this very specific sort of thing will be the most likely thing that LIGO sees.’ ” And Sigurdsson isn’t the only one who has noticed. Derek Fox (Pennsylvania State University) pointed to one paper, for example, tweeting “this seems a rather specific GW [gravitational wave] scenario to pull out of thin air?”

    Temp 1
    The meeting of the arms. The light pipes and the equipment in their ends (seen here) are kept in an ultrahigh vacuum.

    But again, Lawrence, Sigurdsson, and Takamitsu claim to have no privileged information. “It’s the equivalent of watching for pizza deliveries at the Pentagon,” says Sigurdsson. He’s referring to the open-source intelligence technique that Washington reporters reportedly used to spot when big events were about to emerge based on the number of late-night pizzas delivered to the White House. “You can play the same game with physicists,” he says. (Unfortunately there have been no reports of LIGO ordering an overabundance of Dominos.)

    Second, it’s a small community. So when a few collaborators — who all happen to be members of LIGO — duck out of a future conference due to new overlapping commitments, it doesn’t go unnoticed. A similar pattern played out right before physicists announced the discovery of the Higgs boson.

    Higgs Boson Event
    Possible Higgs event.

    Based on dates cancelled, Sigurdsson speculates that an announcement will come from the team on February 11th. Takamitsu, however, speculates that it will take months.

    Details of the supposed detection, however, were not publicly bandied about until Monday, when theoretical physicist Luboš Motl posted on his blog the latest version of the rumor: that aLIGO has picked up waves produced by two colliding black holes each with 10 or more solar masses. He also said he’s been told that two events have been detected.

    Reason for Silence

    There’s a good reason why LIGO’s people refuse to confirm or deny that something is going on. Scientists really want to get things right before they announce a major finding to the world, whether positive or negative. LIGO’s data-analysis task alone is vast and full of potential gotchas, and the most likely gravitational-wave detections would be buried deep in the noise. The experiment is looking for changes in the distance between mirrored blocks of metal 4 km apart as slight as 10–22 meter, about a millionth the diameter of a proton. In other words, changes in measurement of 1 part in 1025. What could possibly go wrong?

    Fresh on the minds of everyone in astronomy and physics is an announcement fiasco that blew up spectacularly in 2014. The astronomers of the Harvard-based BICEP2 collaboration announced to the world’s media, at a packed press conference, that they had very likely discovered primordial gravitational waves from the earliest instant of the Big Bang.

    12
    BICEP images

    BICEP 2
    BICEP 2 interior
    BICEP at the South Pole, exterior and interior

    The signal was unexpectedly strong. It would have been the much-sought, crowning evidence for the inflationary-universe theory of how the Big Bang happened. Not until later did their work go through full peer review. The discovery literally turned to dust — leaving a very public mess and a lot of criticism. Many dread a repeat.

    The current excitement could easily be a false alarm. Even if LIGO has a promising signal, it may be a false test signal planted as a drill. It’s been done before, in 2010 near the end of LIGO’s last pre-upgrade run. Three members of the LIGO team are empowered to move the mirrored blocks by just the right traces in just the right way. Only they know the truth, and the test protocol is that they not reveal a planted signal until the collaboration has finished analyzing it and is ready to publish a paper and hold a press conference. “Blind tests” like this are the gold standard in all branches of science.

    So we’ll just have to cool our heels. But maybe not for long. If the detection is real, it’s likely to be announced in February or March according to various reports. If it was just a test, this will presumably be announced in a similar time frame.

    “Essential to the Process”

    A premature “discovery” getting loose, and then being denied or retracted, could diminish the public’s trust in scientists — and the scientific process — in general. “We live in a crazy time when it comes to science and the public, as the ongoing ‘debate’ about climate change shows us again and again,” wrote astronomer Adam Frank (University of Rochester) in his NPR blog on the BICEP2 fiasco in 2014. “I wish they’d have let the usual scientific process run its course before they made such a grand announcement. If they had, odds are, it would have been clear that no such announcement was warranted — at least not yet — and we’d all be better off.”

    Sigurdsson, however, disagrees. When the BICEP2 team announced their results, he used it as an example in his cosmology 101 class, encouraging students to view it as an uncertain result in mid-discovery phase. “I think most of the public appreciates the fact that you can make mistakes for the right reasons and that’s part of the process,” says Sigurdsson. “We proceed by falsification. We make conjectures, we test them, and some of the time we find that things were wrong and we throw them out. But that’s still essential to the process. We need to get that across.”

    See the full article here .

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    Sky & Telescope magazine, founded in 1941 by Charles A. Federer Jr. and Helen Spence Federer, has the largest, most experienced staff of any astronomy magazine in the world. Its editors are virtually all amateur or professional astronomers, and every one has built a telescope, written a book, done original research, developed a new product, or otherwise distinguished him or herself.

    Sky & Telescope magazine, now in its eighth decade, came about because of some happy accidents. Its earliest known ancestor was a four-page bulletin called The Amateur Astronomer, which was begun in 1929 by the Amateur Astronomers Association in New York City. Then, in 1935, the American Museum of Natural History opened its Hayden Planetarium and began to issue a monthly bulletin that became a full-size magazine called The Sky within a year. Under the editorship of Hans Christian Adamson, The Sky featured large illustrations and articles from astronomers all over the globe. It immediately absorbed The Amateur Astronomer.

    Despite initial success, by 1939 the planetarium found itself unable to continue financial support of The Sky. Charles A. Federer, who would become the dominant force behind Sky & Telescope, was then working as a lecturer at the planetarium. He was asked to take over publishing The Sky. Federer agreed and started an independent publishing corporation in New York.

    “Our first issue came out in January 1940,” he noted. “We dropped from 32 to 24 pages, used cheaper quality paper…but editorially we further defined the departments and tried to squeeze as much information as possible between the covers.” Federer was The Sky’s editor, and his wife, Helen, served as managing editor. In that January 1940 issue, they stated their goal: “We shall try to make the magazine meet the needs of amateur astronomy, so that amateur astronomers will come to regard it as essential to their pursuit, and professionals to consider it a worthwhile medium in which to bring their work before the public.”

     
  • richardmitnick 12:26 pm on January 12, 2016 Permalink | Reply
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    From GIZMODO: “Rumors Are Flying That We Finally Found Gravitational Waves” 

    GIZMODO bloc

    GIZMODO

    1.11.16
    Jennifer Ouellette

    1

    Excited rumors began circulating on Twitter this morning that a major experiment designed to hunt for gravitational waves—ripples in the fabric of spacetime first predicted by Albert Einstein—has observed them directly for the very first time. If confirmed, this would be one of the most significant physics discoveries of the last century.

    Move a large mass very suddenly—or have two massive objects suddenly collide, or a supernova explode—and you would create ripples in space-time, much like tossing a stone in a still pond. The more massive the object, the more it will churn the surrounding spacetime, and the stronger the gravitational waves it should produce. Einstein predicted their existence in his general theory of relativity back in 1915, but he thought it would never be possible to test that prediction.

    LIGO (Laser Interferometer Gravitational Wave Observatory) is one of several experiments designed to hunt for these elusive ripples, and with its latest upgrade to Advanced LIGO, completed last year, it has the best chance of doing so.

    Caltech Ligo
    MIT/Caltech Advanced LIGO

    In fact, it topped our list of physics stories to watch in 2016.

    There have been excited rumors about a LIGO discovery before, most notably a mere week after the upgraded experiment began operations last fall. Lawrence Krauss, a physicist at Arizona State University, spilled the beans on Twitter, giving it a 10- to 15-percent chance of being true. “The official response is that we’re analyzing the data,” LIGO spokesperson Gabriela González (Louisiana State University) told Nature at the time.

    Now it seems the rumors have resurfaced, and Krauss has been blabbing again:

    Lawrence Krauss at Twitter
    “My earlier rumor about LIGO has been confirmed by independent sources. Stay tuned! Gravitational waves may have been discovered!! Exciting.”

    We’re guessing that once again, the official response will be that they’re currently analyzing the data and everyone should just be patient, because you can’t rush this kind of tricky analysis. TL;DR: They will neither confirm nor deny the rumor.

    UPDATE 3:18 PM: Alan Weinstein, who heads the LIGO group at Caltech, had this to say via email: “My response to you is no more or less than the official one, which is the truth: ‘We are analyzing 01 data and will share news when ready.’ I’d say that it is wisest to just be patient.”

    That’s good advice in general when rumors of exciting breakthroughs begin circulating. But in this case, it’s quite possible that they are true. Loyola University physicist Robert McNees pointed out on Twitter that he’d only made one prediction for physics breakthroughs in 2016: that Advanced LIGO would directly detect gravitational waves. And he certainly wasn’t the only one to do so. He also had a few things to say about this brave new world we live in, where big physics news inevitably leaks out onto social media:

    [See Robert McNees at Twitter.]

    “I guess I’d say that rumors just reflect how excited we all get about the prospect of new discoveries. It’s natural to feel that way! But the last thing we want to do is jump the gun,” McNees told Gizmodo via Twitter DM. “The best way to support these scientists is to let them carry out their experiments and analysis the way they were meant to be done. Let them take the time to do things the right way! And as physicists, I think we need to greet the inevitable rumors with explanations of how science works and why it’s so important to be careful. Even if that means having to wait for exciting news.”

    Sigh. Fine. We’ll be hanging onto the edge of our seats waiting for official confirmation one way or the other. If true—well, it’s a hell of a way to kick off 2016. And it would probably be a shoo-in for this year’s Nobel Prize in Physics.

    See the full article here .

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    “We come from the future.”

    GIZMOGO pictorial

     
  • richardmitnick 5:36 pm on December 14, 2015 Permalink | Reply
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    From FNAL: “Gravitational wave hunters team with astrophysicists” 

    FNAL II photo

    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    December 14, 2015
    Chris Patrick

    The Dark Energy Camera [DECam], built to map the southern sky, sits inside a telescope in Chile.

    Fermilab DECam
    DECam, built at FNAL

    As its name suggests, it helps scientists to look for the origin of dark energy, the mysterious force that pushes the universe apart.

    Now the camera has another job: It’s acting as eyes in the hunt for sources of gravitational waves.

    A massive object, such as a star or a black hole, distorts the fabric of space — sort of the way a bowling ball bends the surface of a trampoline. If the object is accelerating, this distortion pulses outward in ripples traveling at the speed of light. These ripples are gravitational waves. But nobody has been able to record them so far.

    “Gravitational waves are sort of the last prediction of [Albert] Einstein’s that has yet to be experimentally verified,” said Rick Kessler, senior research associate at the University of Chicago.

    Theory predicts that even puny humans make gravitational waves. But because our mass and accelerations are small, they’re too weak to notice. Most gravitational waves are. That’s why scientists haven’t directly detected them yet, although Albert Einstein predicted their existence 100 years ago.

    There is indirect evidence that gravitational waves exist. It comes from a particular system of two neutron stars orbiting each other about 20,000 light-years away from Earth. Scientists have monitored the dizzying dance of these compact stars, together known as the Hulse-Taylor system, for more than 40 years.

    Einstein predicted that gravitational waves carry energy away from a system. Removing energy from two orbiting objects shrinks their paths as if they were being lassoed together. The objects get closer and closer until, eventually, they merge in a cataclysmic collision.

    Watching the stars in the Hulse-Taylor system gradually fall toward each other gives scientists indirect evidence that Einstein was right (again) — these neutron stars are losing energy in the form of gravitational waves, exactly as predicted.

    “But we’re experimentalists,” Kessler said. “We want direct evidence.”

    That’s where the Laser Interferometer Gravitational-wave Observatory comes in.

    Caltech Ligo
    Advanced LIGO

    Scientists built LIGO in an attempt to detect gravitational waves for the first time. And to find out more about the sources of potential gravitational waves, LIGO scientists are now coordinating their measurements with observations made by the Dark Energy Camera on the Blanco Telescope [pictured below].

    1
    DES-GW is using the Dark Energy Camera in the Blanco Telescope in Chile to look for sources of gravitational waves. The red, orange and yellow areas the inset represent gravitational waves, and the bright light represents the source of these waves. The thin white arc illustrates a narrow area of sky where LIGO scientists believe a gravitational wave may have originated.

    LIGO, funded by the National Science Foundation and other public and private institutions, has two detectors. One resides in Louisiana, the other in the state of Washington. They’re L-shaped, each outfitted with two perpendicular arms 2.5 miles long. Lasers shoot through the arms and bounce off mirrors that send them back to their source to combine and form what are known as interference patterns. Observing changes to these interference patterns due changes in space-time is key to directly detecting gravitational waves. That’s because gravitational waves ever so slightly squeeze and then stretch space, drawing separated points of matter a smidge closer together and then a smidge further apart.

    The strongest space-time ripples are produced by violent cosmic events like the merging of two neutron stars (which will happen to the Hulse-Taylor system in 300 million years) or the collision of two black holes. Although these waves are actually quite feeble by the time they travel a few hundred million light-years to Earth, they will almost imperceptibly squeeze and stretch LIGO’s detector arms.

    This faint manipulation will temporarily shorten or lengthen the detectors’ arms by 1,000 times less than the size of a proton. Changing the arm length alters the distance the lasers travel, which will show up as a slight shift in their interference pattern. Scientists can then read the interference pattern like a gravitational wave’s fingerprint, giving them direct evidence that space-time ripples exist.

    “The detectors will tell us that a gravitational wave came from somewhere in a banana-shaped band of sky,” said Daniel Holz, associate professor at the University of Chicago who is on the LIGO experiment. “The problem is that the band is very large. It’s on the order of 400 times the size of the full moon.”

    Although LIGO can point scientists in the general direction from which gravitational wave came, it can’t pick out the exact location of the source.

    “That’s why they need the eyes of the Dark Energy Camera to go look in that general direction,” said Marcelle Soares-Santos, associate scientist at the U.S. Department of Energy’s Fermilab.

    Members of the Dark Energy Survey, including Soares-Santos and other Fermilab scientists, have partnered with LIGO in the hunt for gravitational waves. They’re calling themselves the DES-GW group. Holz, who is also a member of DES-GW, said the team is a mixture of both gravitational wave and dark energy survey experts.

    DES-GW will use the Dark Energy Camera to help LIGO search for the source of the gravitational waves it detects. Unlike most telescopes, the Dark Energy Camera is just the right size and has the right sensitivity to act as LIGO’s eyes. It can cover the banana-shaped area of the sky that LIGO looks at in 20 to 30 images.

    When LIGO thinks it’s detected a gravitational wave, it will alert DES-GW collaborators, who will alert the Dark Energy Camera operators. LIGO and DES-GW have already joined forces and begun working together during the current season.

    “With the Dark Energy Camera we’re trying to find an optical signature that accompanies the gravitational waves,” said Kessler, who is also a member of DES-GW.

    “This is the frontier of science — we don’t really know what we’ll see,” Holz said. “But there’s an expectation that some systems will emit light at the same time as gravitational waves.”

    Using the Dark Energy Camera to see this light, the optical signature of the gravitational waves’ source, could tell scientists more about the systems that produce them. This system may be made up of two neutron stars, two black holes or a neutron-black hole pair. And it would make history.

    “We would be the first ones to directly detect gravitational waves and see light from the same event,” Soares-Santos said.

    Soares-Santos is most excited about the potential of using this light as a tool to reconstruct the history of expansion of the universe, the same way supernovae are used today.

    “There are lots of ifs and maybes,” Soares-Santos said of this possibility. “But at the same time, it’s exciting.”

    Holz finds the most thrill in the prospect of surprise.

    “Since we’ve never measured the universe in this way before, we just don’t know what’s out there,” Holz said. “That’s the real excitement.”

    See the full article here .

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    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 2:35 pm on April 23, 2015 Permalink | Reply
    Tags: Advanced LIGO, , ,   

    From Advanced LIGO: “Advanced LIGO — The Next Step in Gravitational Wave Astronomy” 

    Advanced Ligo

    Advanced LIGO

    Gravitational waves offer a remarkable opportunity to see the universe from a new perspective, providing access to astrophysical insights that are available in no other way. The Initial LIGO gravitational wave detectors completed observations at and beyond their original design sensitivity in 2007, and the data have been interpreted to establish new upper limits on gravitational-wave flux. An additional data run with the modified Enhanced LIGO detectors reached completion in 2010. The Advanced LIGO project will completely upgrade the three U.S. gravitational wave interferometers, bringing these instruments to sensitivities that should make gravitational wave detections a routine occurrence. The U.S. National Science Foundation leads in financial support for Advanced LIGO. Funding organizations in Germany, the U.K. and Australia also have made significant commitments to the project. Together with Advanced Virgo, Advanced LIGO will bring gravitational wave astronomy to maturity.

    See the full article here.

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    LIGO Hanford Observatory

     
  • richardmitnick 2:02 pm on March 30, 2015 Permalink | Reply
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    From Caltech: “New NSF-Funded Physics Frontiers Center Expands Hunt for Gravitational Waves” 

    Caltech Logo
    Caltech

    03/30/2015
    Kathy Svitil

    1
    Gravitational waves are ripples in space-time (represented by the green grid) produced by interacting supermassive black holes in distant galaxies. As these waves wash over the Milky Way, they cause minute yet measurable changes in the arrival times at Earth of the radio signals from pulsars, the Universe’s most stable natural clocks. These telltale changes can be detected by sensitive radio telescopes, like the Arecibo Observatory in Puerto Rico and the Green Bank Telescope in West Virginia. Credit: David Champion

    The search for gravitational waves—elusive ripples in the fabric of space-time predicted to arise from extremely energetic and large-scale cosmic events such as the collisions of neutron stars and black holes—has expanded, thanks to a $14.5-million, five-year award from the National Science Foundation for the creation and operation of a multi-institution Physics Frontiers Center (PFC) called the North American Nanohertz Observatory for Gravitational Waves (NANOGrav).

    The NANOGrav PFC will be directed by Xavier Siemens, a physicist at the University of Wisconsin–Milwaukee and the principal investigator for the project, and will fund the NANOGrav research activities of 55 scientists and students distributed across the 15-institution collaboration, including the work of four Caltech/JPL scientists—Senior Faculty Associate Curt Cutler; Visiting Associates Joseph Lazio and Michele Vallisneri; and Walid Majid, a visiting associate at Caltech and a JPL research scientist—as well as two new postdoctoral fellows at Caltech to be supported by the PFC funds. JPL is managed by Caltech for NASA.

    “Caltech has a long tradition of leadership in both the theoretical prediction of sources of gravitational waves and experimental searches for them,” says Sterl Phinney, professor of theoretical astrophysics and executive officer for astronomy in the Division of Physics, Mathematics and Astronomy. “This ranges from waves created during the inflation of the early universe, which have periods of billions of years; to waves from supermassive black hole binaries in the nuclei of galaxies, with periods of years; to a multitude of sources with periods of minutes to hours; to the final inspiraling of neutron stars and stellar mass black holes, which create gravitational waves with periods less than a tenth of a second.”

    The detection of the high-frequency gravitational waves created in this last set of events is a central goal of Advanced LIGO (the next-generation Laser Interferometry Gravitational-Wave Observatory), scheduled to begin operation later in 2015. LIGO and Advanced LIGO, funded by NSF, are comanaged by Caltech and MIT.

    “This new Physics Frontier Center is a significant boost to what has long been the dark horse in the exploration of the spectrum of gravitational waves: low-frequency gravitational waves,” Phinney says. These gravitational waves are predicted to have such a long wavelength—significantly larger than our solar system—that we cannot build a detector large enough to observe them. Fortunately, the universe itself has created its own detection tool, millisecond pulsars—the rapidly spinning, superdense remains of massive stars that have exploded as supernovas. These ultrastable stars appear to “tick” every time their beamed emissions sweep past Earth like a lighthouse beacon. Gravitational waves may be detected in the small but perceptible fluctuations—a few tens of nanoseconds over five or more years—they cause in the measured arrival times at Earth of radio pulses from these millisecond pulsars.

    NANOGrav makes use of the Arecibo Observatory in Puerto Rico and the National Radio Astronomy Observatory’s Green Bank Telescope (GBT), and will obtain other data from telescopes in Europe, Australia, and Canada. The team of researchers at Caltech will lead NANOGrav’s efforts to develop the approaches and algorithms for extracting the weak gravitational-wave signals from the minute changes in the arrival times of pulses from radio pulsars that are observed regularly by these instruments.

    Arecibo Observatory
    Arecibo Radio Observatory Telescope

    NRAO GBT
    NRAO/GBT

    See the full article here.

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