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  • richardmitnick 1:30 pm on July 29, 2016 Permalink | Reply
    Tags: , , Black Holes,   

    From CfA: “The Aligned Spin of a Black Hole” 

    Smithsonian Astrophysical Observatory
    Smithsonian Astrophysical Observatory

    July 29, 2016
    No writer credit

    1
    An artist’s conception of an X-ray emitting black hole binary system. A new study has measured the spin of one notable example and confirmed, contrary to some earlier claims, that the spin is aligned with the spin of the accretion disk. NASA/ESA

    A black hole in traditional theory is characterized by having “no hair,” that is, it is so simple that it can be completely described by just three parameters, its mass, its spin, and its electric charge. Even though it may have formed out of a complex mix of matter and energy, all the specific details are lost when it collapses to a singular point. This is surrounded by a “horizon,” and once anything – matter or light (energy) – falls within that horizon, it cannot escape. Hence, the singularity appears black. Outside this horizon a rotating, accreting disk can radiate freely.

    Astronomers are able to measure the spins of black holes by closely modeling the X-ray radiation from the environment in one of two ways: fitting the continuum emission spectrum, or modeling the shape of an emission iron line from very highly ionized iron. So far the spins of ten stellar-mass black holes have been determined and the robustness of the continuum-fitting method has been well demonstrated. Recently one bright black hole, “Nova Muscae 1991,” was found to be rotating in a sense opposite to the spin of its disk, a very unusual and curious result since both might be expected to develop somewhat in concert. The spin of this black hole had previously determined to be small, about ten percent of the limit allowed by relativity.

    CfA astronomers Jeff McClintock, James Steiner and Jainfeng Wu and their colleagues have re-reduced archival data for this source, and obtained much improved measurements for the three key parameters needed in the continuum-fitting method: mass (11.0 solar-masses), disk inclination (43.2 degrees), and distance (16,300 light-years), each with a corresponding (and modest) uncertainty. Using the new numbers to reevaluate the model of the Nova Muscae 1991 spin, the scientists report that the spin is actually about five times larger than previously estimated. More significantly, that the spin is definitely prograde (aligned with the direction of the disk spin), and not retrograde. The new results resolve a potential mystery, and offer a confirmation of the general methods for modeling black holes.

    Reference(s):

    The Spin of The Black Hole in the X-ray Binary Nova Muscae 1991, Zihan Chen, Lijun Gou, Jeffrey E. McClintock, James F. Steiner, Jianfeng Wu, Weiwei Xu, Jerome A. Orosz, and Yanmei Xiang, ApJ 825, 45, 2016.

    See the full article here .

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    About CfA

    The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy. The long relationship between the two organizations, which began when the SAO moved its headquarters to Cambridge in 1955, was formalized by the establishment of a joint center in 1973. The CfA’s history of accomplishments in astronomy and astrophysics is reflected in a wide range of awards and prizes received by individual CfA scientists.

    Today, some 300 Smithsonian and Harvard scientists cooperate in broad programs of astrophysical research supported by Federal appropriations and University funds as well as contracts and grants from government agencies. These scientific investigations, touching on almost all major topics in astronomy, are organized into the following divisions, scientific departments and service groups.

     
  • richardmitnick 9:23 am on July 26, 2016 Permalink | Reply
    Tags: , , Black Holes,   

    From Science Alert: “Astronomers just discovered a “stealth black hole” hiding inside our galaxy” 

    ScienceAlert

    Science Alert

    1
    Image: X-ray: NASA/CXC/Univ. of Alberta/B.Tetarenko et al; Optical: NASA/STScI; Radio: NSF/NRAO/VLA/Curtin Univ./J. Miller-Jones

    28 JUN 2016
    DAVID NIELD

    Scientists have just discovered a ‘hidden’ black hole, called VLA J2130+12, hiding inside the Milky Way. The reason it has eluded astronomers until now is that it hasn’t been acting the way black holes normally do.

    Simply put, this black hole is quieter than we might expect and is in many ways a “stealth black hole”, as one of the astronomers describes it. It’s pulling in nearby material, like all black holes do, but at a very slow rate – and that’s why it’s previously been missed.

    What’s more, the new discovery indicates there might be millions of these stealth black holes hidden across the Universe waiting to be discovered. Astronomers: recalibrate your telescopes.

    Spotting black holes isn’t quite as simple as pointing a telescope at the sky – we can only really ‘see’ them based on the effect they have on nearby matter, which means these celestial phenomena can go undetected for a very long time.

    “Usually, we find black holes when they are pulling in lots of material,” explained lead researcher Bailey Tetarenko from the University of Alberta in Canada. “Before falling into the black hole this material gets very hot and emits brightly in X-rays. This one is so quiet that it’s practically a stealth black hole.”

    A “peculiar” source of radio waves first tipped off experts to the presence of this black hole.

    These radio waves were being emitted as strongly as if they were coming from a black hole, but the researchers were only detecting faint pulses of X-rays, which doesn’t match up with our understanding of how black holes work. The team realised that these weak X-rays were a result of the black hole working so slowly.

    VLA J2130+12 has about one-tenth to one-fifth the mass of our own Sun and is 7,200 light-years away, which is well inside our own Milky Way. According to the researchers behind the new discovery, some of these hidden black holes could be even closer to Earth: thankfully though they’ll still be many light years away, so there’s no danger of us being sucked into a void just yet.

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    Astronomers used data from some serious bits of space kit to work out exactly what VLA J2130+12 is. They combined readings from NASA’s Chandra X-ray Observatory, the Hubble Space Telescope, and the Karl G. Jansky Very Large Array (VLA).

    Many more regions of the sky will need to be mapped in this kind of detail if we’re to spot other stealth black holes like this one.

    “Unless we were incredibly lucky to find one source like this in a small patch of the sky, there must be many more of these black hole binaries in our Galaxy than we used to think,” said one of the researchers, Arash Bahramian from the University of Alberta.

    The findings are published in The Astrophysical Journal.

    See the full article here .

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  • richardmitnick 3:39 pm on July 18, 2016 Permalink | Reply
    Tags: , , Black Holes, , OJ 287   

    From New Scientist: “Einstein’s clock: The doomed black hole to set your watch by” 

    NewScientist

    New Scientist

    18 July 2016
    Joshua Sokol

    1
    Caltech/NASA

    Ladies and gentlemen, your challenger. Meet a black hole new to the neighbourhood, weighing 140 million suns. That’s nothing to sneeze at: this plucky upstart is 35 times more massive than the black hole that holds court at the centre of our Milky Way.

    And now, make way for the current champion: a black hole with a mass of 18 billion suns.

    For front-row seats to this cosmic boxing match, you’ll want to (cautiously) approach OJ 287, the core region of a galaxy 3.5 billion light years away.

    1
    OJ 287

    Here, the smaller black hole orbits its larger rival. With every trip around, it falls closer, on track to be swallowed up in about 10,000 years. But in the meantime, it’s putting up an admirable fight.

    Even though the system is so far away, OJ 287 releases enough energy to appear about as bright in the sky as Pluto. We’ve been capturing it on photographic plates since the 1880s, but it first caught the eye of Mauri Valtonen at Finland’s Tuorla Observatory in Turku almost a century later. His team noticed that unlike other galactic centres, which brighten and dim sporadically, this one seemed to keep to a tight schedule. Every 12 years, it has an outburst.

    Well, not exactly every 12 years. Not only do the outbursts look different each time, but the gap between them seems to grow shorter by about 20 days each cycle. In the decades since we noticed the pattern, we’ve gone a long way towards figuring out why.

    Ancient enemies

    OJ 287’s situation is a window into what must have happened in galaxies all over the universe. Galaxies grow by eating their own kind, and almost all of them come with a supermassive black hole at the centre.

    Once two galaxies merge, their black holes – now forced to live in one new mega-galaxy – will either banish their rival with a gravitational kick that flings their opponent out of the galaxy, or eventually merge into an even bigger black hole.

    In OJ 287, the smaller black hole is en route to becoming a snack for the larger one. The larger one is also growing from a surrounding disc of gas and dust, the material from which slowly swirls down the drain. Each time the smaller black hole completes an orbit, it comes crashing through this disc at supersonic speeds.

    That violent impact blows bubbles of hot gas that expand, thin out, and then unleash a flood of ultraviolet radiation – releasing as much energy as 20,000 supernova explosions in the same spot. You could stand 36 light years away and tan faster than you would from the sun on Earth.

    The cymbal clash to come

    Even with all this thrashing, the smaller black hole has no chance of escape. Energy leaches away from the binary orbit, bringing the pair closer together and making each cycle around the behemoth a little shorter than the last.

    Although the outbursts may be impressive, the black holes’ orbital dance emits tens of thousands of times more energy as undulations in space time called gravitational waves.

    Last year, the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the US offered a preview of the endgame of OJ 287 in miniature. Twice in 2015, LIGO heard gravitational waves from the final orbits of black-hole pairs in which each black hole was a few dozen times the size of the sun, and then the reverberations of the single one left behind.

    Because its black holes are so massive, the ultimate collision at the heart of OJ 287 will be too low-frequency for LIGO to hear. But the outcome will be much the same. Where once two black holes from two separate galaxies tussled, one black hole will remain, smug and secure at the centre.

    See the full article here .

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  • richardmitnick 4:17 pm on July 12, 2016 Permalink | Reply
    Tags: , , Black Holes, Gravitational vortex, ,   

    From U Cambridge: “Gravitational vortex provides new way to study matter close to a black hole” 

    U Cambridge bloc

    Cambridge University

    12 Jul 2016
    No writer credit found

    1
    Illustration of gravitational vortex. Credit: ESA/ATG medialab

    An international team of astronomers has proved the existence of a ‘gravitational vortex’ around a black hole, solving a mystery that has eluded astronomers for more than 30 years. The discovery will allow astronomers to map the behaviour of matter very close to black holes. It could also open the door to future investigation of Albert Einstein’s general relativity.

    Matter falling into a black hole heats up as it plunges to its doom. Before it passes into the black hole and is lost from view forever, it can reach millions of degrees. At that temperature it shines x-rays into space.

    In the 1980s, astronomers discovered that the x-rays coming from black holes vary on a range of timescales and can even follow a repeating pattern with a dimming and re-brightening taking 10 seconds to complete. As the days, weeks and then months progress, the pattern’s period shortens until the oscillation takes place 10 times every second. Then it suddenly stops altogether.

    This phenomenon was dubbed a Quasi Periodic Oscillation (QPO). During the 1990s, astronomers began to suspect that the QPO was associated with a gravitational effect predicted by Einstein’s general relativity which suggested that a spinning object will create a kind of gravitational vortex. The effect is similar to twisting a spoon in honey: anything embedded in the honey will be ‘dragged’ around by the twisting spoon. In reality, this means that anything orbiting around a spinning object will have its motion affected. If an object is orbiting at an angle, its orbit will ‘precess’ – in other words, the whole orbit will change orientation around the central object. The time for the orbit to return to its initial condition is known as a precession cycle.

    In 2004, NASA launched Gravity Probe B to measure this so-called Lense-Thirring effect around Earth.

    NASA/Gravity Probe B
    NASA/Gravity Probe B

    By analysing the resulting data, scientists confirmed that the spacecraft would turn through a complete precession cycle once every 33 million years. Around a black hole, however, the effect would be much stronger because of the stronger gravitational field: the precession cycle would take just a matter of seconds to complete, close to the periods of the QPOs.

    An international team of researchers, including Dr Matt Middleton from the Institute of Astronomy at the University of Cambridge, has used the European Space Agency’s XMM-Newton and NASA’s NuSTAR, both x-ray observatories, to study the effect of black hole H1743-322 on a surrounding flat disc of matter known as an ‘accretion disk’.

    ESA/XMM Newton
    ESA/XMM Newton

    NASA/NuSTAR
    NASA/NuSTAR

    Close to a black hole, the accretion disc puffs up into a hot plasma, a state of matter in which electrons are stripped from their host atoms – the precession of this puffed up disc has been suspected to drive the QPO. This can also explain why the period changes – the place where the disc puffs up gets closer to the black hole over weeks and months, and, as it gets closer to the black hole, the faster its Lense-Thirring precession becomes.

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    The plasma releases high energy radiation that strikes the matter in the surrounding accretion disc, making the iron atoms in the disc shine like a fluorescent light tube. Instead of visible light, the iron releases X-rays of a single wavelength – referred to as ‘a line’. Because the accretion disc is rotating, the iron line has its wavelength distorted by the Doppler effect: line emission from the approaching side of the disc is squashed – blue shifted – and line emission from the receding disc material is stretched – red shifted. If the plasma really is precessing, it will sometimes shine on the approaching disc material and sometimes on the receding material, making the line wobble back and forth over the course of a precession cycle.

    It is this ‘wobble’ that has been observed by the researchers.

    “Just as general relativity predicts, we’ve seen the iron line wobble as the accretion disk orbits the black hole,” says Dr Middleton. “This is what we’d expect from matter moving in a strong gravitational field such as that produced by a black hole.”

    This is the first time that the Lense-Thirring effect has been measured in a strong gravitational field. The technique will allow astronomers to map matter in the inner regions of accretion discs around back holes. It also hints at a powerful new tool with which to test general relativity. Einstein’s theory is largely untested in such strong gravitational fields. If astronomers can understand the physics of the matter that is flowing into the black hole, they can use it to test the predictions of general relativity as never before – but only if the movement of the matter in the accretion disc can be completely understood.

    “We need to test Einstein’s general theory of relativity to breaking point,” adds Dr Adam Ingram, the lead author at the University of Amsterdam. “That’s the only way that we can tell whether it is correct or, as many physicists suspect, an approximation – albeit an extremely accurate one.”

    Larger X-ray telescopes in the future could help in the search because they could collect the X-rays faster. This would allow astronomers to investigate the QPO phenomenon in more detail. But for now, astronomers can be content with having seen Einstein’s gravity at play around a black hole.

    See the full article here .

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    U Cambridge Campus

    The University of Cambridge (abbreviated as Cantab in post-nominal letters) is a collegiate public research university in Cambridge, England. Founded in 1209, Cambridge is the second-oldest university in the English-speaking world and the world’s fourth-oldest surviving university. It grew out of an association of scholars who left the University of Oxford after a dispute with townsfolk. The two ancient universities share many common features and are often jointly referred to as “Oxbridge”.

    Cambridge is formed from a variety of institutions which include 31 constituent colleges and over 100 academic departments organised into six schools. The university occupies buildings throughout the town, many of which are of historical importance. The colleges are self-governing institutions founded as integral parts of the university. In the year ended 31 July 2014, the university had a total income of £1.51 billion, of which £371 million was from research grants and contracts. The central university and colleges have a combined endowment of around £4.9 billion, the largest of any university outside the United States. Cambridge is a member of many associations and forms part of the “golden triangle” of leading English universities and Cambridge University Health Partners, an academic health science centre. The university is closely linked with the development of the high-tech business cluster known as “Silicon Fen”.

     
  • richardmitnick 6:50 am on July 7, 2016 Permalink | Reply
    Tags: , , Black Holes, ,   

    From Stanford: “Stanford researchers help to explain how stars are born, cosmic structures evolve” 

    Stanford University Name
    Stanford University

    July 6, 2016
    Manuel Gnida

    An international team of scientists including Stanford researchers unveiled new findings on understanding the dynamic behavior of galaxy clusters and ties to cosmic evolution.

    Working with information sent from the Japanese Hitomi satellite, an international team of researchers that include Stanford scientists has obtained the first views of a supermassive black hole stirring hot gas at the heart of a galaxy cluster, like a spoon stirring cream into coffee.

    JAXA/Hitomi telescope

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    This image created by physicists at Stanford’s SLAC National Accelerator Laboratory illustrates how supermassive black holes at the center of galaxy clusters could heat intergalactic gas, preventing it from cooling and forming stars. (Image credit: SLAC National Accelerator Laboratory)

    These motions could explain why galaxy clusters form far fewer stars than expected – a puzzling property that affects the way cosmic structures evolve.

    The data, published today in Nature, were recorded with the X-ray satellite during its first month in space earlier this year, just before it spun out of control and disintegrated due to a chain of technical malfunctions.

    “Being able to measure gas motions is a major advance in understanding the dynamic behavior of galaxy clusters and its ties to cosmic evolution,” said study co-author Irina Zhuravleva, a postdoctoral researcher at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC). “Although the Hitomi mission ended tragically after a very short period of time, it’s fair to say that it has opened a new chapter in X-ray astronomy.”

    KIPAC is a joint institute of Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory.

    Galaxy clusters, which consist of hundreds to thousands of individual galaxies held together by gravity, also contain large amounts of gas. Over time, the gas should cool down and clump together to form stars. Yet there is very little star formation in galaxy clusters, and until now scientists were not sure why.

    Norbert Werner, a research associate at KIPAC involved in the data analysis, said, “We already knew that supermassive black holes, which are found at the center of all galaxy clusters and are tens of billions of times more massive than the sun, could play a major role in keeping the gas from cooling by somehow injecting energy into it. Now we understand this mechanism better and see that there is just the right amount of stirring motion to produce enough heat.”

    Plasma bubbles stir

    About 15 percent of the mass of galaxy clusters is gas that is so hot – tens of millions of degrees Fahrenheit – that it shines in bright X-rays. In their study, the Hitomi researchers looked at the Perseus cluster, one of the most massive astronomical objects and the brightest in the X-ray sky.

    Other space missions before Hitomi, including NASA’s Chandra X-ray Observatory, had taken precise X-ray images of the Perseus cluster.

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    Perseus cluster. Chandra.

    These snapshots revealed how giant bubbles of ultra-hot, ionized gas, or plasma, rise from the central supermassive black hole as it catapults streams of particles tens of thousands of light-years into space.

    Additional images of visible light from the cluster showed streaks of cold gas that appear to get pulled away from the center of the galaxy. However, until now it has been unclear what effect the plasma bubbles have on this intergalactic gas.

    To find out, the researchers pointed one of Hitomi’s instruments – the soft X-ray spectrometer (SXS) – at the center of the Perseus cluster and analyzed its X-ray emissions.

    5
    Perseus cluster. Hitomi Collaboration / JAXA / NASA / ESA / SRON / CSA

    Steve Allen, a co-principal investigator and a professor of physics at Stanford and of particle physics and astrophysics at SLAC, said, “Since the SXS had 30 times better energy resolution than the instruments of previous missions, we were able to resolve details of the X-ray signals that weren’t accessible before. These new details resulted in the very first velocity map of the cluster center, showing the speed and turbulence of the hot gas.”

    By superimposing this map onto the other images, the researchers were able to link the observed motions to the plasma bubbles.

    Zhuravleva said, “From what we’ve seen in our data, the rising bubbles drag gas from the cluster center, which explains the filaments of stretched gas in the optical images. In this process, turbulence develops. In a way, the bubbles are like spoons that stir milk into a cup of coffee and cause eddies. The turbulence, in turn, heats the gas and suppresses star formation in the cluster.”

    Hitomi’s legacy

    Astrophysicists can use the new information to fine-tune models that describe how galaxy clusters change over time.

    One important factor in these models is the mass of galaxy clusters, which researchers typically calculate from the gas pressure in the cluster. However, motions cause additional pressure, and before this study it was unclear if the calculations need to be corrected for turbulent gas.

    “Although the motions heat the gas at the center of the Perseus cluster, their speed is only about 100 miles per second, which is surprisingly slow considering how disturbed the region looks in X-ray images,” said co-principal investigator Roger Blandford, the Luke Blossom Professor of Physics at Stanford and a professor of particle physics and astrophysics at SLAC. “One consequence is that corrections for these motions are only very small and don’t affect our mass calculations much.”

    Although the loss of Hitomi cut most of the planned science program short – it was supposed to run for at least three years – the researchers hope their results will convince the international community to plan another X-ray space mission.

    Werner said, “The data Hitomi sent back to Earth are just beautiful. They demonstrate what’s possible in the field and give us a taste of all the great science that should have come out of the mission over the years.”

    Hitomi is a joint project, with the Japan Aerospace Exploration Agency (JAXA) and NASA as the principal partners. Led by Japan, it is a large-scale international collaboration, boasting the participation of eight countries, including the United States, the Netherlands and Canada, with additional partnership by the European Space Agency (ESA). Other KIPAC researchers involved in the project are Tuneyoshi Kamae, Ashley King, Hirokazu Odaka and co-principal investigator Grzegorz Madejski.

    See the full article here .

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    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

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  • richardmitnick 6:59 am on July 6, 2016 Permalink | Reply
    Tags: , , Black Holes, ,   

    From RAS: “Earth-size telescope tracks the aftermath of a star being swallowed by a supermassive black hole” 

    Royal Astronomical Society

    Royal Astronomical Society

    05 July 2016
    Media contact

    Robert Cumming
    Communications Officer
    Onsala Space Observatory
    Chalmers University of Technology
    Sweden
    Tel: +46 70 493 3114 or +46 (0)31 772 5500
    robert.cumming@chalmers.se

    Science contact

    Jun Yang
    Onsala Space Observatory
    Chalmers University of Technology
    Sweden
    Tel: +46 (0)31 7725531
    jun.yang@chalmers.se

    Radio astronomers have used a radio telescope network the size of the Earth to zoom in on a unique phenomenon in a distant galaxy: a jet activated by a star being consumed by a supermassive black hole. The record-sharp observations reveal a compact and surprisingly slowly moving source of radio waves, with details published in a paper in the journal Monthly Notices of the Royal Astronomical Society. The results will also be presented at the European Week of Astronomy and Space Science in Athens, Greece, on Friday 8 July 2016.

    1
    This artist’s impression shows the remains of a star that came too close to a supermassive black hole. Extremely sharp observations of the event Swift J1644+57 with the radio telescope network EVN (European VLBI Network) have revealed a remarkably compact jet, shown here in yellow. Image credit: ESA/S. Komossa/Beabudai Design.

    The international team, led by Jun Yang (Onsala Space Observatory, Chalmers University of Technology, Sweden), studied the new-born jet in a source known as Swift J1644+57 with the European VLBI Network (EVN), an Earth-size radio telescope array.

    European VLBI
    European VLBI

    When a star moves close to a supermassive black hole it can be disrupted violently. About half of the gas in the star is drawn towards the black hole and forms a disc around it. During this process, large amounts of gravitational energy are converted into electromagnetic radiation, creating a bright source visible at many different wavelengths.

    One dramatic consequence is that some of the star’s material, stripped from the star and collected around the black hole, can be ejected in extremely narrow beams of particles at speeds approaching the speed of light. These so-called relativistic jets produce strong emission at radio wavelengths.

    The first known tidal disruption event that formed a relativistic jet was discovered in 2011 by the NASA satellite Swift. Initially identified by a bright flare in X-rays, the event was given the name Swift J1644+57. The source was traced to a distant galaxy, so far away that its light took around 3.9 billion years to reach Earth.

    Jun Yang and his colleagues used the technique of very long baseline interferometry (VLBI), where a network of detectors separated by thousands of kilometres are combined into a single observatory, to make extremely high-precision measurements of the jet from Swift J1644+57.

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    Three years of extremely precise EVN measurements of the jet from Swift J1644+5734 show a very compact source with no signs of motion. Lower panel: false colour contour image of the jet (the ellipse in the lower left corner shows the size of an unresolved source). Upper panel: position measurement with dates. One microarcsecond is one 3 600 000 000th part of a degree. Image credit: EVN/JIVE/J. Yang.

    “Using the EVN telescope network we were able to measure the jet’s position to a precision of 10 microarcseconds. That corresponds to the angular extent of a 2-Euro coin on the Moon as seen from Earth. These are some of the sharpest measurements ever made by radio telescopes”, says Jun Yang.

    Thanks to the amazing precision possible with the network of radio telescopes, the scientists were able to search for signs of motion in the jet, despite its huge distance.

    “We looked for motion close to the light speed in the jet, so-called superluminal motion. Over our three years of observations such movement should have been clearly detectable. But our images reveal instead very compact and steady emission – there is no apparent motion”, continues Jun Yang.

    The results give important insights into what happens when a star is destroyed by a supermassive black hole, but also how newly launched jets behave in a pristine environment. Zsolt Paragi, Head of User Support at the Joint Institute for VLBI ERIC (JIVE) in Dwingeloo, Netherlands, and member of the team, explains why the jet appears to be so compact and stationary.

    “Newly formed relativistic ejecta decelerate quickly as they interact with the interstellar medium in the galaxy. Besides, earlier studies suggest we may be seeing the jet at a very small angle. That could contribute to the apparent compactness”, he says.

    The record-sharp and extremely sensitive observations would not have been possible without the full power of the many radio telescopes of different sizes which together make up the EVN, explains Tao An from the Shanghai Astronomical Observatory, P.R. China.

    “While the largest radio telescopes in the network contribute to the great sensitivity, the larger field of view provided by telescopes like the 25-m radio telescopes in Sheshan and Nanshan (China), and in Onsala (Sweden) played a crucial role in the investigation, allowing us to simultaneously observe Swift J1644+57 and a faint reference source,” he says.

    Swift J1644+57 is one of the first tidal disruption events to be studied in detail, and it won’t be the last.

    “Observations with the next generation of radio telescopes will tell us more about what actually happens when a star is eaten by a black hole – and how powerful jets form and evolve right next to black holes”, explains Stefanie Komossa, astronomer at the Max Planck Institute for Radio Astronomy in Bonn, Germany.

    “In the future, new, giant radio telescopes like FAST (Five hundred meter Aperture Spherical Telescope) and SKA (Square Kilometre Array) will allow us to make even more detailed observations of these extreme and exciting events,” concludes Jun Yang.

    See the full article here .

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    The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.

     
  • richardmitnick 11:36 am on July 2, 2016 Permalink | Reply
    Tags: , , Black Holes, ,   

    From Ethan Siegel: “Can Gravitational Waves Let Us Peek Inside A Black Hole?” 

    From Ethan Siegel

    Jul 2, 2016

    1
    Ilustration of a black hole and its surrounding, accelerating and infalling accretion disk. Image credit: NASA.

    Since LIGO first directly detected gravitational waves from merging black holes, scientists have taken a renewed interest in learning all about them.

    LSC LIGO Scientific Collaboration
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA
    VIRGO Collaboration bloc

    After all, with new data, a new technique and a new way of looking at the Universe, perhaps there are a whole slew of new discoveries that are now possible. One of a black hole’s fundamental properties, of course, is that nothing can exit its event horizon from inside, since the escape velocity in a black hole’s interior is greater than the speed of light. But perhaps that can be overcome? Patreon supporter Robert J. Hansen wants to know if there’s a way of viewing what’s inside:

    “If spacetime distortion can in effect boost the speed of light, is it possible for a passing gravitational wave to alter the event horizon of a black hole, giving us a way to observe the contents due to a temporary boosting of c?”

    Let’s take a look at the physics and find out!

    2
    In flat space, it’s easy to set up an infinite series of observers that all agree on the speed of light at different locations. Image credit: PixaBay user PixelAnarchy.

    You’ve no doubt heard that the speed of light in a vacuum, the universal constant of c, is a constant no matter what. In special relativity, this is strictly true; if your space is completely flat, there’s no way around this. You can set up, theoretically, an infinite series of observers, spaced a fixed distance apart, at rest with respect to one another. As a light wave goes by, the amount of time it takes each observer to see that light signal is fixed: the time it takes the light to go from 1 to 2 is the same as from 2 to 3, as 3 to 4, and from 99 to 100. There’s no disagreement and no ambiguity, and so everybody’s happy.

    3
    The spacetime in our local neighborhood, which is curved due to the gravitational influence of the Sun and other masses. Image Credit: T. Pyle/Caltech/MIT/LIGO Lab.

    But things get hairier once you allow space to be curved, which is the big difference between special and general relativity. If you try and place that same infinite series of observers a fixed distance apart and at rest with respect to one another, they’re going to fight. Not because of any interpersonal differences, but because their observations won’t agree with one another as to what constitutes a “fixed distance” or what “at rest” means. When the light signal passes by each observer, they each measure that signal’s speed to be c, just like you’d expect, but they can’t agree with one another as to what happens at the locations that aren’t their own. There’s no common standard of rulers and clocks that apply equally to all observers once you allow space to be curved.

    This is the same reason why, if you place an atomic clock at the bottom of a building and an identical atomic clock at the top, you’ll find that they run at slightly different rates. It’s not that one clock is flawed; it’s that the non-zero curvature of space makes it so that different observers disagree as to what makes a good “clock” at any location other than their own!

    4
    Light and ripples in space; as the light passes through non-flat space, it changes how an observer at any other location perceives the passage of time for the light. Image credit: European Gravitational Observatory, Lionel BRET/EUROLIOS.

    When a light signal passes through a region of curved space, a distant observer might see that signal as moving faster than c or slower than c, depending on how curved-or-flat the region they’re in and the region they’re observing are relative to one another. But is anything really moving faster or slower than c? No; what’s happening is we are often unable to measure what the speed of something at any location other than our own actually is. Einstein himself noted this in his 1920 book, Relativity: the special and general theory, where a translation (from German) reads:

    ” according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity […] cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity of propagation of light varies with position.

    Now, what about a passing gravitational wave? As it turns out, it will have an effect on all the space it passes through. Just as gravitational waves compress space in one direction while simultaneously stretching the perpendicular direction in an oscillatory fashion — a feature LIGO took advantage of to directly detect them — they will stretch and compress the event horizon of a black hole as well.


    Access mp4 video here .

    The waves that pass inside the black holes event horizon will, in fact, have their energy absorbed into the black hole itself; just as any light that fell in would add to the black hole’s mass (converting energy to mass via a less familiar form of Einstein’s famous equation, m = E/c2), so does gravitational radiation. But those that aren’t absorbed might distort the space around it, and the curved space itself — plus the changes in the curved space — would certainly affect the light-travel-time of anything surrounding it. Particles experience time differently in these gravitational fields; space looks longer-or-shorter depending on the physics of the waves passing through them; the shapes of both physical objects and non-physical geometric constructs indeed get distorted.

    5
    Any object or shape, physical or non-physical, would be distorted as gravitational waves passed through it. Image credit: NASA/Ames Research Center/C. Henze.

    But at no point does this mean that the space that was inside the event horizon ever travel to the outside. At no point would a particle from the interior ever find its way to the exterior. And at no instant could anyone receive information outside of the black hole about what was going on in the interior. The escape velocity of something right at the edge of the event horizon would still be c, and what you would call a “change in the speed of light” as an external observer (incapable of measuring speeds at any location other than your own) is more accurately described by a distortion in the curvature of space itself.

    6
    Any ripples in the fabric of space would affect a black hole’s event horizon as well, but nevertheless wouldn’t allow slower-than-light particles to escape from inside its event horizon. Image credit: Wikimedia Commons user Inductiveload.

    The space inside the event horizon might expand and/or contract as a gravitational wave passes through, but the best you could hope for is that a photon that otherwise would have fallen in might have a chance to not fall in. Gravitational waves don’t change the most fundamental, inescapable fact about black holes of all: nothing that’s already inside will ever get out.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

     
  • richardmitnick 4:01 pm on June 30, 2016 Permalink | Reply
    Tags: , , Black Holes, , ,   

    From U Chicago: “Simulations foresee hordes of colliding black holes in observatory’s future” 

    U Chicago bloc

    University of Chicago

    June 24, 2016
    Steve Koppes

    1
    New research predicts that LIGO will detect gravitational waves generated by many more merging black holes in coming years. Courtesy ofLIGO/A. Simonnet

    New calculations predict that the Laser Interferometer Gravitational wave Observatory (LIGO) will detect approximately 1,000 mergers of massive black holes annually once it achieves full sensitivity early next decade.

    LSC LIGO Scientific Collaboration
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA
    VIRGO Collaboration bloc

    The prediction, published online June 22 in the journal Nature, is based on computer simulations of more than a billion evolving binary stars. The simulations are based on state-of-the-art modeling of the physics involved, informed by the most recent astronomical and astrophysical observations.

    2
    Assoc. Prof. Daniel Holz. Photo by Robert Kozloff

    “The main thing we find is that what LIGO detected makes sense,” said Daniel Holz, associate professor in physics and astronomy at the University of Chicago and a co-author of the Nature paper. The simulations predict the formation of black-hole binary stars in a range of masses that includes the two already observed. As more LIGO data become available, Holz and his colleagues will be able to test their results more rigorously.

    The paper’s lead author, Krzysztof Belczynski of Warsaw University in Poland, said he hopes the results will surprise him, that they will expose flaws in the work. Their calculations show, for example, that once LIGO reaches full sensitivity, it will detect only one pair of colliding neutron stars for every 1,000 detections of the far more massive black-hole collisions.

    “Actually, I would love to be proven wrong on this issue. Then we will learn a lot,” Belczynski said.

    Forming big black holes

    The new Nature paper, which includes co-authors Tomasz Bulik of Warsaw University and Richard O’Shaughnessy of the Rochester Institute of Technology, describes the most likely black-hole formation scenario that generated the first LIGO gravitational-wave detection in September 2015. That detection confirmed a major prediction of Albert Einstein’s 1915 general theory of relativity.

    The paper is the most recent in a series of publications, topping a decade of analyses where Holz, Belczynski and their associates theorize that the universe has produced many black-hole binaries in the mass range that are close enough to Earth for LIGO to detect.

    “Here we simulate binary stars, how they evolve, turn into black holes and eventually get close enough to crash into each other and make gravitational waves that we would observe,” Holz said.

    The simulations show that the formation and evolution of a typical system of binary stars results in a merger of similar masses, and after similarly elapsed times, to the event that LIGO detected last September. These black hole mergers have masses ranging from 20 to 80 times more than the sun.

    LIGO will begin recording more gravitational-wave-generating events as the system becomes more sensitive and operates for longer periods of time. LIGO will go through successive upgrades over the coming years, and is expected to reach its design sensitivity by 2020. By then, the Nature study predicts that LIGO might be detecting more than 100 black hole collisions annually.

    LIGO has detected big black holes and big collisions, with a combined mass greater than 30 times that of the sun. These can only be formed out of big stars.

    “To make those you need to have low metallicity stars, which just means that these stars have to be relatively pristine,” Holz said. The Big Bang produced mainly hydrogen and helium, which eventually collapsed into stars.

    Forging metals

    As these stars burned they forged heavier elements, which astronomers call “metals.” Those stars with fewer metals lose less mass as they burn, resulting in the formation of more massive black holes when they die. That most likely happened approximately two billion years after the Big Bang, before the young universe had time to form significant quantities of heavy metals. Most of those black holes would have merged relatively quickly after their formation.

    LIGO would be unable to detect the ones that merged early and quickly. But if the binaries were formed in large enough numbers, a small fraction would survive for longer periods and would end up merging 11 billion years after the Big Bang (2.8 billion years ago), recently enough for LIGO to detect.

    “That’s in fact what we think happened,” Holz said. Statistically speaking, “it’s the most likely scenario.” He added, however, that the universe continues to produce binary stars in local, still pristine pockets of low metallicity that resemble conditions of the early universe.

    “In those pockets you can make these big stars, make the binaries, and then they’ll merge right away and we would detect those as well.”

    Belczynski, Holz and collaborators have based their simulations on what they regard as the best models available. They assume “isolated formation,” which involves two stars forming in a binary, evolving in tandem into black holes, and eventually merging with a burst of gravitational wave emission. A competing model is “dynamical formation,” which focuses on regions of the galaxy that contain a high density of independently evolving stars. Eventually, many of them will find each other and form binaries.

    “There are dynamical processes by which those black holes get closer and closer and eventually merge,” Holz said. Identifying which black holes merged under which scenario is difficult. One potential method would entail examining the black holes’ relative spins. Binary stars that evolved dynamically are expected to have randomly aligned spins; detecting a preference for aligned spins would be clear evidence in favor of the isolated evolutionary model.

    LIGO is not yet able to precisely measure black hole spin alignment, “but we’re starting to get there,” Holz said. “This study represents the first steps in the birth of the entirely new field of gravitational wave astronomy. We have been waiting for a century, and the future has finally arrived.”

    Citation: The first gravitational-wave source from the isolated evolution of two stars in the 40-100 solar mass range, by Krzysztof Belczynski, Daniel E. Holz, Tomasz Bulik, and Richard O’Shaughnessy,” Nature, Vol. 534, pp. 512-515, June 23, 2016, doi:10.1038/nature18322.

    Funding: National Science Centre Poland and National Science Foundation.

    See the full article here .

    Please help promote STEM in your local schools.

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    U Chicago Campus

    An intellectual destination

    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

     
  • richardmitnick 10:39 am on June 30, 2016 Permalink | Reply
    Tags: , , Black Holes, , ,   

    From Ethan Siegel: “Origin of LIGO’s merging black holes finally discovered!” 

    Ethan Siegel

    6.30.16

    The massive black holes that formed LIGO’s first event were a surprise, and then a mystery. Here’s the long-awaited solution!

    1
    A double black hole. Image credit: NASA, ESA and G. Bacon (STScI).

    “Black holes can bang against space-time as mallets on a drum and have a very characteristic song.” -Janna Levin

    In order to produce the gravitational wave signals that LIGO has seen so far, two extremely massive stars in a close, binary orbit must have both gone supernova an extremely long time ago. Over billions of years, those black holes spiraled into one another, as their orbits slowly decayed over the aeons, emitting small amounts of gravitational radiation at each step along the way. Finally, in the final fractions of a second, those ripples in spacetime were enough to vibrate our detectors here on Earth by less than a thousandth the width of a proton. That’s what it took to deliver our first directly detected gravitational wave signal, a century after Einstein’s relativity first predicted them.

    1
    The inspiral and merger of the first pair of black holes ever directly observed. Image credit: B. P. Abbott et al. (LIGO Scientific Collaboration and Virgo Collaboration).

    LSC LIGO Scientific Collaboration

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation

    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    VIRGO Collaboration bloc

    Before these gravitational waves were seen, all we had were theoretical models of what stellar-mass black holes might be. Contrary to the supermassive ones at the centers of galaxies, where we could measure the stars in orbit around them, the high-energy radiation emitted from the infalling matter, or the energy of the jets leaving them, all we had for these objects — the most common black holes in the Universe — was a story. We knew that stars that were massive enough would not only fuse hydrogen into helium during their main lifetime, and then turn into a red giant, fusing helium into carbon, but would go beyond that, heating up internally to achieve fusion reactions that less than 1% of stars will ever attain. Carbon fusion will begin, then oxygen, then silicon and sulphur and finally the core will be filled with iron, nickel and cobalt: elements too stable to fuse into heavier ones under normal conditions.

    Stars need to be many times the mass of the Sun — at least 8-to-10 but perhaps even more — to reach this stage. At this point, the inner core of the star, since there’s no more fusion occurring, runs out of its prime source of radiation, which was the only thing holding the nuclei inside up against gravitational collapse. So the core of the star collapses, catastrophically, and implodes, giving rise to a Type II Supernova.

    3
    Type IIb supernova

    The thing is, a star needs to initially be very massive to make a black hole. The overwhelming majority of the star that gives rise to a supernova gets blown off by the explosion; it’s only the innermost core that collapses. Most of the stars that do collapse give rise to neutron stars, just two or three times the mass of the Sun. And the stars that give rise to black holes — the ones 20, 40 or more times the mass of our Sun — were expected to lead to black holes maybe between 5 and 10 solar masses. Maybe the most massive ones would be even 15 or 20 times the mass of our Sun.

    But there’s a limit; high-mass stars tend to do something called quench star formation. The idea is that as a young star gets more and more massive, it burns brighter and hotter, and it not only prevents more matter from falling onto that star and growing it, it ionizes all the matter around it, and blows it off from the entire vicinity. In other words, it prevents all the other stars around it from growing larger; that’s what quench means.

    4
    The star forming region Sh 2–106, or S106 for short. A newly formed, ultra-massive star at the center, shrouded in dust, is responsible for carving the shape of this nebula. Image credit: NASA and ESA.

    So for two stars to have lived, died in supernovae, and created both a 36 and a 29 solar mass black hole means that something had to happen to avoid this scenario. What actually happens, we think, is more peculiar than you might have imagined altogether. The stars that gave rise to the black holes couldn’t have been formed too late (or with too many heavy elements in them) according to numerical models, which indicate that most likely they had only about 10% of the heavy elements (carbon, oxygen and iron, for example) found in our Sun.

    A new paper by Krzysztof Belczynski, Daniel E. Holz, Tomasz Bulik & Richard O’Shaughnessy, as well as a letter by J.J. Eldridge, suggest, based on simulations, that black hole binaries such as this arose in great numbers very early on in the Universe. Rather than from a Type II supernova, there are likely a whole class of binary black holes of ~30 solar masses (or slightly more) that arose from:

    massive binary star systems,
    between 40 and 100 solar masses to start,
    from when the Universe was only about ~2–3 billion years old,
    and that likely formed either in dwarf galaxies or on the outskirts of what would become a spiral galaxy: where there are fewer heavy elements.

    5
    Artist’s impression of two merging black holes, with accretion disks. The density and energy of the matter here is woefully insufficient to create gamma ray or X-ray bursts. Image credit: NASA / Dana Berry (Skyworks Digital).

    Over time, the radii of these stars increase as they heat up, making it easier to strip off their outer layers. The first one will go supernova as normal, but the second one will suffer a different fate. What happens in a binary system, rather than getting hotter and hotter and larger and larger, is that the outer layers get thrown off, via gravitational interaction, into the interstellar medium around them. The first black hole to form will also devour some of that material, but black holes are not very good eaters; they spit out most of what falls in. If both stars are massive and close enough, the second can lose its outer envelope. The core inside, then, simply contracts down and collapses without very much fanfare at all. In this way, we can get black holes without the standard, corresponding supernova explosions we know and recognize.

    In addition, the “common envelope” phase shrinks their mutual orbit, bringing them closer and closer to merger status. Despite many years of research, the quantitative answer of how much these orbits shrink by is still an open question with very large uncertainties. Nevertheless, the simulations of Belczynski’s team indicates that these black hole binaries very likely formed more than 10 billion years ago, and their inspirals and merger occurred just 1.3 billion years ago, with the light reaching us today.

    6
    Hubble space telescope of the merging star clusters at the heart of the Tarantula Nebula, the largest star-forming region known in the local group. Image credit: NASA, ESA, and E. Sabbi (ESA/STScI); Acknowledgment: R. O’Connell (University of Virginia) and the Wide Field Camera 3 Science Oversight Committee.

    There is another possibility they entertain, however: a much younger, massive cluster of stars — with higher mass binaries inside — could have created these black holes much more recently. Perhaps clusters like the one inside the massive Tarantula Nebula in our own local group give rise to black hole binaries, and, with stars up to 260 times the mass of our Sun in there, perhaps ~30–40 times the mass of our Sun isn’t even as large as these black holes get. Regardless of their origin, which we should be able to figure out as more statistics and detections come in, the next generation of gravitational wave observatories should be able to detect perhaps as many as 1,000 of these binary black hole mergers per year. We’re entering, for the first time, the era of direct black hole astronomy, courtesy of gravitational waves. What it means for astrophysics is more than most of us ever anticipated.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

     
  • richardmitnick 4:19 pm on June 28, 2016 Permalink | Reply
    Tags: , , Black Holes, , , ,   

    From Durham U: “Seeds of supermassive black holes could be revealed by gravitational waves 

    Durham U bloc

    Durham University

    27 June 2016
    No writer credit found


    Access mp4 video here .

    Gravitational waves captured by space-based detectors could help identify the origins of supermassive black holes, according to new computer simulations of the Universe.

    Scientists led by Durham University’s Institute for Computational Cosmology ran the huge cosmological simulations that can be used to predict the rate at which gravitational waves caused by collisions between the monster black holes might be detected.

    The amplitude and frequency of these waves could reveal the initial mass of the seeds from which the first black holes grew since they were formed 13 billion years ago and provide further clues about what caused them and where they formed, the researchers said.

    RAS National Astronomy Meeting

    The research is being presented today (Monday, June 27, 2016) at the Royal Astronomical Society’s National Astronomy Meeting in Nottingham, UK. It was funded by the Science and Technology Facilities Council, the European Research Council and the Belgian Interuniversity Attraction Poles Programme.

    The study combined simulations from the EAGLE project – which aims to create a realistic simulation of the known Universe inside a computer – with a model to calculate gravitational wave signals.

    Two detections of gravitational waves caused by collisions between supermassive black holes should be possible each year using space-based instruments such as the Evolved Laser Interferometer Space Antenna (eLISA) detector that is due to launch in 2034, the researchers said.

    ESA/eLISA
    ESA/eLISA

    In February the international LIGO and Virgo collaborations announced that they had detected gravitational waves for the first time using ground-based instruments and in June reported a second detection.

    LSC LIGO Scientific Collaboration
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation

    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Supermassive black holes

    As eLISA will be in space – and will be at least 250,000 times larger than detectors on Earth – it should be able to detect the much lower frequency gravitational waves caused by collisions between supermassive black holes that are up to a million times the mass of our sun.

    Current theories suggest that the seeds of these black holes were the result of either the growth and collapse of the first generation of stars in the Universe; collisions between stars in dense stellar clusters; or the direct collapse of extremely massive stars in the early Universe.

    As each of these theories predicts different initial masses for the seeds of supermassive black hole seeds, the collisions would produce different gravitational wave signals.

    This means that the potential detections by eLISA could help pinpoint the mechanism that helped create supermassive black holes and when in the history of the Universe they formed.

    Gravitational waves

    Lead author Jaime Salcido, PhD student in Durham University’s Institute for Computational Cosmology, said: “Understanding more about gravitational waves means that we can study the Universe in an entirely different way.

    “These waves are caused by massive collisions between objects with a mass far greater than our sun.

    “By combining the detection of gravitational waves with simulations we could ultimately work out when and how the first seeds of supermassive black holes formed.”

    Co- author Professor Richard Bower, of Durham University’s Institute for Computational Cosmology, added: “Black holes are fundamental to galaxy formation and are thought to sit at the centre of most galaxies, including our very own Milky Way.

    “Discovering how they came to be where they are is one of the unsolved problems of cosmology and astronomy.

    “Our research has shown how space based detectors will provide new insights into the nature of supermassive black holes.”

    Detecting gravitational waves in space

    Gravitational waves were first predicted 100 years ago by Albert Einstein as part of his Theory of General Relativity.

    The waves are concentric ripples caused by violent events in the Universe that squeeze and stretch the fabric of space time but most are so weak they cannot be detected.

    LIGO detected gravitational waves using ground-based instruments, called interferometers, that use laser beams to pick up subtle disturbances caused by the waves.

    eLISA will work in a similar way, detecting the small changes in distances between three satellites that will orbit the sun in a triangular pattern connected by beams from lasers in each satellite.

    In June it was reported that the LISA Pathfinder, the forerunner to eLISA, had successfully demonstrated the technology that opens the door to the development of a large space observatory capable of detecting gravitational waves in space.

    ESA/LISA Pathfinder
    ESA/LISA Pathfinder

    • Durham’s researchers will show how they use supercomputer simulations to test how galactic ingredients and violent events combine to shape the life history of galaxies when they exhibit at the Royal Society Summer Science Exhibition in London from 4 to 10 July, 2016.

    See the full article here .

    Please help promote STEM in your local schools.

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    Durham U campus

    Durham University is distinctive – a residential collegiate university with long traditions and modern values. We seek the highest distinction in research and scholarship and are committed to excellence in all aspects of education and transmission of knowledge. Our research and scholarship affect every continent. We are proud to be an international scholarly community which reflects the ambitions of cultures from around the world. We promote individual participation, providing a rounded education in which students, staff and alumni gain both the academic and the personal skills required to flourish.

     
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