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  • richardmitnick 8:07 am on July 23, 2015 Permalink | Reply
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    From RAS: “Treasure hunting in archive data reveals clues about black holes’ diet” 

    Royal Astronomical Society

    Royal Astronomical Society

    23 July 2015

    Media contact
    Dr Hannelore Hämmerle
    Max-Planck-Institut für extraterrestrische Physik
    Tel: +49 (0)89 30000 3980

    Science contact
    Dr Andrea Merloni
    Max-Planck-Institut für extraterrestrische Physik
    Tel: +49 (0)89 30000-3893

    A snapshot image from a computer simulation of a star disrupted by a supermassive black hole. The red-orange plumes show the debris of the star after its passage near the black hole (located close to the bottom left corner of the image). About half of the disrupted star moves in elliptical orbits around the black hole and forms an accretion disc which eventually shines brightly in optical and X-ray wavelengths. Credit: J. Guillochon (Harvard University) and E. Ramirez-Ruiz (University of California).

    Using archival data from the Sloan Digital Sky Survey [SDSS], and the XMM-Newton and Chandra X-ray telescopes, a team of astronomers have discovered a gigantic black hole, which is probably destroying and devouring a massive star in its vicinity.

    Sloan Digital Sky Survey Telescope
    SDSS telescope at Apache Point, NM, USA

    ESA XMM Newton

    NASA Chandra Telescope

    With a mass of 100 million times more than our Sun, this is the largest black hole caught in this act so far. The results of this study are published in a paper in the journal Monthly Notices of the Royal Astronomical Society.

    Andrea Merloni and members of his team, from the Max-Planck Institute for Extraterrestrial Physics (MPE) in Garching, near Munich, were exploring the huge archive of the Sloan Digital Sky Survey (SDSS) in preparation for a future X-ray satellite mission. The SDSS has been observing a large fraction of the night sky with its optical telescope. In addition, spectra (where light is dispersed across wavelengths, allowing astronomers to deduce properties like composition and temperature) have been taken of distant galaxies and black holes.

    These plots show two SDSS spectra of the object; the different luminosities as a function of wavelength between the two epochs are clearly visible. In particular, the red dashed vertical lines show the hydrogen Balmer lines which dramatically change their shape: in the red spectrum they are much broader, which provides a “fingerprint” signature of the accretion onto a central black hole. Credit: © SDSS/MPE.

    For a variety of reasons, the spectra of some objects were taken more than once. And when the team was looking at one of the objects with multiple spectra, they were struck by an extraordinary change in one of the objects under study, with the catalogue number SDSS J0159+0033, a galaxy in the constellation of Cetus. The huge distance to the galaxy means that we see it as it was 3.5 billion years ago.

    “Usually distant galaxies do not change significantly over an astronomer’s lifetime, i.e. on a timescale of years or decades,” explains Andrea Merloni, “but this one showed a dramatic variation of its spectrum, as if the central black hole had switched on and off.”

    This happened between 1998 and 2005, but nobody had noticed the odd behaviour of this galaxy until late last year, when two groups of scientists preparing the next (fourth) generation of SDSS surveys independently stumbled across these data.

    Luckily enough, the two flagship X-ray observatories, the ESA-led XMM-Newton and the NASA-led Chandra took snapshots of the same area of the sky close in time to the peak of the flare, and again about ten years later. This gave the astronomers unique information about the high-energy emission that reveals how material is processed in the immediate vicinity of the central black hole.

    Gigantic black holes are at home in the nuclei of large galaxies all around us. Most astronomers believe that they grew to the enormous sizes that we can observe today by feeding mostly on interstellar gas from their surroundings, which is unable to escape the immense gravitational pull. Such a process takes place over a very long time (tens to hundreds of millions of years), and is capable of turning a small black hole created in the explosion of a heavy star into the super-heavyweight monsters that lurk at the centre of galaxies.

    However, galaxies also contain a huge number of stars. Some unlucky ones may happen to pass too close to the central black hole, where they are destroyed and eventually swallowed by the black hole. If this is compact enough, the strong, tidal gravitational forces tear the star apart in a spectacular way. Subsequently bits and pieces swirl into the black hole and thus produce huge flares of radiation that can be as luminous as all of the rest of the stars in the host galaxy for a period of a few months to a year. These rare events are called Tidal Disruption Flares (TDF).

    Merloni and his collaborators quite quickly realised that ‘their’ flare matched almost perfectly all the expectations of this model. Moreover, because of the serendipitous nature of the discovery, they realised that this was an even more peculiar system than those which had been found through active searches until now. With an estimated mass of 100 million solar masses, this is the biggest black hole caught in the act of star-tearing so far.

    However, the sheer size of the system is not the only intriguing aspect of this particular flare; it is also the first one for which scientists can assume with some degree of certainty that the black hole was on a more standard ‘gas diet’ very recently (a few tens of thousands of years). This is an important clue to finding out which sort of food black holes mostly live on.

    Download video here: https://www.youtube.com/watch?feature=player_embedded&v=hggUYcmSjlI
    This computer simulation of the disruption of a star by a black hole shows the formation of an accretion disk of stellar material spiralling into the black hole. This sequence shows an early stage in the formation of the disk. The stellar material is coloured according to its temperature, with red being colder and purple hotter. Credit: J. Guillochon and E. Ramirez Ruiz

    “Louis Pasteur said: ‘Chance favours the prepared mind’ – but in our case, nobody was really prepared,” marvels Merloni. “We could have discovered this unique object already ten years ago, but people did not know where to look. It is quite common in astronomy that progress in our understanding of the cosmos is helped by serendipitous discoveries. And now we have a better idea of how to find more such events, and future instruments will greatly expand our reach.”

    In less than two years’ time a new powerful X-ray telescope eROSITA, which is currently being built at MPE, will be put into orbit on the Russian-German SRG satellite.


    It will scan the entire sky with the right cadence and sensitivity needed to discover hundreds of new tidal disruption flares. Big optical telescopes are also being designed and built with the goal of monitoring the variable sky, and will greatly contribute to solving the mystery of black hole eating habits. Astronomers will have to be prepared to catch these dramatic last acts of a star’s life. But however prepared they’ll be, the sky will be full of new surprises.

    Further information

    The new work appears in A tidal disruption flare in a massive galaxy? Implications for the fuelling mechanisms of nuclear black holes, A. Merloni, T. Dwelly, M. Salvato, A. Georgakakis, J. Greiner, M. Krumpe, K. Nandra, G. Ponti, A. Rau, Monthly Notices of the Royal Astronomical Society, Oxford University Press.
    The other group, who independently discovered the strange light curve of this object, was Stephanie Lamassa (Yale) and her collaborators. They were the fastest to alert the community about this object, but did not explore the stellar disruption interpretation for this event.
    Tidal Disruption Flares are very rare, with perhaps one occurring every few tens of thousands of year in any given galaxy. In addition, because they do not last very long, they are very hard to find. Only about twenty of them have been studied so far, but with the advent of larger telescopes designed to survey large areas of the sky in a short time, more and more dedicated searches are being carried out, and the pace of discovery is rapidly increasing.

    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 1:19 pm on July 20, 2015 Permalink | Reply
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    From NOVA: “Black Holes Could Turn You Into a Hologram, and You Wouldn’t Even Notice” 



    01 Jul 2015
    Tim De Chant

    Black holes may not have event horizons, but fuzzy surfaces.

    Few things are as mysterious as black holes. Except, of course, what would happen to you if you fell into one.

    Physicists have been debating what might happen to anyone unfortunate enough to slip toward the singularity, and so far, they’ve come up with approximately 2.5 ways you might die, from being stretched like spaghetti to burnt to a crisp.

    The fiery hypothesis is a product of Stephen Hawking’s firewall theory, which also says that black holes eventually evaporate, destroying everything inside. But this violates a fundamental principle of physics—that information cannot be destroyed—so other physicists, including Samir Mathur, have been searching for ways to address that error.

    Here’s Marika Taylor, writing for The Conversation:

    The general relativity description of black holes suggests that once you go past the event horizon, the surface of a black hole, you can go deeper and deeper. As you do, space and time become warped until they reach a point called the “singularity” at which point the laws of physics cease to exist. (Although in reality, you would die pretty early on on this journey as you are pulled apart by intense tidal forces).

    In Mathur’s universe, however, there is nothing beyond the fuzzy event horizon.

    Mathur’s take on black holes suggests that they aren’t surrounded by a point-of-no-return event horizon or a firewall that would incinerate you, but a fuzzball with small variations that maintain a record of the information that fell into it. What does touch the fuzzball is converted into a hologram. It’s not a perfect copy, but a doppelgänger of sorts.

    Perhaps more bizarrely, you even wouldn’t be aware that of the transformation. Say you were to be sucked toward a black hole. At the point where you’d normally hit the event horizon, Mathur says, you’d instead touch the fuzzy surface. But instead of noticing anything, the fuzzy surface would appear like any other part of space immediately around you. Everything would seem the same as it was, except that you’d be a hologram.

    See the full article here.

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    NOVA is the highest rated science series on television and the most watched documentary series on public television. It is also one of television’s most acclaimed series, having won every major television award, most of them many times over.

  • richardmitnick 3:12 pm on July 10, 2015 Permalink | Reply
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    Keck’s Take on the Black Hole in CID-947″ 

    Keck Observatory

    Keck Observatory

    The subject was previously covered in an earlier post, “From Chandra: ‘A Precocious Black Hole'”. But the writers at Keck spent a lot of time on this, and their views are always excellent, so it is worth seeing their work.

    Keck Observatory

    “Gigantic, Early Black Hole Could Upend Evolutionary Theory”

    July 9, 2015

    Benny Trakhtenbrot
    ETH Zürich
    Institute for Astronomy, Switzerland
    +41 (0)44-632-4213

    Steve Jefferson
    W. M. Keck Observatory

    In this illustration a black hole emits part of the accreted matter in the form of energetic radiation (blue), without slowing down star formation within the host galaxy (purple regions). Credit: M. Helfenbein, Yale University / OPAC

    An international team of astrophysicists led by Benny Trakhtenbrot, a researcher at ETH Zurich’s Institute for Astronomy, discovered a gigantic black hole in an otherwise normal galaxy, using W. M. Keck Observatory’s 10-meter, Keck I telescope in Hawaii. The team, conducting a fairly routine hunt for ancient, massive black holes, was surprised to find one with a mass of more than 7 billion times our Sun making it among the most massive black holes ever discovered. And because the galaxy it was discovered in was fairly typical in size, the study calls into question previous assumptions on the development of galaxies. Their findings are being published today in the journal Science.

    The data, collected with Keck Observatory’s newest instrument called MOSFIRE, revealed a giant black hole in a galaxy called CID-947 that was 11 billion light years away.

    Keck MOSFIRE

    The incredible sensitivity of MOSFIRE coupled to the world’s largest optical/infrared telescope meant the scientists were able to observe and characterize this black hole as it was when the Universe was less than two billion years old, just 14 percent of its current age (almost 14 billion years have passed since the Big Bang).

    Even more surprising than the black hole’s record mass, was the relatively ordinary mass of the galaxy that contained it.

    Most galaxies host black holes with with masses less than one percent of the galaxy. In CID-947, the black hole mass is 10 percent that of its host galaxy. Because of this remarkable disparity, the team deduced this black hole grew so quickly the host galaxy was not able to keep pace, calling into question previous thinking on the co-evolution of galaxies and their central black holes.

    “The measurements of CID-947 correspond to the mass of a typical galaxy,” Trakhtenbrot said. “We therefore have a gigantic black hole within a normal size galaxy. The result was so surprising, two of the astronomers had to verify the galaxy mass independently. Both came to the same conclusion.”

    “Black holes are objects that possess such a strong gravitational force that nothing – not even light – can escape,” said Professor Meg Urry of Yale University, co-author of the study. ” Einstein’s theory of relativity describes how they bend space-time itself. The existence of black holes can be proven because matter is greatly accelerated by the gravitational force and thus emits particularly high-energy radiation.”

    Until now, observations have indicated that the greater the number of stars present in the host galaxy, the bigger the black hole. “This is true for the local Universe, which merely reflects the situation in the Universe’s recent past,” Urry said.

    Furthermore, previous studies suggest the radiation emitted during the growth of the black hole controlled, or even stopped, the creation of stars as the released energy heated up the gas. This cumulative evidence led scientists to assume the growth of black holes and the formation of stars go hand-in-hand.

    The latest results, however, suggest that these processes work differently, at least in the early Universe.

    The distant young black hole observed by Trakhtenbrot, Urry and their colleagues had roughly 10 times less mass than its galaxy. In today’s local Universe, black holes typically reach a mass of 0.2 to 0.5 percent of their host galaxy’s mass. “That means this black hole grew much more efficiently than its galaxy – contradicting the models that predicted a hand-in-hand development,” he said.

    The researchers also concluded stars were still forming even though the black hole had reached the end of its growth. Contrary to previous assumptions, the energy and gas flow propelled by the black hole did not stop the creation of stars.

    “From the available Chandra data for the source, we also concluded that the black hole has a very low accretion rate, and is therefore reached the end of its growth. On the other had, other data suggests that stars were still forming throughout the host galaxy,” Trakhtenbrot said.

    NASA Chandra Telescope

    The galaxy could continue to grow in the future, but the relationship between the mass of the black hole and that of the stars would remain unusually large. The researchers believe CID-947 could be a precursor of the most extreme, massive systems that we observe in today’s local Universe, such as the galaxy NGC 1277 in the constellation of Perseus, some 220 million light years away from our Milky Way.

    MOSFIRE (Multi-Object Spectrograph for Infrared Exploration) is a highly-efficient instrument that can take images or up to 46 simultaneous spectra. Using a sensitive state-of-the-art detector and electronics system, MOSFIRE obtains observations fainter than any other near infrared spectrograph. MOSFIRE is an excellent tool for studying complex star or galaxy fields, including distant galaxies in the early Universe, as well as star clusters in our own Galaxy. MOSFIRE was made possible by funding provided by the National Science Foundation and astronomy benefactors Gordon and Betty Moore.

    See the full article here.

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    To advance the frontiers of astronomy and share our discoveries with the world.

    The W. M. Keck Observatory operates the largest, most scientifically productive telescopes on Earth. The two, 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Island of Hawaii feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrometer and world-leading laser guide star adaptive optics systems. Keck Observatory is a private 501(c) 3 non-profit organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

    Today Keck Observatory is supported by both public funding sources and private philanthropy. As a 501(c)3, the organization is managed by the California Association for Research in Astronomy (CARA), whose Board of Directors includes representatives from the California Institute of Technology and the University of California, with liaisons to the board from NASA and the Keck Foundation.
    Keck UCal

    Keck NASA

    Keck Caltech

  • richardmitnick 3:08 pm on July 9, 2015 Permalink | Reply
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    From Chandra: “A Precocious Black Hole” 

    NASA Chandra

    July 9, 2015

    Megan Watzke
    Chandra X-ray Center, Cambridge, Mass.

    Credit: Illustration: M. Helfenbein, Yale University / OPAC

    Researchers have discovered a black hole that grew much more quickly than its host galaxy. The discovery calls into question previous assumptions on the development of galaxies.

    The black hole was originally discovered using NASA’s Hubble Space Telescope, and was then detected in the Sloan Digital Sky Survey and by ESA’s XMM-Newton and NASA’s Chandra X-ray Observatory.

    Benny Trakhtenbrot, from ETH Zurich’s Institute for Astronomy, and an international team of astrophysicists, performed a follow-up observation of this black hole using the 10 meter Keck telescope in Hawaii and were surprised by the results. The data, collected with a new instrument, revealed a giant black hole in an otherwise normal, distant galaxy, called CID-947. Because its light had to travel a very long distance, the scientists were observing it at a period when the universe was less than two billion years old, just 14 percent of its current age (almost 14 billion years have passed since the Big Bang).

    An analysis of the data collected in Hawaii revealed that the black hole in CID-947, with nearly 7 billion solar masses, is among the most massive black holes discovered up to now. What surprised researchers in particular was not the black hole’s record mass, but rather the galaxy’s mass. “The measurements correspond to the mass of a typical galaxy,” says Trakhtenbrot, a postdoctoral fellow working within the Extragalactic Astrophysics research group of Professor Marcella Carollo. “We therefore have a gigantic black hole within a normal size galaxy.” The result was so surprising that two of the astronomers, including Hyewon Suh from the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, MA, had to verify the galaxy mass independently. Both came to the same conclusion. The team reports its findings in the current issue of the scientific journal Science.

    Was anything different in the early Universe?

    Most galaxies, including our Milky Way, have a black hole at their center that holds millions to billions of solar masses. “Black holes are objects that possess such a strong gravitational force that nothing – not even light – can escape. Einstein’s theory of relativity describes how they bend space-time itself,” explains ETH professor Kevin Schawinski, co-author of the new study. The existence of black holes can be proven because matter is greatly accelerated by the gravitational force and thus emits particularly high-energy radiation.

    Until now, observations have indicated that the greater the number of stars present in the host galaxy, the bigger the black hole. “This is true for the local universe, which merely reflects the situation in the Universe’s recent past,” says Trakhtenbrot. This link, along with other evidence, led the scientists to assume that the growth of black holes and the formation of stars go hand-in-hand. This is quite reasonable, if a common reservoir of cold gas was responsible for the formation of the stars and the ‘feeding’ of the black hole at the galaxy’s center, says Trakhtenbrot. Furthermore, previous studies suggested that the radiation emitted during the growth of the black hole controlled, or even stopped the creation of stars, as the released energy heated up the gas. The latest results, however, suggest that these processes work differently, at least in the early universe.

    Star formation continues

    The distant young black hole observed by Trakhtenbrot and his colleagues weighs about 10% of its host galaxy’s mass. In today’s local universe, black holes typically reach a mass of 0.2% to 0.5% of their host galaxy’s mass. “That means this black hole grew much more efficiently than its galaxy – contradicting the models that predicted a hand-in-hand development,” explains the ETH researcher. From the available Chandra data for this source, the researchers also concluded that the black hole had reached the end of its growth. However, other data suggests stars were still forming throughout the host galaxy. Contrary to previous assumptions, the energy and gas flow, propelled by the black hole, did not stop the creation of stars.

    The galaxy could continue to grow in the future, but the relationship between the mass of the black hole and that of the stars would remain unusually large. The researchers believe that CID-947 could thus be a precursor of the most extreme, massive systems that we observe in today’s local universe, such as the galaxy NGC 1277 in the constellation of Perseus, some 220 million light years away from our Milky Way. They hope to gain further insight into the links between the black hole and the host galaxy, through observations with the Alma radio telescope in Chile.

    The black hole was selected from a 2011 paper published by Francesca Civano, from Yale University in New Haven, CT and CfA, as part of the Chandra Cosmic Evolution Survey. The full list of authors of the Science paper are Benny Trakhtenbrot ; Megan Urry from Yale University in New Haven, CT; Francesca Civano; David Rosario from the Max Planck Institute for Astrophysics in Garching, Germany; Martin Elvis from CfA; Kevin Schawinski; Hyewon Suh; Angela Bongiorno from the National Institute for Astrophysics in Rome, Italy and Brooke D. Simmons from Oxford University in the UK.

    NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for the agency’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra’s science and flight operations.
    An interactive image, a podcast, and a video about the findings are available at:


    For more Chandra images, multimedia and related materials, visit:


    See the full article here.

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    NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

  • richardmitnick 11:41 am on June 10, 2015 Permalink | Reply
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    From NYT: “An Earthling’s Guide to Black Holes” 

    New York Times

    The New York Times

    JUNE 8, 2015

    Welcome, earthlings, to the place of no return — a region in space where the gravitational pull is so strong, not even light can escape it. This is a black hole.

    It’s ok to feel lost here. Even [Albert] Einstein — whose Theory of General Relativity made it possible to conceive of such a place — thought the concept was too bizarre to exist. But Einstein was wrong, and here you are.

    You shouldn’t be here. You will surely get pulled in. But fear not dear Earthling, this is just your mind thinking. It has taken your brain millions of years to get here. So let’s get started.

    Bright flares are visible near the event horizon of a super-massive black hole at the center of the Milky Way. Credit NASA/CXC, via MIT, via F.K.Baganoff

    The black hole is a hungry beast.

    It swallows up everything too close, too slow or too small to fight its gravitational force — even light. With every planet, gas, star or bit of mass consumed, the black hole grows.

    At the edge of a black hole, its event horizon, is the point of no return. Stay far away from the event horizon, because that’s where the hole pulls in light. And nothing is faster than light. At the event horizon, everything enters the black hole.

    The brightest white spot in the middle is the very center of the Milky Way galaxy, which also marks the site of a supermassive black hole. Credit NASA/JPL-Caltech

    Pretty much everything we understand about how the universe works, depends on the black hole.

    Someone is wrong, or we have to admit that earthlings still aren’t equipped to understand the universe. The firewall paradox calls to question the most definitive theories of science. Albert Einstein, Joseph Polchinski or Stephen Hawking, or none, everything we know about the universe could change if we could know for certain what happens to information inside a black hole.

    An interpretation of a black hole, created for an educational video game. Credit Denver Museum of Nature and Science

    If you fell into a black hole, it’s not clear how you would die.

    Will gravity rip you apart and crush you into the black hole’s core? Or will a firewall of energy sizzle you into oblivion? Could some essence of you ever emerge from a black hole? First posited by a group of theorists including Donald Marolf, Ahmed Almheiri, James Sully and Joseph Polchinski in March 2012, the question of how you would die inside a black hole is probably the biggest debate in physics right now. It’s called the firewall paradox.

    Based on the mathematics in Einstein’s 1915 General Theory of Relativity, you would fall through the event horizon unscathed before gravity’s force pulled you into a noodle and ultimately crammed you into singularity, the black hole’s infinitely dense core.

    But Dr. Polchinski and his team pitted Einstein against quantum theory, which posited that the event horizon would become a blazing firewall of energy that would torch your body to smithereens.

    Keep both theories, the physicist Stephen Hawking said in January 2014. Black holes aren’t what we thought they were. There is no event horizon, and there is no singularity. They’re just different.

    According to Dr. Hawking, at the edge of a black hole, the fourth dimension known as space-time fluctuates like weather, making the crisp edge we assume impossible. Instead, Dr. Hawking’s “apparent horizon” would be like a purgatory for light rays attempting to escape a black hole, slowly dissolving and moving inward, but never being pulled into singularity. The event horizon, he says, remains the same, or even shrinks as a black hole slowly leaks energy. Suspended in the apparent zone, you would scramble and leak out into the cosmos as “Hawking radiation.”

    Galaxy NGC 1275. Credit NASA

    Black holes can sing.

    In 2003, an international team led by the X-ray astronomer Andrew Fabian discovered the longest, oldest, lowest note in the universe — a black hole’s song — using NASA’s Chandra X-ray Observatory.

    NASA Chandra Telescope

    Although it is too low and deep for humans to hear, the B flat note, 57 octaves below middle C, appeared as sound waves that moved out from explosive events at the edge of a supermassive black hole in the galaxy NGC 1275.

    NGC 1275 per NASA/ESA Hubble

    The notes stayed in the galaxy and never reached us, but we couldn’t have heard them anyway. The lowest note the human ear can detect has an oscillation period of one-twentieth of a second. This B flat’s period was 10 million years.

    The “songs” of black holes may be behind a declining birth rate of stars in the universe. In clusters of galaxies such as Perseus, the home of NGC 1275, the energy these notes carry is thought to keep the gases too hot to condense and form stars.

    A big galaxy gobbles a tiny one. Credit Swinburne University of Technology/Reuters

    Meet the management: Black holes may control the size of a galaxy.

    Playing music that keeps the intergalactic clusters too hot for stars might not be the only way black holes help maintain galaxies.

    Astronomers think that the energy that forms when galactic masses swirl and heat up around a black hole shoots out in X-ray beams that fuel quasars, supermassive black holes that are actively chomping down gas at the centers of distant galaxies.

    The Milky Way as visible from the desert southwest of Cairo. Credit Amr Abdallah Dalsh/Reuters

    Astronomers have evidence for black holes in nearly every galaxy in the universe.

    Although no black hole is close enough to Earth to pull the planet into its depths, there are so many black holes in the universe that counting them is impossible. Nearly every galaxy — our own Milky Way as well as the 100 billion or so other galaxies visible from Earth — shows signs of a black hole.

    Of the billions of stars in the Milky Way, about one in every thousand new stars is massive enough to become a black hole. Our sun isn’t. But a star 25 times heavier is. Stellar-mass black holes result from the death of these stars, and can exist anywhere in the galaxy.

    Supermassive black holes — a million to a billion times more massive than our sun — exist only in the center of a galaxy. At the center of the Milky Way, 26,000 light-years from Earth, scientists are hoping to make an image of Sagittarius A*, which is believed to be our own supermassive black hole, with the mass of four million suns. How supermassive black holes form is still a mystery.

    Sagittarius A* from NASA’s Chandra X-Ray Observatory

    Black holes are stellar tombstones.

    It wasn’t a nuclear bomb, and it wasn’t terrestrial. On July 2, 1967, a network of satellites recorded an explosion of gamma rays coming from outer space. In retrospect, this was one of the first indications that black holes are real. Today, scientists believe that the gamma ray burst is the final breath of a dying star and the birth of a stellar-mass black hole.

    The dramatic transformation starts when a massive star runs out of fuel to power itself. As the star begins to collapse, it explodes. The star’s outer layers spew out into space, but the inside implodes, becoming denser and denser, until there is too much matter in too little space. The core succumbs to its own gravitational pull and collapses into itself, in extreme cases forming a black hole.

    Theoretically, if you shrunk any mass down into a certain amount of space, it could become a black hole. Our earth would be one if you tried to cram the earth into a pea.

    NASA’s Hubble Space Telescope captured a high energy blast, likely a black hole eating, at the center of a galaxy. Credit NASA

    ‘A black hole has no hair.’

    On March 28, 2011, astronomers detected a long gamma ray burst coming from the center of a galaxy four billion light-years away. This was the first time humans observed what might have been a dormant black hole eating a star.

    No matter what a black hole eats — a star, a donkey, an iPhone, your grammar teacher — it’s all the same. As the physicist John Archibald Wheeler put it, “A black hole has no hair,” meaning that a black hole remembers only the mass, spin and charge of its dinner.

    The more a black hole eats, the more it grows. In 2011, scientists discovered one of the biggest black holes ever, more than 300 million light-years away. It weighs enough to have gobbled up 21 billion suns. Scientists want to know if the biggest black holes are the result of two holes merging or one hole eating a lot. But scientists don’t know how they grew so large.

    The Event Horizon Telescope is attempting to get the first ever portrait of the hungry monster at the center of our galaxy. Credit James D. Lowenthal/Smith College Astronomy Department

    To find the darkness, follow the light.

    Because light can’t escape a black hole, seeing what’s inside it is impossible. Getting a picture of a black hole’s edge is difficult, and getting a clear picture is an event.

    Actually, it has never been done. Scientists suspect black holes when their tools detect high-energy radio waves, such as those that may result from a collapsing star, gamma ray burst, supernova or the energy an object might release before reaching the black hole’s event horizon. Generally, if there is a lot of energy with a massive core at the center of a galaxy, the core is probably a black hole.

    The Event Horizon Telescope, the one Sheperd Doeleman and his colleagues used to try to photograph Sagittarius A* and M87, another black hole, featured a cast of more than 100 scientists on three continents and one very important crystal used to calibrate atomic clocks. The scientists staked out seven telescopes atop six mountains, synchronized time, pointed their discs at the sky and waited. For the first time ever, scientists may have seen a rough image of a black hole’s event horizon.

    An artist’s conception of stars moving in the central regions of a giant elliptical galaxy that harbors a black hole. Credit Lynette Cook/Gemini Observatory, via Nature, via Associated Press

    A black hole is not forever.

    As Hawking radiation leaks out into the universe, quantum effects suggest that a black hole will evaporate — eventually. It would take many times the age of the universe for a black hole to fully evaporate.

    Dr. Hawking, like Einstein, at first did not believe his own theory. But the numbers were right. Physicists now view his result as the backbone for whatever future theory will bring together gravity and quantum theory.

    This magnet is part of The Large Hadron Collider, the world’s largest and most powerful particle accelerator. [at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland. ] Credit Fabrice Coffrini/Agence France-Presse — Getty Images

    A giant magnet in Europe will not destroy the planet.

    Before the European Organization for Nuclear Research fired up the Large Hadron Collider in 2008, critics worried that smashing together protons in a 17-mile ring underground would create a black hole that would swallow the earth.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    Worriers echoed apocalyptic cries about Brookhaven National Laboratory’s Relativistic Heavy Ion Collider that the center’s scientists had squelched nearly 10 years earlier.

    BNL RHIC Campus
    RHIC at BNL

    According to their calculations, ultrahigh-energy cosmic rays already penetrated the earth’s atmosphere and predicted about 100 tiny black holes on earth every year. If tiny black holes were a problem, Earth would have already collapsed into infinity:

    Still, in June 2008, a safety review proclaimed the L.H.C. was indeed safe. Experiments commenced, the Higgs boson was found, and the earth survived after all.

    In the search for the smallest particles in the universe, the consequential mini black holes that scientists might create in contained underground tubes would let them observe general relativity and quantum mechanics in action and may open the door to solving the firewall paradox.

    See the full article here.

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  • richardmitnick 10:05 am on April 21, 2015 Permalink | Reply
    Tags: , , Black Holes,   

    From Nature: “3D simulations of colliding black holes hailed as most realistic yet” 

    Nature Mag

    20 April 2015
    Ron Cowen

    In-spiral and merger of binary black holes
    Simulations: S. Shapiro, R. Gold, V. Paschalidis, M. Ruiz, Z. Etienne & H. Pfeiffer. Movie: S. Shapiro, S. Connelly, A. Khan and L. Kong.

    When astronomers try to simulate colliding giant black holes, they usually rely on simplified approximations to model the swirling disks of matter that surround and fuel these gravitational monsters. Researchers now report that, for the first time, they have simulated the collision of two supermassive black holes using a full-blown treatment of [Albert] Einstein’s general theory of relativity, allowing a 3D portrayal of these disks of magnetized matter.

    The simulations more accurately describe the radiation that might be detected from such mergers. This includes electromagnetic radiation blasted into space and ripples in space-time known as gravitational waves. Stuart Shapiro of the University of Illinois at Urbana-Champaign presented movies of the simulations at a meeting of the American Physical Society in Baltimore, Maryland, on 13 April. His team had described elements of the study last November, in Physical Review D.

    Gravitational waves generated by black hole merger Simulations: S. Shapiro, R. Gold, V. Paschalidis, M. Ruiz, Z. Etienne & H. Pfeiffer. Movie: S. Shapiro, S. Connelly, A. Khan and L. Kong.

    “As a technical achievement, there’s no doubt that this is a giant step forward,” says astronomer Cole Miller of the University of Maryland in College Park, who was not part of the study.

    Collision course

    For the simulations, Shapiro’s team developed a mathematical model to couple Einstein’s equations (which describe the gravitational field around a black hole) with equations that govern the motion of matter moving close to the speed of light in a magnetic field.

    The simulations may take on added significance, says Shapiro, because recent observations hint that a black hole weighing as much as ten billion Suns might be set to collide with a similarly massive partner in a mere seven years.

    Analysing data from a large telescope in Hawaii called Pan-STARRS (Panoramic Survey Telescope & Rapid Response System), Tingting Liu of the University of Maryland and her colleagues spotted what seem to be periodic variations in the radiation emitted by a quasar — a brilliant beacon of light that outshines the entire galaxy in which it resides — from which light has taken 10.4 billion years to reach Earth. The team reported its findings on 14 April in The Astrophysical Journal Letters.

    Pann-STARSR1 Telescope
    Pann-STARRS2 Interior

    Quasars are thought to be fuelled by supermassive black holes at the centres of galaxies. Liu and her colleagues interpret the apparently periodic fluctuations in the quasar light, along with information gleaned from the spectrum of that light, as a sign that the quasar’s black hole is closely orbiting another supermassive black hole in a neighbouring galaxy. If confirmed, the putative merger would be a prime candidate to examine for signs of emitted gravitational waves, says Liu.

    Signal search

    “This merger would be amazing, if we saw it,” says Miller. But strong evidence for an imminent collision is lacking, he adds. Random, low-frequency fluctuations in the quasar’s light could partially mimic a periodic signal, he notes. And even if fluctuations in the quasar’s light are truly periodic, they could be due to the properties of a single black hole and its disk, rather than to the presence of an orbiting partner, Shapiro says.

    Still, he adds, it would be worth trying to spot gravitational waves from the putative merger. One way to do this would involve pulsars: compact, rapidly spinning stars that beam radio waves across the sky like lighthouse beacons. If a radio receiver on Earth could detect a correlated change to signals from an array of pulsars, that might indicate that the passage of a gravitational wave had disturbed the array. Radio receivers are not currently sensitive enough to detect a signal from Liu’s system, but future improvements could bring a detection within reach, says Shapiro.

    Earlier this year, astronomers reported in Nature that they had found a repeating light signal that is best explained by a pair of supermassive black holes poised to spiral into each other. Sadly, the collision is predicted to occur a million years from now.

    See the full article here.

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  • richardmitnick 1:52 pm on April 7, 2015 Permalink | Reply
    Tags: , Black Holes,   

    From SUNY Buffalo: “Black holes don’t erase information, scientists say” 

    SUNY Buffalo

    SUNY Buffalo

    April 2, 2015
    Charlotte Hsu

    An artist’s impression shows the surroundings of a supermassive black hole at the heart of the active galaxy NGC 3783 in the southern constellation of Centaurus. A new University at Buffalo study finds that information is not lost once it has entered a black hole. Credit: ESO/M. Kornmesser

    The “information loss paradox” in black holes — a problem that has plagued physics for nearly 40 years — may not exist

    Shred a document, and you can piece it back together. Burn a book, and you could theoretically do the same. But send information into a black hole, and it’s lost forever.

    That’s what some physicists have argued for years: That black holes are the ultimate vaults, entities that suck in information and then evaporate without leaving behind any clues as to what they once contained.

    But new research shows that this perspective may not be correct.

    “According to our work, information isn’t lost once it enters a black hole,” says Dejan Stojkovic, PhD, associate professor of physics at the University at Buffalo. “It doesn’t just disappear.”

    Stojkovic’s new study, Radiation from a Collapsing Object is Manifestly Unitary, appeared on March 17 in Physical Review Letters, with UB PhD student Anshul Saini as co-author.

    The paper outlines how interactions between particles emitted by a black hole can reveal information about what lies within, such as characteristics of the object that formed the black hole to begin with, and characteristics of the matter and energy drawn inside.

    This is an important discovery, Stojkovic says, because even physicists who believed information was not lost in black holes have struggled to show, mathematically, how this happens. His new paper presents explicit calculations demonstrating how information is preserved, he says.

    The research marks a significant step toward solving the “information loss paradox,” a problem that has plagued physics for almost 40 years, since Stephen Hawking first proposed that black holes could radiate energy and evaporate over time. This posed a huge problem for the field of physics because it meant that information inside a black hole could be permanently lost when the black hole disappeared — a violation of quantum mechanics, which states that information must be conserved.

    Information hidden in particle interactions

    In the 1970s, Hawking proposed that black holes were capable of radiating particles, and that the energy lost through this process would cause the black holes to shrink and eventually disappear. Hawking further concluded that the particles emitted by a black hole would provide no clues about what lay inside, meaning that any information held within a black hole would be completely lost once the entity evaporated.

    Though Hawking later said he was wrong and that information could escape from black holes, the subject of whether and how it’s possible to recover information from a black hole has remained a topic of debate.

    Stojkovic and Saini’s new paper helps to clarify the story.

    Instead of looking only at the particles a black hole emits, the study also takes into account the subtle interactions between the particles. By doing so, the research finds that it is possible for an observer standing outside of a black hole to recover information about what lies within.

    Interactions between particles can range from gravitational attraction to the exchange of mediators like photons between particles. Such “correlations” have long been known to exist, but many scientists discounted them as unimportant in the past.

    “These correlations were often ignored in related calculations since they were thought to be small and not capable of making a significant difference,” Stojkovic says. “Our explicit calculations show that though the correlations start off very small, they grow in time and become large enough to change the outcome.”

    The study was partially funded by the National Science Foundation.

    See the full article here.

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  • richardmitnick 8:57 am on March 26, 2015 Permalink | Reply
    Tags: , , Black Holes,   

    From Space.com: “The Strangest Black Holes in the Universe” 2013 But Interesting 

    space-dot-com logo


    July 08, 2013
    Charles Q. Choi

    Black holes are gigantic cosmic monsters, exotic objects whose gravity is so strong that not even light can escape their clutches.

    The Biggest Black Holes
    Credit: Pete Marenfeld

    Nearly all galaxies are thought to harbor at their cores supermassive black holes millions to billions of times the mass of our sun. Scientists recently discovered the largest black holes known in two nearby galaxies.

    One of these galaxies, known as NGC 3842 — the brightest galaxy in the Leo cluster nearly 320 million light years away — has a central black hole containing 9.7 billion solar masses. The other, NGC 4889, the brightest galaxy in the Coma cluster more than 335 million light years away, has a black hole of comparable or larger mass.

    NGC 4889
    Credit: Sloan Digital Sky Survey, Spitzer Space Telescope
    Sloan Digital Sky Survey Telescope
    SDSS telescope

    NASA Spitzer Telescope

    The Smallest Black Hole
    Credit: NASA/Goddard Space Flight Center/CI Lab

    The gravitational range, or “event horizon,” of these black holes is about five times the distance from the sun to Pluto. For comparison, these blaVck holes are 2,500 times as massive as the black hole at the center of the Milky Way galaxy, whose event horizon is one-fifth the orbit of Mercury.

    The smallest black hole discovered to date may be less than three times the mass of our sun. This would put this little monster, officially called IGR J17091-3624, near the theoretical minimum limit needed for a black hole to be stable. As tiny as this black hole may be, it looks fierce, capable of 20 million mph winds (32 million kph) — the fastest yet observed from a stellar-mass black hole by nearly 10 times.

    Cannibalistic Black Holes
    Credit: X-ray: NASA/CXC/SAO/G.Fabbiano et al; Optical: NASA/STScI

    NASA Chandra schematic

    NASA Hubble Telescope
    NASA/ESA Hubble [not in notes but in credit]

    Black holes devour anything unlucky enough to drift too close, including other black holes. Scientists recently detected the monstrous black hole at the heart of one galaxy getting consumed by a still larger black hole in another.

    The discovery is the first of its kind. Astronomers had witnessed the final stages of the merging of galaxies of equal mass — so-called major mergers — but minor mergers between galaxies and smaller companions had long eluded researchers.

    Using NASA’s Chandra X-ray Observatory, investigators detected two black holes at the center of a galaxy dubbed NGC3393, with one black hole about 30 million times the mass of the sun and the other at least 1 million times the mass of the sun, separated from each other by only about 490 light-years.

    Bullet-shooting Black Hole
    Credit: Greg Sivakoff/University of Alberta

    Black holes are known for sucking in matter, but researchers find they can shoot it out as well. Observations of a black hole called H1743-322, which harbors five to 10 times the mass of the sun and is located about 28,000 light-years from Earth, revealed it apparently pulled matter off a companion star, then spat some of it back out as gigantic “bullets” of gas moving at nearly a quarter the speed of light.

    The Oldest Known Black Hole
    Credit: ESO/M. Kornmesser

    The oldest black hole found yet, officially known as ULAS J1120+0641, was born about 770 million years after the Big Bang that created our universe. (Scientists think the Big Bang occurred about 13.7 billion years ago.)

    The ancient age of this black hole actually poses some problems for astronomers. This brilliant enigma appears to be 2 billion times the mass of the sun. How black holes became so massive so soon after the Big Bang is difficult to explain.

    The Brightest Black Hole
    Credit: HST

    Although the gravitational pulls of black holes are so strong that even light cannot escape, they also make up the heart of quasars, the most luminous, most powerful and most energetic objects in the universe.

    As supermassive black holes at the centers of galaxies suck in surrounding gas and dust, they can spew out huge amounts of energy. The brightest quasar we see in the visible range is 3C 273, which lies about 3 billion light-years away.

    Rogue Black Holes
    Credit: David A. Aguilar (CfA)

    When galaxies collide, black holes can get kicked away from the site of the crash to roam freely through space. The first known such rogue black hole, SDSSJ0927+2943, may be approximately 600 million times the mass of the sun and hurtle through space at a whopping 5.9 million mph (9.5 million kph). Hundreds of rogue black holes might wander the Milky Way.

    Middleweight Black Holes
    Credit: NASA

    Scientists have long thought that black holes come in three sizes — essentially small, medium and large. Relatively small black holes holding the mass of a few suns are common, while supermassive black holes millions to billions of solar masses are thought to lurk at the heart of nearly every galaxy. One more massive than four million suns, for example, is thought to hide in the center of the Milky Way.

    However, middle-weight black holes had eluded astronomers for years. Scientists recently discovered an intermediate-mass black hole, called HLX-1 (Hyper-Luminous X-ray source 1), approximately 290 million light-years from Earth, which appears to be about 20,000 solar masses in size.

    Medium-size black holes are thought to be the building blocks of supermassive black holes, so understanding more about them can shed light on how these monsters and the galaxies that surround them evolved.

    Fastest-spinning Black Hole
    Credit: NASA / NASA / CXC / M.Weiss

    Black holes can whirl the fabric of space around themselves at extraordinary speeds. One black hole called GRS 1915+105, in the constellation Aquila (The Eagle) about 35,000 light-years from Earth, is spinning more than 950 times per second.

    An item placed on the edge of the black hole’s event horizon — the edge past which nothing can escape — would spin around it at a speed of more than 333 million mph (536 million kph), or about half the speed of light.

    Tabletop Black Holes
    Credit: Chris Kuklewicz

    Black holes are thankfully quite far away from Earth, but this distance makes it difficult to gather clues that could help solve the many mysteries that surround them. However, researchers are now recreating the enigmatic properties of black holes on tabletops.

    For instance, black holes possess gravitational pulls so powerful that nothing, including light, can escape after falling past a border known as the event horizon. Scientists have created an artificial event horizon in the lab using fiber optics. They have also recreated the so-called Hawking radiation thought to escape from black holes.

    See the full article here.

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  • richardmitnick 6:46 am on March 26, 2015 Permalink | Reply
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    From ESO: “Best View Yet of Dusty Cloud Passing Galactic Centre Black Hole” 

    European Southern Observatory

    26 March 2015
    Andreas Eckart
    University of Cologne
    Cologne, Germany
    Email: eckart@ph1.uni-koeln.de

    Monica Valencia-S.
    University of Cologne
    Cologne, Germany
    Email: mvalencias@ph1.uni-koeln.de

    Richard Hook
    ESO, Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    VLT observations confirm that G2 survived close approach and is a compact object

    Temp 0

    The best observations so far of the dusty gas cloud G2 confirm that it made its closest approach to the supermassive black hole at the centre of the Milky Way in May 2014 and has survived the experience. The new result from ESO’s Very Large Telescope shows that the object appears not to have been significantly stretched and that it is very compact. It is most likely to be a young star with a massive core that is still accreting material. The black hole itself has not yet shown any increase in activity.

    A supermassive black hole with a mass four million times that of the Sun lies at the heart of the Milky Way galaxy. It is orbited by a small group of bright stars and, in addition, an enigmatic dusty cloud, known as G2, has been tracked on its fall towards the black hole over the last few years. Closest approach, known as peribothron, was predicted to be in May 2014.

    The great tidal forces in this region of very strong gravity were expected to tear the cloud apart and disperse it along its orbit. Some of this material would feed the black hole and lead to sudden flaring and other evidence of the monster enjoying a rare meal. To study these unique events, the region at the galactic centre has been very carefully observed over the last few years by many teams using large telescopes around the world.

    A team led by Andreas Eckart (University of Cologne, Germany) has observed the region using ESO’s Very Large Telescope (VLT) [1] over many years, including new observations during the critical period from February to September 2014, just before and after the peribothron event in May 2014. These new observations are consistent with earlier ones made using the Keck Telescope on Hawaii [2].

    Keck Observatory
    Keck Observatory Interior

    The images of infrared light coming from glowing hydrogen show that the cloud was compact both before and after its closest approach, as it swung around the black hole.

    As well as providing very sharp images, the SINFONI instrument on the VLT also splits the light into its component infrared colours and hence allows the velocity of the cloud to be estimated [3].


    Before closest approach, the cloud was found to be travelling away from the Earth at about ten million kilometres/hour and, after swinging around the black hole, it was measured to be approaching the Earth at about twelve million kilometres/hour.

    Florian Peissker, a PhD student at the University of Cologne in Germany, who did much of the observing, says: “Being at the telescope and seeing the data arriving in real time was a fascinating experience,” and Monica Valencia-S., a post-doctoral researcher also at the University of Cologne, who then worked on the challenging data processing adds: “It was amazing to see that the glow from the dusty cloud stayed compact before and after the close approach to the black hole.”

    Although earlier observations had suggested that the G2 object was being stretched, the new observations did not show evidence that the cloud had become significantly smeared out, either by becoming visibly extended, or by showing a larger spread of velocities.

    In addition to the observations with the SINFONI instrument the team has also made a long series of measurements of the polarisation of the light coming from the supermassive black hole region using the NACO instrument on the VLT.


    These, the best such observations so far, reveal that the behaviour of the material being accreted onto the black hole is very stable, and — so far — has not been disrupted by the arrival of material from the G2 cloud.

    The resilience of the dusty cloud to the extreme gravitational tidal effects so close to the black hole strongly suggest that it surrounds a dense object with a massive core, rather than being a free-floating cloud. This is also supported by the lack, so far, of evidence that the central monster is being fed with material, which would lead to flaring and increased activity.

    Andreas Eckart sums up the new results: “We looked at all the recent data and in particular the period in 2014 when the closest approach to the black hole took place. We cannot confirm any significant stretching of the source. It certainly does not behave like a coreless dust cloud. We think it must be a dust-shrouded young star.”


    [1] These are very difficult observations as the region is hidden behind thick dust clouds, requiring observations in infrared light. And, in addition, the events occur very close to the black hole, requiring adaptive optics to get sharp enough images. The team used the SINFONI instrument on ESO’s Very Large Telescope and also monitored the behaviour of the central black hole region in polarised light using the NACO instrument.

    [2] The VLT observations are both sharper (because they are made at shorter wavelengths) and also have additional measurements of velocity from SINFONI and polarisation measurement using the NACO instrument.

    [3] Because the dusty cloud is moving relative to Earth — away from Earth before closest approach to the black hole and towards Earth afterwards — the Doppler shift changes the observed wavelength of light. These changes in wavelength can be measured using a sensitive spectrograph such as the SINFONI instrument on the VLT. It can also be used to measure the spread of velocities of the material, which would be expected if the cloud was extended along its orbit to a significant extent, as had previously been reported.

    More information

    This research was presented in a paper Monitoring the Dusty S-Cluster Object (DSO/G2) on its Orbit towards the Galactic Center Black Hole by M. Valencia-S. et al. in the journal Astrophysical Journal Letters.

    The team is composed of M. Valencia-S. (Physikalisches Institut der Universität zu Köln, Germany), A. Eckart (Universität zu Köln; Max-Planck-Institut für Radioastronomie, Bonn, Germany [MPIfR]), M. Zajacek (Universität zu Köln; MPIfR; Astronomical Institute of the Academy of Sciences Prague, Czech Republic), F. Peissker (Universität zu Köln), M. Parsa (Universität zu Köln), N. Grosso (Observatoire Astronomique de Strasbourg, France), E. Mossoux (Observatoire Astronomique de Strasbourg), D. Porquet (Observatoire Astronomique de Strasbourg), B. Jalali (Universität zu Köln), V. Karas (Astronomical Institute of the Academy of Sciences Prague), S. Yazici (Universität zu Köln), B. Shahzamanian (Universität zu Köln), N. Sabha (Universität zu Köln), R. Saalfeld (Universität zu Köln), S. Smajic (Universität zu Köln), R. Grellmann (Universität zu Köln), L. Moser (Universität zu Köln), M. Horrobin (Universität zu Köln), A. Borkar (Universität zu Köln), M. García-Marín (Universität zu Köln), M. Dovciak (Astronomical Institute of the Academy of Sciences Prague), D. Kunneriath (Astronomical Institute of the Academy of Sciences Prague), G. D. Karssen (Universität zu Köln), M. Bursa (Astronomical Institute of the Academy of Sciences Prague), C. Straubmeier (Universität zu Köln) and H. Bushouse (Space Telescope Science Institute, Baltimore, Maryland, USA).

    See the full article here.

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    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

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  • richardmitnick 5:19 am on February 25, 2015 Permalink | Reply
    Tags: , Black Holes, , Stephen Hawking   

    From NOVA: “Stephen Hawking Serves Up Scrambled Black Holes” 



    04 Feb 2014
    Greg Kestin

    Out of the firewall and into the frying pan? Credit: Flickr/Pheexies, under a Creative Commons license.

    Toast or spaghetti?

    That’s the question that physicists have been trying to answer for the last year and a half. After agreeing for decades that anything—or anyone—unlucky enough to fall into a black hole would be ripped and stretched into spaghetti-like strands by the overwhelming gravity, theorists are now contending with the possibility that infalling matter is instead incinerated by a “toasty” wall of fire at the black hole’s horizon. Now, Stephen Hawking has proposed a radical solution: nixing one of the most infamous characteristics of a black hole, its event horizon, or point of no return.

    Stephen Hawking

    The original “spaghetti” scenario follows directly from [Albert] Einstein’s theory of general relativity, which describes how gravity stretches the fabric of space and time. A black hole warps that fabric into a bottomless pit; if you get too close, you reach a point of no return called the horizon, where the slope becomes so steep that you can never climb back out. Inside, the gravity gets stronger and stronger until it tears you limb from limb.

    The first hint that there was a flaw in this picture of a black hole came in 1975, when Stephen Hawking came upon a paradox. He realized that, over a very long time, a black hole will “evaporate”—that is, its mass and energy will gradually leak out as radiation, revealing nothing of what the black hole once contained. This was a shocking conclusion because it suggested that black holes destroy information, a fundamental violation of quantum mechanics, which insists that information be conserved.

    How exactly does black hole evaporation imply that information is destroyed? Let’s say you are reading the last copy of “Romeo and Juliet,” and when you get to the end, grief overcomes you (sorry for the spoiler) and you throw the book into a black hole. After the book falls past the horizon, gravity shreds its pages, and finally it is violently compressed into the central point of the black hole. Then you wait as the black hole slowly evaporates by randomly shooting off particles from its glowing edges without any concern for Romeo or Juliet. As the black hole winks out of existence, only these random subatomic particles remain, floating in space. Where did the Montagues and Capulets go? They are lost forever. You could have thrown in “The Cat in The Hat” and the particles left after evaporation would be indistinguishable from the Shakespearian remnants.

    Hawking realized that something had to give. Either quantum mechanics had to change to accommodate information loss, or Einstein’s theory of gravity was flawed.

    Over the past 40 years theorists have battled in the “black hole wars,” trying to resolve this paradox. Two decades ago, most physicists declared a truce, agreeing to consider the inside and the outside of the black hole as separate spaces. If something falls into the black hole, it has gone to another realm, so just stop thinking about it and its fate, they counseled. This argument was largely accepted until July 2012, when UC Santa Barbara physicist Joseph Polchinski and his colleagues realized the paradox was even more puzzling.

    Polchinski began with a similar thought experiment, but instead of Shakespeare, he imagined tossing entangled particles (particles that are quantum mechanically linked) toward a black hole. What happens, he asked, if one particle falls in the black hole and the other flies out into space? This creates a big problem: We can’t think of the two realms (inside and outside of the black hole) separately because they are tied together by the entangled particles.

    Polchinski proposed a new solution that ripped apart Einstein’s idea of a black hole—literally. If there were something to prevent entanglement across the horizon, he thought, then there would be no problem. So he came up with something called a firewall: a wall of radiation at the black hole’s horizon that burns up anything that hits it. This wall is a tear in space-time that nothing can go through.

    Is incineration finally the solution to the black hole information paradox? The father of the paradox, Stephen Hawking, recently put in his two cents (two pages, actually) in a very brief paper in which he argues against not just firewalls, but also event horizons as an ultimate point-of-no-return. This argument relies on quantum fluctuations in space-time that prevent a horizon from existing at a sharp boundary. He instead proposes a temporary “apparent horizon” that stores matter/energy (and information), chaotically scrambles it, and radiates it back out. This means that, as far as quantum mechanics is concerned, information is not lost; it is just extremely garbled. As Polchinski describes it, “It almost sounds like he is replacing the firewall with a chaos-wall!”

    Are you skeptical? If so, you are in good company. Polchinski, for one, is hesitant, saying “It is not clear what [Hawking’s] picture is. There are no calculations.”

    Steve Giddings, a theoretical physicist at the University of California, Santa Barbara, shares in this reluctance:

    “The big question has been how information escapes a black hole, and what that tells us about faster-than-light signaling or a more serious breakdown of spacetime; the effects Hawking describes don’t appear sufficient to address this.”

    Hawking’s new idea will need some flesh on its bones before we can truly embrace it, but if you don’t like spaghetti or toast, at least you have a third option now: scrambled black holes.

    See the full article here.

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    NOVA is the highest rated science series on television and the most watched documentary series on public television. It is also one of television’s most acclaimed series, having won every major television award, most of them many times over.

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