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  • richardmitnick 10:24 am on November 27, 2015 Permalink | Reply
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    From Chandra: All About Black Holes 

    NASA Chandra

    A black hole is a dense, compact object whose gravitational pull is so strong that—within a certain distance of it—nothing can escape, not even light. Black holes range in size from a few times the mass of the Sun to millions or even billions of times the Sun’s mass. Using Chandra, astronomers have learned a great deal about black holes and how they influence their environments. [Here is a primer from NASA/Chandra.]

    Temp 1
    One of the most important black holes to study is the one found at the center of our Milky Way galaxy. Known as Sagittarius A*, this black hole is about 4 million times the mass of the Sun and Chandra has revealed much about its behavior and history. NASA/CXC/Univ. of Wisconsin/Y.Bai. et al.

    [Another view, also from Chandra]


    Temp 2
    Galaxies can merge and when they do, the supermassive black holes at their centers may also collide. This is the case of NGC 6240 where Chandra finds two giant black holes—the bright point-like sources in this middle of the image—are only 3,000 light years apart.X-ray: NASA/CXC/MIT/C.Canizares, M.Nowak; Optical: NASA/STScI

    NASA Hubble Telescope
    NASA/ESA Hubble

    Temp 3
    The galaxy Centaurus A is well known for a spectacular jet of outflowing material—seen pointing from the middle to the upper left in this Chandra image—that is generated by a giant black hole at the galaxy’s center. Chandra has also revealed information about smaller black holes throughout Centaurus A.X-ray: NASA/CXC/U.Birmingham/M.Burke et al.

    See the full article here . I have modified the original article for this post. You are free to visit the full article to download to use as wallpaper.

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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 12:42 pm on November 20, 2015 Permalink | Reply
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    From AAS NOVA: ” Grumblings from an Awakening Black Hole” 


    American Astronomical Society

    20 November 2015
    Susanna Kohler

    Artist’s illustration of a binary black hole system. As the star and the black hole orbit each other, the black hole accretes matter that flows from the star. The black hole V404 Cygni, which is in a binary system with a low-mass star, recently awoke after decades of sleep. [ESO/L. Calçada]

    In June of this year, after nearly three decades of sleep, the black hole V404 Cygni woke up and began grumbling. Scientists across the globe scrambled to observe the sudden flaring activity coming from this previously peaceful black hole. And now we’re getting the first descriptions of what we’ve learned from V404 Cyg’s awakening!

    Sudden Outburst

    V404 Cyg is a black hole of roughly nine solar masses, and it’s in a binary system with a low-mass star. The black hole pulls a stream of gas from the star, which then spirals in around the black hole, forming an accretion disk. Sometimes the material simply accumulates in the disk — but every two or three decades, the build-up of gas suddenly rushes toward the black hole as if a dam were bursting.

    The sudden accretion in these events causes outbursts of activity from the black hole, its flaring easily visible to us. The last time V404 Cyg exhibited such activity was in 1989, and it’s been rather quiet since then. Our telescopes are of course much more powerful and sensitive now, nearly three decades later — so when the black hole woke up and began flaring in June, scientists were delighted at the chance to observe it.

    The high variability of V404 Cyg is evident in this example set of spectra, where time increases from the bottom panel to the top. [King et al. 2015]

    Led by Ashley King (Einstein Fellow at Stanford University), a team of scientists observed V404 Cyg with the Chandra X-ray Observatory, obtaining spectra of the black hole during its outbursts.

    NASA Chandra Telescope

    The black hole flared so brightly during its activity that the team had to take precautions to protect the CCDs in their detector from radiation damage! Now the group has released the first results from their analysis.

    Windy Disk

    The primary surprise from V404 Cyg is its winds. Many stellar-mass black holes have outflows of mass, either in the form of directed jets emitted from their centers, or in the form of high-energy winds isotropically emitted from their accretion disks. But V404 Cyg’s winds — which the authors measure to be moving at a whopping ~4,000 km/s — appear to originate from much further out in the disk than what’s typical. Furthermore, the presence of disk winds and jets is normally anti-correlated, yet in V404 Cyg, both are active at the same time.

    King and collaborators believe that the winds are likely associated with the disruption of the outer accretion disk due to pressure from the radiation in the central region as it becomes very luminous. V404 Cyg’s behavior is actually more similar to that of some supermassive black holes than to most stellar-mass black holes, which is extremely intriguing.

    The authors are currently working to complete a more detailed analysis of the spectra and build a model of the processes occurring in this awakening black hole, but these initial results demonstrate that V404 Cyg has some interesting things to teach us.

    Ashley L. King et al 2015 ApJ 813 L37. doi:10.1088/2041-8205/813/2/L37

    See the full article here .

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  • richardmitnick 11:51 am on October 28, 2015 Permalink | Reply
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    From AAS NOVA: “What Do You Get When Two Neutron Stars Merge?” 


    Amercan Astronomical Society

    28 October 2015
    Susanna Kohler

    Illustration of a binary neutron star system in the process of merging. The remnant formed by this merger could be either a neutron star or a black hole, determining whether it launches a gamma-ray burst. [NASA]

    The merger of two neutron stars (a NS–NS merger) is suspected to be the most likely source of short-duration gamma-ray bursts (GRBs) — powerful explosions that can be seen from billions of light-years away. But whether a GRB is launched is dependent on what remnant is created by the merging NSs. Do they form another NS? Or a black hole (BH)?

    Uncertain Remnant

    If the NS–NS merger forms a BH remnant, a GRB can be launched during the ensuing accretion. But if it instead forms a NS, a GRB may only be launched if the remnant collapses to a BH within 100 milliseconds; any longer, and theory says that the GRB jet will become loaded with baryons and choke.

    Unfortunately, determining whether the merger will produce a NS or a BH is difficult. A major limitation is that we don’t know what equation of state describes the interior of a NS — which means we also don’t know what maximum mass a NS can have before it collapses into a BH.

    Led by Chris Fryer of the University of Arizona and the Los Alamos National Laboratory, a group of researchers undertook a highly collaborative study to better understand the fates of NS–NS mergers.

    The fraction of mergers that produce BHs (and, consequently, GRBs) and NSs, as a function of the maximum NS mass allowed by the equation of state. Lines labeled BHAD are mergers that produce BHs (under two different initial conditions); lines labeled NS are those that produce NSs. [Fryer et al. 2015]

    Maximum Mass

    The authors used a combination of merger calculations, neutron star equation of state studies, and population synthesis simulations to model the outcome of the merger of two NSs. With this information, they determined the statistical likelihood that the remnant that forms in the merger collapses directly to a BH, collapses to a BH after a delay, or remains a NS.

    Fryer and collaborators find that the outcome is highly dependent upon the maximum mass allowed by the uncertain NS equation of state. If this maximum NS mass is below 2.3–2.4 solar masses, most NS mergers will result in a BH within 100 milliseconds of the merger. In this case, most mergers would be capable of producing GRBs. If, on the other hand, the maximum NS mass is above this cutoff, then the majority of NS mergers will form a NS remnant — only rarely launching a GRB.

    Since, to match observed GRB rates, the second scenario requires a rate of mergers significantly higher than what theory predicts, it seems more likely that NS masses are limited to 2.3–2.4 solar masses. Upcoming observational projects like advanced LIGO will help to test this theory and place further constraints on our models of NSs.

    Chris L. Fryer et al 2015 ApJ 812 24. doi:10.1088/0004-637X/812/1/24

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  • richardmitnick 4:09 pm on September 24, 2015 Permalink | Reply
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    From CSIRO: “Eleven year cosmic search leads to black hole rethink” 

    CSIRO bloc

    Commonwealth Scientific and Industrial Research Organisation

    One hundred years since [Albert] Einstein proposed gravitational waves as part of his general theory of relativity, an 11-year search performed with CSIRO’s Parkes telescope has shown that an expected background of waves is missing, casting doubt on our understanding of galaxies and black holes.

    For scientists gravitational waves exert a powerful appeal, as it is believed they carry information allowing us to look back into the very beginnings of the Universe. Although there is strong circumstantial evidence for their existence, they have not yet been directly detected.

    The work, led by Dr Ryan Shannon (of CSIRO and the International Centre for Radio Astronomy Research), is published today in the journal Science.

    Using Parkes, the scientists expected to detect a background ‘rumble’ of the waves, coming from the merging galaxies throughout the Universe, but they weren’t there.

    CSIRO Parkes Observatory
    Parkes Observatory radio telescope

    The world-first research has caused scientists to think about the Universe in a different way.

    “This is probably the most comprehensive, high precision science that’s ever been undertaken in this field of astronomy,” Dr Shannon said.

    “By pushing ourselves to the limits required for this sort of cosmic search we’re moving into new frontiers in all areas of physics, forcing ourselves to understand how galaxies and black holes work.”

    The fact that gravitational waves weren’t detected goes against all theoretical calculations and throws our current understanding of black holes into question.

    Galaxies grow by merging and every large one is thought to have a supermassive black hole at its heart. When two galaxies unite, the black holes are drawn together and form an orbiting pair. At this point, Einstein’s theory is expected to take hold, with the pair predicted to succumb to a death spiral, sending ripples known as gravitational waves through space-time, the very fabric of the Universe.

    Although Einstein’s general theory of relativity has withstood every test thrown at it by scientists, directly detecting gravitational waves remain the one missing piece of the puzzle.

    To look for the waves, Dr Shannon’s team used the Parkes telescope to monitor a set of ‘millisecond pulsars’. These small stars produce highly regular trains of radio pulses and act like clocks in space. The scientists recorded the arrival times of the pulsar signals to an accuracy of ten billionths of a second.

    A gravitational wave passing between Earth and a millisecond pulsar squeezes and stretches space, changing the distance between them by about 10 metres — a tiny fraction of the pulsar’s distance from Earth. This changes, very slightly, the time that the pulsar’s signals arrive on Earth.

    The scientists studied their pulsars for 11 years, which should have been long enough to reveal gravitational waves.

    So why haven’t they been found? There could be a few reasons, but the scientists suspect it’s because black holes merge very fast, spending little time spiralling together and generating gravitational waves.

    “There could be gas surrounding the black holes that creates friction and carries away their energy, letting them come to the clinch quite quickly,” said team member Dr Paul Lasky, a postdoctoral research fellow at Monash University.

    Whatever the explanation, it means that if astronomers want to detect gravitational waves by timing pulsars they’ll have to record them for many more years.

    “There might also be an advantage in going to a higher frequency,” said Dr Lindley Lentati of the University of Cambridge, UK, a member of the research team who specialises in pulsar-timing techniques. Astronomers will also gain an advantage with the highly sensitive Square Kilometre Array telescope, set to start construction in 2018.

    SKA Square Kilometer Array

    Not finding gravitational waves through pulsar timing has no implications for ground-based gravitational wave detectors such as Advanced LIGO (the Laser Interferometer Gravitational-Wave Observatory), which began its own observations of the Universe last week.

    Advanced Ligo
    Advanced LIGO

    “Ground-based detectors are looking for higher-frequency gravitational waves generated by other sources, such as coalescing neutron stars,” said Dr Vikram Ravi, a member of the research team from Swinburne University (now at Caltech, in Pasadena, California).

    See the full article here .

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    CSIRO campus

    CSIRO, the Commonwealth Scientific and Industrial Research Organisation, is Australia’s national science agency and one of the largest and most diverse research agencies in the world.

  • richardmitnick 4:14 pm on September 16, 2015 Permalink | Reply
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    From JPL: “Funky Light Signal From Colliding Black Holes Explained” 


    September 16, 2015
    Whitney Clavin
    Jet Propulsion Laboratory, Pasadena, California

    This simulation helps explain an odd light signal thought to be coming from a close-knit pair of merging black holes, PG 1302-102, located 3.5 billion light-years away. Image credit: Columbia University

    Entangled by gravity and destined to merge, two candidate black holes in a distant galaxy appear to be locked in an intricate dance. Researchers using data from NASA’s Galaxy Evolution Explorer (GALEX) and NASA’s Hubble Space Telescope have come up with the most compelling confirmation yet for the existence of these merging black holes and have found new details about their odd, cyclical light signal.

    NASA Galex telescope

    NASA Hubble Telescope
    NASA/ESA Hubble

    The candidate black hole duo, called PG 1302-102, was first identified earlier this year using ground-based telescopes.

    Mt Lemon 24 inch telescope
    Mt Lemon telescope

    Caltech Catalina Real Time Survey Telescope
    Caltech Catalina Real Time Survey Telescope

    The black holes are the tightest orbiting pair detected so far, with a separation not much bigger than the diameter of our solar system. They are expected to collide and merge in less than a million years, triggering a titanic blast with the power of 100 million supernovae.

    Researchers are studying this pair to better understand how galaxies and the monstrous black holes at their cores merge — a common occurrence in the early universe. But as common as these events were, they are hard to spot and confirm.

    PG 1302-102 is one of only a handful of good binary black hole candidates. It was discovered and reported earlier this year by researchers at the California Institute of Technology3 in Pasadena, after they scrutinized an unusual light signal coming from the center of a galaxy. The researchers, who used telescopes in the Catalina Real-Time Transient Survey, demonstrated that the varying signal is likely generated by the motion of two black holes, which swing around each other every five years. While the black holes themselves don’t give off light, the material surrounding them does.

    In the new study, published in the Sept. 17 issue of Nature, researchers found more evidence to support and confirm the close-knit dance of these black holes. Using ultraviolet data from GALEX and Hubble, they were able to track the system’s changing light patterns over the past 20 years.

    “We were lucky to have GALEX data to look through,” said co-author David Schiminovich of Columbia University in New York. “We went back into the GALEX archives and found that the object just happened to have been observed six times.”

    Hubble, which sees ultraviolet light in addition to visible and other wavelengths of light, had likewise observed the object in the past.

    The ultraviolet light was important to test a prediction of how the black holes generate a cyclical light pattern. The idea is that one of the black holes in the pair is giving off more light — it is gobbling up more matter than the other one, and this process heats up matter that emits energetic light. As this black hole orbits around its partner every five years, its light changes and appears to brighten as it heads toward us.

    “It’s as if a 60-Watt light bulb suddenly appears to be 100 Watts,” explained Daniel D’Orazio, lead author of the study from Columbia University. “As the black hole light speeds away from us, it appears as a dimmer 20-Watt bulb.”

    What’s causing the changes in light? One set of changes has to do with the “blue shifting” effect, in which light is squeezed to shorter wavelengths as it travels toward us in the same way that a police car’s siren squeals at higher frequencies as it heads toward you. Another reason has to do with the enormous speed of the black hole.

    The brighter black hole is, in fact, traveling at nearly seven percent the speed of light — in other words, really fast. Though it takes the black hole five years to orbit its companion, it is traveling vast distances. It would be as if a black hole lapped our entire solar system from the outer fringes, where the Oort cloud of comets lies, in just five years. At speeds as high as this, which are known as relativistic, the light becomes boosted and brighter.

    D’Orazio and colleagues modeled this effect based on a previous Caltech paper and predicted how it should look in ultraviolet light. They determined that, if the periodic brightening and dimming previously seen in the visible light is indeed due to the relativistic boosting effect, then the same periodic behavior should be present in ultraviolet wavelengths, but amplified 2.5 times. Sure enough, the ultraviolet light from GALEX and Hubble matched their predictions.

    “We are strengthening our ideas of what’s going on in this system and starting to understand it better,” said Zoltan Haiman, a co-author from Columbia University who conceived the project.

    The results will also help researchers understand how to find even closer-knit merging black holes in the future, what some consider the holy grail of physics and the search for gravitational waves. In the final moments before the ultimate union of two black holes, when they are tightly spinning around each other like ice skaters in a “death spiral,” they are predicted to send out ripples in space and time. These so-called gravitational waves, whose existence follows from Albert Einstein’s gravity theory published 100 years ago, hold clues about the fabric of our universe.

    The findings are also a doorway to understanding other merging black holes across the universe, a widespread population that is only now beginning to yield its secrets.

    The California Institute of Technology in Pasadena led the Galaxy Evolution Explorer mission, which ended in 2013 after more than a decade of scanning the skies in ultraviolet light. NASA’s Jet Propulsion Laboratory, also in Pasadena, managed the mission and built the science instrument. JPL is managed by Caltech for NASA.

    The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington.

    For more information about GALEX, visit:



    For more information on the Hubble Space Telescope, visit:


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    NASA JPL Campus

    Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. Although the facility has a Pasadena postal address, it is actually headquartered in the city of La Cañada Flintridge [1], on the northwest border of Pasadena. JPL is managed by the nearby California Institute of Technology (Caltech) for the National Aeronautics and Space Administration. The Laboratory’s primary function is the construction and operation of robotic planetary spacecraft, though it also conducts Earth-orbit and astronomy missions. It is also responsible for operating NASA’s Deep Space Network.

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  • richardmitnick 8:41 pm on September 11, 2015 Permalink | Reply
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    From UCSC: “Study finds different ways for a black hole to swallow a star” 

    UC Santa Cruz

    UC Santa Cruz

    September 10, 2015
    Susanna Kohler (AAS) and Tim Stephens (UCSC)

    In this simulated tidal disruption event, a star is pulled apart by the tidal forces of a black hole. (Image credit: NASA/S. Gezari, JHU/J. Guillochon, UCSC)

    In a tidal disruption event, an unfortunate star passes too close to a dormant supermassive black hole and gets torn apart by tidal forces, feeding the black hole for a short time. Astronomers use distinctive observational signatures to detect these events, but they are not seeing nearly as many tidal disruption events as theory says they should.

    A recent study by UC Santa Cruz researchers suggests that astronomers might be missing many of these events because of how the streams of shredded stars fall onto the black hole. James Guillochon, who earned his Ph.D. at UC Santa Cruz and is now at the Harvard-Smithsonian Center for Astrophysics, and Enrico Ramirez-Ruiz, professor and chair of astronomy and astrophysics, based their analysis on a series of computer simulations of tidal disruption events. They reported their findings in a paper published August 20 in the Astrophysical Journal.

    When a black hole tears a star apart, the star’s material is stretched out into what’s known as a tidal stream. That stream continues on a trajectory around the black hole, with roughly half the material eventually falling back on the black hole, whipping around it in a series of orbits. Where those orbits intersect each other, the material smashes together and circularizes, forming a disk that then accretes onto the black hole.

    Astronomers don’t observe anything until after the tidal streams collide and the material begins to accrete onto the black hole. At that point, they observe a sudden peak in luminosity, which then gradually decreases as the tail end of what’s left of the star accretes and the black hole’s food source eventually runs out.

    General relativity

    So why have astronomers only been observing about a tenth as many tidal disruption events (TDEs) as theory predicts they should see? By studying the structure of tidal streams in TDEs, Guillochon and Ramirez-Ruiz have found a potential reason, and the culprit is general relativity.

    “It is an effect of general relativity that is modulating the digestion process of the black hole, so the digestion rate depends strongly on the mass of the black hole,” Ramirez-Ruiz said.

    The researchers ran a series of simulations of tidal disruption events around black holes of varying masses and spins to see what form the resulting tidal streams take over time. They found that precession of the tidal stream due to the black hole’s gravitational effects changes how the stream interacts with itself, and therefore what astronomers observe. Some cases behave as expected for what’s currently considered a “typical” event, but some do not.

    For cases where the relativistic effects are small (such as black holes with masses less than a few million solar masses), the tidal stream collides with itself after only a few windings around the black hole, quickly forming a disk — but the disk forms far from the black hole, so it takes a long time to accrete. As a result, the observed flare can take 100 times longer to peak than typically expected, so these sources may not be identified as tidal disruption events.

    Furthermore, for cases where the black hole is both massive and has a spin greater than a certain value (about 20 percent of its maximum allowed spin), the tidal stream doesn’t collide with itself right away. Instead, it can take many windings around the black hole before the first intersection. In these cases, it may potentially be years after a star gets ripped apart before the material accretes and astronomers are able to observe the event.

    See the full article here .

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    The University of California, Santa Cruz, opened in 1965 and grew, one college at a time, to its current (2008-09) enrollment of more than 16,000 students. Undergraduates pursue more than 60 majors supervised by divisional deans of humanities, physical & biological sciences, social sciences, and arts. Graduate students work toward graduate certificates, master’s degrees, or doctoral degrees in more than 30 academic fields under the supervision of the divisional and graduate deans. The dean of the Jack Baskin School of Engineering oversees the campus’s undergraduate and graduate engineering programs.

  • richardmitnick 2:22 pm on September 9, 2015 Permalink | Reply
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    From Symmetry: “The birth of a black hole, live” 


    September 09, 2015
    Lauren Biron

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

    Black holes fascinate us. We easily conjure up images of them swallowing spaceships, but we know very little about these strange objects. In fact, we’ve never even seen a black hole form. Scientists on neutrino experiments such as the upcoming Deep Underground Neutrino Experiment hope to change that.

    FNAL Dune & LBNF

    “You’ve got to be a bit lucky,” says Mark Thomson, DUNE co-spokesperson. “But it would be one of the major discoveries in science. It would be absolutely incredible.”

    Black holes are sometimes born when a massive star, typically more than eight times the mass of our own sun, collapses. But there are a lot of questions about what exactly happens during the process: How often do these collapsing stars give rise to black holes? When in the collapse does the black hole actually develop?

    What scientists do know is that deep in the dense core of the star, protons and electrons are squeezed together to form neutrons, sending ghostly particles called neutrinos streaming out. Matter falls inward. In the textbook case, matter rebounds and erupts, leaving a neutron star. But sometimes, the supernova fails, and there’s no explosion; instead, a black hole is born.

    DUNE’s gigantic detectors, filled with liquid argon, will sit a mile below the surface in a repurposed goldmine. While much of their time will be spent looking for neutrinos sent from Fermi National Accelerator Laboratory 800 miles away, the detectors will also have the rare ability to pick up a core collapse in our Milky Way galaxy – whether or not that leads to a new black hole.

    The only supernova ever recorded by neutrino detectors occurred in in 1987, when scientists saw a total of 19 neutrinos.

    Remnant of SN 1987A seen in light overlays of different spectra. ALMA data (radio, in red) shows newly formed dust in the center of the remnant. Hubble (visible, in green) and Chandra (X-ray, in blue) data show the expanding shock wave.

    ALMA Array

    NASA Hubble Telescope
    NASA/ESA Hubble

    NASA Chandra Telescope

    Scientists still don’t know if that supernova formed a black hole or a neutron star—there simply wasn’t enough data. Thomson says that if a supernova goes off nearby, DUNE could see up to 10,000 neutrinos.

    DUNE will look for a particular signature in the neutrinos picked up by the detector. It’s predicted that a black hole will form relatively early in a supernova. Neutrinos will be able to leave the collapse in great numbers until the black hole emerges, trapping everything—including light and neutrinos—in its grasp. In data terms, that means you’d get a big burst of neutrinos with a sudden cutoff.

    Neutrinos come in three types, called flavors: electron, muon and tau. When a star explodes, it emits all the various types of neutrinos, as well as their antiparticles.

    They’re hard to catch. These neutrinos arrive with 100 times less energy than those arriving from an accelerator for experiments, which makes them less likely to interact in a detector.

    Most of the currently running, large particle detectors capable of seeing supernova neutrinos are best at detecting electron antineutrinos—and not great at detecting their matter equivalents, electron neutrinos.

    “It would be a tragedy to not be ready to detect the neutrinos in full enough detail to answer key questions,” says John Beacom, director of the Center for Cosmology and Astroparticle Physics at The Ohio State University.

    Luckily, DUNE is unique. “The only one that is sensitive to a huge slug of electron neutrinos is DUNE, and that’s a function of using argon [as the detector fluid],” says Kate Scholberg, professor of physics at Duke University.

    It will take more than just DUNE to get the whole picture, though. Getting an entire suite of large, powerful detectors of different types up and running is the best way to figure out the lives of black holes, Beacom says.

    There is a big scintillator detector, JUNO, in the works in China, and plans for a huge water-based detector, Hyper-K, in Japan. Gravitational wave detectors such as LIGO could pick up additional information about the density of matter and what’s happening in the collapse.

    JUNO Chinese Neutrino Experiment
    JUNO Neutrino detector China


    Caltech LIGO
    Caltech LIGO

    “My dream is to have a supernova with JUNO, Hyper-K and DUNE all online,” Scholberg says. “It would certainly make my decade.”

    The rate at which neutrinos arrive after a supernova will tell scientists about what’s happening at the center of a core collapse—but it will also provide information about the mysterious neutrino, including how they interact with each other and potential insights as to how much the tiny particles actually weigh.

    Within the next three years, the rapidly growing DUNE collaboration will build and begin testing a prototype of the 40,000-ton liquid argon detector. This 400-ton version will be the second-largest liquid-argon experiment ever built to date. It is scheduled for testing at CERN starting in 2018.

    DUNE is scheduled to start installing the first of its four detectors in the Sanford Underground Research Facility in 2021.

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.

  • richardmitnick 12:05 pm on September 6, 2015 Permalink | Reply
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    From CNN: “Has Stephen Hawking solved the mystery of black holes?” 


    September 4, 2015
    FNAL Don Lincoln
    Don Lincoln, FNAL

    Black holes have a way of capturing our imagination. That’s why when Stephen Hawking recently talked about them the media went wild.

    Stephen Hawking
    Stephen Hawking

    But what was he really saying? Was it a breakthrough moment?

    At the Hawking Radiation Conference organized by Laura Mersini-Houghton, a professor of physics at the University of North Carolina, 32 eminent physicists gathered to discuss outstanding issues involved with apparent contradictions in our current understanding of the theories of [General] relativity and quantum mechanics. The convergence of the two take us to the inner workings of black holes.

    Black holes are ravenous monsters of the cosmos, constantly reaching out and gobbling nearby mass as they grow larger and larger. The poster child of [Albert] Einstein’s theory of relativity, black holes exert such a strong gravitational force that not even light can escape, and they are able to distort the very fabric of space and slow the passage of time. These are very real objects.

    And yet they embody a very significant mystery. Black holes are said to absorb matter and never let it go. The matter simply disappears inside the black hole. But matter is more than, well, matter. It is information. For instance, if I have a single atom of hydrogen, I have a proton and electron. That’s matter. But there is also information in how they are connected. Are they near one another, or far apart?

    The information component is even more important in, say, a piece of fruit. While I might tell you just how many protons, neutrons and electrons exist in an apple, without the information that tells you how they arranged, it wouldn’t have the apple’s tart taste. In fact, it wouldn’t be an apple at all. Ultimately, it is information that is at the heart of the mystery.

    According to the rules of quantum mechanics, information should never be lost, not even if it gets sucked inside the black hole. This is because of two premises: causality and reversibility. Taken together, it means that effects have causes, and those causes can be undone.

    For example, you can break a glass and then find all the pieces and glue it back together. Yet, these two premises don’t hold for a classical black hole, in which the information is permanently and irreversibly lost as it enters the black hole.

    Note that information being lost isn’t the same as matter being lost. In the 1970s, Hawking postulated what is now called Hawking radiation, which in principle, cause black holes eventually to evaporate as the radiation carries away energy. However, Hawking radiation should be completely independent of the matter absorbed by a black hole. So, information really does appear to be lost, in complete contradiction of quantum theory.

    This is where Hawking’s announcement comes in. He is saying that he can solve the conundrum.

    He is countering the claim that the black hole gobbles and destroys the information by positing that the information never actually falls into the black hole. Instead, the information is held on the black hole’s surface — the event horizon.

    This is an intriguing thought and is analogous to how holograms are made. Holograms are two-dimensional sheets of, for example, plastic that can make three-dimensional images. All of the information of three dimensions is encoded in the two dimensional plastic. (By the way, there are some who hypothesize that our entire universe is a hologram!)

    It is difficult to properly evaluate Hawking’s announcement. The claim as it has been described is not very precise. There is no paper published on the idea, nor has the idea passed peer review. In fact, scientists who attended the conference are still trying to absorb the idea and to cast it in a mathematical language so that the implication can be assessed.

    Hawking developed this concept in collaboration with Malcolm Perry of Cambridge University and Andrew Strominger of Harvard University. They plan to submit a paper in a month or so. That’s when the real evaluation of the proposal can begin.

    While everyone would much prefer to hear about a definitive advancement in science, the actual process of developing scientific ideas can be both intellectually stimulating and thoroughly messy.

    Stephen Hawking’s new ideas are certainly interesting and may point us in the right direction. But we will have to wait a bit longer to solve the enigma of what happens when information confronts a black hole. Sit tight, we’re on a very long journey.

    See the full article here.

    Please help promote STEM in your local schools.

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  • richardmitnick 9:37 am on September 3, 2015 Permalink | Reply
    Tags: , , Black Holes,   

    From NOVA: “How big a deal was Stephen Hawking’s big black hole announcement?” 



    02 Sep 2015
    Sarah Scoles

    “Can you hear me?” Stephen Hawking asked as he was about to begin his August 25 talk at the Royal Institute of Technology’s “Hawking Radiation” conference in Stockholm.

    Stephen Hawking

    The 29-person audience, all VIP physicists, was eager to hear his big announcement and could hear him just fine. They knew, from a pre-announcement announcement the previous night, that Hawking was about to explain his solution to a 40-year-old mystery in physics: how information escapes from black holes.

    But while his idea made big headlines, the mere nine minutes of explanation felt vague and confusing to other physicists.

    The iconic image of a black hole. But, of course, we have never really seen a black hole, not even a supermassive black hole. Artist’s concept illustrates a supermassive black hole with millions to billions times the mass of our sun. Credit: NASA/JPL-Caltech

    What is Hawking’s problem?

    Hawking set out to resolve a problem called the “information paradox.” Understanding this snag requires a brush-up on black holes. If light or matter venture past a boundary around the black hole called the “event horizon,” they are done for: The speed required to overcome the black hole’s gravity and escape is greater than the speed of light [c]. So anything that crosses the event horizon—and any information about what it was in its previous life—stays inside the black hole. Whether you, a Snickers bar, or a whole planet fall in, they all end up the same: as anonymous extra mass piled onto the black hole itself.

    Or at least that used to be the idea. Then, in 1974, Stephen Hawking showed that black holes slowly evaporate. They continuously leak radiation (later named “Hawking radiation”), dwindling away until there’s nothing left, on timescales ranging form a few billion years to much longer than the current age of the universe. But, as theoretical physicist Carlo Rovelli of Aix-Marseille University, who attended the talk, explains, “This creates a problem: Where has all the stuff gone that fell inside? Where is the information about what fell in? It cannot be anymore ‘just inside,’ because the black hole has disappeared. So, where is it? Is it really lost?”

    Quantum mechanics says that information about the stuff can’t be lost. Information can neither be created nor destroyed. But black holes seem to destroy it. But they can’t. But they seem to. That’s the “paradox” part of the information paradox.

    Some scientists think the escaping Hawking radiation carries the information out with it, like a set-free hostage who can tell police about the room he just spent five days in.

    Ideas abound about how that radiation might spill the beans, and Hawking’s new revelation is just one contender. “The situation is not that there is a big problem, and here is the solution,” says Rovelli. “The situation is that there is a big problem, and there are a dozen solutions … none totally convincing, and now we have a new one.”

    Hawking’s big idea

    On August 25, as Hawking sat before the esteemed physicists, his voice played through the room’s speakers. “I propose that the information is stored not in the interior of the black hole, as one might expect, but on its boundary, the event horizon,” he said, “in the form of supertranslations of the horizon.”

    Translation: If you passed over the event horizon, you would leave an imprint on it. That imprint takes the form of, essentially, a hologram called a supertranslation—a two-dimensional representation of your three-dimensional parts—etched into the black hole’s exterior geometry. When Hawking radiation bubbles up, the event horizon leaves a similar imprint on that radiation. It’s like cosmic re-gifting. The Hawking radiation then streams back out into the universe, carrying the imprint, and the encoded information, with it. That code, though, is scrambled: If you fell into a black hole, we could not create your clone from it (sorry). But, cold comfort, your informational essence wouldn’t be eternally lost.

    The idea that information could be stamped onto a black hole’s event horizon was first proposed by Nobel Laureate Gerard ‘t Hooft, and supertranslations—as mathematical ideas—come from the 1960s. We don’t yet know enough about Hawking’s idea to detail how new and different it is.

    The problem with Hawking’s solution

    And that’s part of the problem: According to colleagues, the details of his “solution” feel fuzzy. “Two big questions are where the information from infalling stuff gets deposited, and how that information later gets transferred to stuff leaving the black hole,” says Steven Giddings, a physicist at the University of California, Santa Barbara.

    Those are two big questions—the biggest, most fundamental questions. It’s great that Hawking described the what of his idea, but, in science, the how is much more important. “What we need for a more detailed understanding is a more complete description of the mathematics … to see if they’ve really nailed the answer,” says Giddings. Rovelli agrees, stating, “The picture is very preliminary for the moment.”

    They weren’t the only two left scratching their heads. “In the conference, there were many world-class physicists, including Nobel Prize winners,” says Joe Polchinski, Giddings’ colleague at UC Santa Barbara. “I didn’t perceive much enthusiasm about the new idea. Everybody was interested, of course, but I couldn’t detect anybody that appeared convinced.”

    Polchinski, who has previously science-battled Hawking about black hole paradoxes, also pointed out a problem beyond the idea’s fuzziness: In Hawking’s scenario, information stays on the event horizon. But the information (using the previous example, you yourself) also falls into the black hole, meaning two copies of it would exist. “In quantum mechanics, information can’t be in two places,” Polchinski says, although he points out that Hawking may have found a way to evade this problem.

    Because Hawking’s black-hole revelations (as well as his proclamations about aliens and religion) receive public buzz and papers called “AdS/CFT without holography: A hidden dimension on the CFT side and implications for black-hole entropy” don’t, it may seem that his idea is totally novel. But it’s not. “From what we here understand, his suggestion builds on ideas that people have been tossing around recently,” says Giddings. Rovelli and Polchinski also point out its similarity to ’t Hooft’s 1990s ideas, although Hawking has added “some technical steps.”

    Hawking claims he, and co-conspirators Andrew Strominger of Harvard University and Malcolm Perry of Cambridge University, will leak more information in a paper in late September. If that paper throws around some convincing equations—what black-hole theorists require as evidence—the result could be a big deal. Until then, scientists are waiting to reserve judgment. “For the moment the theory is far too sketchy, in the manner it has been presented,” Rovelli says. “Let me put it this way: The big news is Hawking himself: his persona, his popular fame, the wonderful manner in which he communicate to the public and transmits enthusiasm to the public. This is fantastic and is his mastership. His physics is interesting, as many others’ are.”

    See the full article here.

    Please help promote STEM in your local schools.

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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 3:48 pm on August 14, 2015 Permalink | Reply
    Tags: , , Black Holes,   

    From NYT: “A Teensy Black Hole, Just 200,000 Miles Wide” 

    New York Times

    The New York Times

    August 14, 2015

    An artist’s illustration of the black hole at the center of dwarf galaxy RGG 118. Credit Chandra X-ray Observatory

    For a monster it’s pretty cute.

    Buried in a smush of stars known as RGG 118 — and noticeable only by a plaintive squeal of X-ray radiation — astronomers have discovered a new black hole. By the standards of normal life it’s not so small, a pit in space-time 200,000 miles across into which the equivalent of 50,000 suns have disappeared. But on a cosmic scale it’s not so big.

    Almost every galaxy, like the Milky Way, has a supermassive black hole millions or billions of times as massive as the sun sitting at it center. The bigger the galaxy, the more massive the black monster at its heart. Nobody knows why.

    The new black hole is the first one found in a dwarf galaxy. RGG 118, as it is elegantly named, is 340 million light-years away and about a hundredth the mass of our own Milky Way, whose central black hole weighs some 4 million suns.

    A team from the University of Michigan and Princeton, led by Vivienne Baldassarre, a Michigan graduate student, found and measured it by using NASA’s Chandra X-Ray Observatory and an optical telescope in Chile* to chart the speeds of stars and gas swirling around in the small galaxy.

    NASA Chandra Telescope

    Observing the behavior of such a teensy, so to speak, black hole, Ms. Baldassare and her colleagues hope, will help them understand where the monstrous black holes found in regular galaxies come from and how they grow so big. Some astronomers speculate that they are seeded from giant clouds of primordial gas, or the collapse of gargantuan stars that inhabited the dawn of time, and then grew by merging with other black holes as galaxies collided during the rough and tumble days of the early universe.

    The RGG 118 black hole is like finding a preteenager on the verge of all this. In the fullness of cosmic time, it could grow into a true monster.

    *optical telescope in Chile went unnamed in the article. Bad taste.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

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