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  • richardmitnick 10:50 am on July 4, 2015 Permalink | Reply
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    From NASA Blueshift: 

    NASA Blueshift
    NASA Blueshift

    July 4, 2015
    Sara Mitchell

    Happy Fourth of July to those of you that celebrate it! We couldn’t let the date slip by without presenting a little display of cosmic fireworks. We think you’ll find they’re much quieter than the earthly kind.

    We start with this 3D visualization of the nebula Gum 29 with the star cluster Westerlund 2 at its core. Young stars light up the gas around them as we sail through:

    Credit: NASA, ESA, G. Bacon, L. Frattare, Z. Levay, and F. Summers (Viz3D Team, STScI), and J. Anderson (STScI)

    In 1901, GK Persei captivated skygazers as it briefly appeared as the brightest object in the night sky. Now, astronomers understand that this light show was caused by a thermonuclear explosion on the surface of a white dwarf star. This recent image of GK Persei contains X-rays from Chandra (blue), optical data from NASA’s Hubble Space Telescope (yellow), and radio data from the National Science Foundation’s Very Large Array (pink).

    Image credit:
    X-ray: NASA/CXC/RIKEN/D.Takei et al; Optical: NASA/STScI; Radio: NRAO/VLA

    Supernova 1987A has put on a light show that has kept astronomers studying it for nearly 30 years. The vivid ring of material around the supernova, captured here by Hubble’s Advanced Camera for Surveys, was likely shed by the original star about 20,000 years before it exploded.

    Image credit: NASA, ESA, P. Challis and R. Kirshner (Harvard-Smithsonian Center for Astrophysics)

    Astronomers have nicknamed this planetary nebula “Eskimo Nebula” because they see a head wearing a parka hood. The gas clouds around this object composed the outer layers of a Sun-like star thousands of years ago. Now, a strong wind of particles from the central star is ejecting the unusually long filaments seen around it.

    Image credit: NASA/Andrew Fruchter (STScI)

    The Helix Nebula, another beautiful planetary nebula, has an eerie resemblance to a giant, all-seeing eye in this infrared image from the Spitzer Space Telescope. This object is what remains after the death of a small- to medium-sized star. The tiny white dot in the center is a white dwarf, the glowing red gas was blown out when the star died, and the outer gaseous layers are seen in brilliant blue and green.

    Image credit: NASA/JPL-Caltech/Univ.of Ariz.

    A stellar nursery is a surprisingly violent and energetic place. Astronomers have a chance to peer inside NGC 3603, a starburst cluster in the constellation Carina, because ultraviolet radiation and stellar winds have blown a cavity in the gas and dust surrounding these huge young stars.

    mage credit: NASA, ESA, R. O’Connell (University of Virginia), F. Paresce (National Institute for Astrophysics, Bologna, Italy), E. Young (Universities Space Research Association/Ames Research Center), the WFC3 Science Oversight Committee, and the Hubble Heritage Team (STScI/AURA)

    Enjoy and learn.

    See the full article here.

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    Blueshift is produced by a team of contributors in the Astrophysics Science Division at Goddard. Started in 2007, Blueshift came from our desire to make the fascinating stuff going on here every day accessible to the outside world.

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  • richardmitnick 10:17 am on July 4, 2015 Permalink | Reply
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    From Alex Millar at Quantum Diaries: “Why Dark Matter Exists: Believing Without Seeing” 

    Alex Millar, University of Melbourne

    The Milky Way rises over the Cerro Tololo Inter-American Observatory in northern Chile. The Dark Energy Survey operates from the largest telescope at the observatory, the 4-meter Victor M. Blanco Telescope (left). Photo courtesy of Andreas Papadopoulos

    CTIO Victor M Blanco 4m Telescope
    CTIO Victor M Blanco 4m Telescope interior
    CTIO Victor M Blanco 4 meter Telescope

    Dark Energy Survey

    DECam, built at FNAL, at Victor M. Blanco Telescope

    For decades physicists have been convinced that most of our universe is invisible, but how do we know that if we can’t see it? I want to explain the thought process that leads one to believe in a theory via indirect evidence. For those who want to see a nice summary of the evidence, check 81 Comments out. So this post isn’t 3000 words, I will simply say that either our theories of gravity are wrong, or the vast majority of the matter in our universe is invisible. That most of the matter in the universe is invisible, or “dark”, is actually well supported. Dark matter as a theory fits the data much better than modifications to gravity (with a couple of possible exceptions like mimetic dark matter). This isn’t necessarily surprising; frankly it would be a bit arrogant to assume that only matter similar to us exists. Particle physicists have known for a long time that not all particles are affected by all the fundamental forces. For example, the neutrino is invisible as it doesn’t interact with the electromagnetic force (or strong force, for that matter). So the neutrino is actually a form of dark matter, though it is much too quick and light to make up most of what we see.

    The standard cosmological model, the ΛCDM, has had tremendous success explaining the evolution of our universe. This is what most people refer to when they think of dark matter: the CDM stands for “cold dark matter”, and it is this consistency that allows us to explain observations from almost every cosmological epoch that is so compelling about dark matter. We see the effect of dark matter across the sky in the CMB, in the helium formed in primordial nucleosynthesis, in the very structure of the galaxies. We see dark matter a minute after the big bang, a million years, a billion years, and even today. Simply put, when you add in dark matter (and dark energy) almost the entirety of cosmological history makes sense. While there some elements that seem to be lacking in the ΛCDM model (small scale structure formation, core vs cusp, etc), these are all relatively small details that seem to have solutions in either simulating normal matter more accurately, or small changes to the exact nature of dark matter.

    Dark matter is essentially like a bank robber: the money is gone, but no-one saw the theft. Not knowing exactly who stole the money doesn’t mean that someone isn’t living it up in the Bahamas right now. The ΛCDM model doesn’t really care about the fine details of dark matter: things like its mass, exact interactions and formation are mostly irrelevant. To the astrophysicist, there are really two features that they require: dark matter cannot have strong interactions with normal matter (electromagnetic or strong forces), and dark matter must be moving relatively slowly (or “cold”). Anything that has these properties is called a dark matter “candidate” as it could potentially be the main constituent of dark matter. Particle physicists try to come up with these candidates, and hopefully find ways to test them. Ruling out a candidate is not the same as ruling out the idea of dark matter itself, it is just removing one of a hundred suspects.

    Being hard to find is a crucial property of dark matter. We know dark matter must be a slippery bastard, as it doesn’t interact via the electromagnetic or strong forces. In one sense, assuming we can discover dark matter in our lifetime is presumptuous: we are assuming that it has interactions beyond gravity. This is one of a cosmologist’s fondest hopes as without additional interactions we are screwed. This is because gravity is by far the weakest force. You can test this yourself – go to the fridge, and get a magnet. With a simple fridge magnet, weighing only a few grams, you can pick up a paperclip, overpowering the 6*10^24 kg of gravitational mass the earth possesses. Trying to get a single particle, weighing about the same as an atom, to show an appreciable effect only through gravity is ludicrous. That being said, the vast quantities of dark matter strewn throughout our universe have had a huge and very detectable gravitational impact. This gravitational impact has led to very successful and accurate predictions. As there are so many possibilities for dark matter, we try to focus on the theories that link into other unsolved problems in physics to kill two birds with one stone. While this would be great, and is well motivated, nature doesn’t have to take pity on us.

    So what do we look for in indirect evidence? Essentially, you want an observation that is predicted by your theory, but is very hard to explain without it. If you see an elephant shaped hole in your wall, and elephant shaped foot prints leading outside, and all your peanuts gone, you are pretty well justified in thinking that an elephant ate your peanuts. A great example of this is the acoustic oscillations in the CMB. These are huge sound waves, the echo of theCMB big bang in the primordial plasma.


    The exact frequency of this is related to the amount of matter in the universe, and how this matter interacts. Dark matter makes very specific predictions about these frequencies, which have been confirmed by measurements of the CMB. This is a key observation that modified gravity theories tend to have trouble explaining.

    The combination of the strong indirect evidence for dark matter, the relative simplicity of the theory and the lack of serious alternatives means that research into dark matter theories is the most logical path. That is not to say that alternatives should not be looked into, but to disregard the successes of dark matter is simply foolish. Any alternative must match the predictive power and observational success of dark matter, and preferably have a compelling reason for being ‘simpler’ or philosophically nicer then dark matter. While I spoke about dark matter, this is actually something that occurs all the time in science: natural selection, atomic theory and the quark model are all theories that have all been in the same position at one time or another. A direct discovery of dark matter would be fantastic, but is not necessary to form a serious scientific consensus. Dark matter is certainly mysterious, but ultimately not a particularly strange idea.

    Disclaimer: In writing this for a general audience, of course I have to make sacrifices. Technical details like the model dependent nature of cosmological observations are important, but really require an entire blog post to themselves to answer fully.

    See the full article here.

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  • richardmitnick 4:48 pm on July 3, 2015 Permalink | Reply
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    From DESY: “Unique Experiments at European X-Ray laser XFEL are go” 


    No Writer Credit

    New options for materials research, ultrafast chemistry and structural biology

    The Helmholtz Senate has given the green light for the Association’s involvement in a new kind of experimentation station at the European XFEL in Hamburg, Germany: the Helmholtz International User Consortia at the European XFEL will be funded with 30 million euro. The largest portion of the funding goes to the Helmholtz International Beamline for Extreme Fields (HIBEF), which will contribute essential components to the High-Energy Density Science (HED) instrument. Other funds go to the Serial Femtosecond Crystallography (SFX) user consortium and the h-RIXS measurement station for resonant inelastic scattering experiments. The Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and the research centre DESY had applied for the funding for the international user consortia.

    DESY Helmholtz Centres & Networks

    …The accelerator tunnel of European XFEL

    The goal is that, starting in 2018, the HIBEF infrastructures at HED will be used to conduct experiments under extreme conditions of high pressures, temperatures, or electromagnetic fields. The insights gleaned from these experiments will help improve models of planetary birth, among other things, and will also provide a basis for innovations in materials research and fusion technologies. “There is a great deal of interest in the joint extreme lab on the part of the international community,” says HZDR Scientific Director Prof. Roland Sauerbrey. “Some 100 institutes have already signaled their interest in our research facility.” The HZDR will be contributing a facility for materials research using high magnetic fields and a high power laser for ultrashort light pulses capable of heating electrons at the material surface to a temperature of several billion degrees Celsius. In the process, a special state of matter – a plasma, consisting of electrons and ions – is produced. An additional goal is that inside special diamond-anvil cells made by DESY, extremely high pressures of up to ten million bars and temperatures in the range of 1,500 to almost 10,000°C can be achieved.

    At the high-power laser DiPOLE, a contribution to HIBEF from Oxford University and the British science organization Science and Technology Facilities Council (STFC), matter is subjected to states of extreme pressure and temperatures on the order of several 1000°C. The states produced within the sample are similar to those found at the cores of planets. “We’re charting new scientific territory by paving the way for the types of experiments that up to now could not be performed,” says Prof. Helmut Dosch, chairman of the DESY Board of Directors, one of the consortium partners and a chief partner of the European XFEL.

    However, extreme conditions can only ever be produced for a few fractions of a second – which is why the extremely short and high-intensity X-ray laser flashes of the European XFEL lend themselves nicely to their analysis. “The new station allows us to replicate extreme conditions existing in outer space right here on Earth and examine them using X-ray laser light,” explains Prof. Massimo Altarelli, chairman of the European XFEL Management Board. “We are very pleased that potential users are highly committed to helping us build a top-notch European research facility.”

    The SFX user consortium will enable the determination of the atomic structure and function of biomolecules from extremely small crystals at the Single Particles, Clusters, and Biomolecules and Serial Femtosecond Crystallography (SPB/SFX) instrument. The structure of biomolecules is fundamentally important to their function, and decoding them is of essential importance to understanding the chemical foundations of life and numerous illnesses. Many biomolecules cannot be crystallized to a large enough extent to be successfully studied using conventional X-ray crystallography methods. With a high-throughput rate, the SPB/SFX instrument would enable such investigations. The international SFX user consortium is led by DESY and includes partners from Australia, Germany, the United Kingdom, Italy, Sweden, Slovakia, and the United States.

    With help from inelastic scattering experiments, scientists would be able to follow the steps of chemical reactions in near-real time, during which researchers would be able to observe individual types of atoms. The Heisenberg Resonant Inelastic X-Ray Scattering (h-RIXS) user consortium will contribute high-resolution spectrometers to the Spectroscopy and Coherent Scattering (SCS) instrument. The user consortium includes scientists from Germany, Finland, France, the United Kingdom, Italy, Sweden, and Switzerland.

    Geosciences, materials research, astrophysics, and plasma physics as well as structural biology and superfast chemical processes – the ultimate goal being to combine the European XFEL analytic tool with the most powerful magnetic fields currently available or experimental options of optical laser systems is to glean new insights into previously hidden processes within matter and materials. Thanks to the Helmholtz Senate’s 24 June 2015 decision, the Helmholtz stations will become reality. The final decision for the financial support remains now with the funding bodies on the federal and state level.

    See the full article here.

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    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

  • richardmitnick 12:11 pm on July 3, 2015 Permalink | Reply
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    From ESA: “Counting stars with Gaia” 

    European Space Agency

    3 July 2015
    No Writer Credit

    Stellar density map (Edmund Serpell)

    This image, based on housekeeping data from ESA’s Gaia satellite, is no ordinary depiction of the heavens. While the image portrays the outline of our Galaxy, the Milky Way, and of its neighbouring Magellanic Clouds, it was obtained in a rather unusual way.

    Large Magellanic Cloud

    Small Magellanic Cloud

    ESA Gaia satellite
    ESA Gaia Camera
    GAIA Camera

    As Gaia scans the sky to measure positions and velocities of a billion stars with unprecedented accuracy, for some stars it also determines their speed across the camera’s sensor. This information is used in real time by the attitude and orbit control system to ensure the satellite’s orientation is maintained with the desired precision.

    These speed statistics are routinely sent to Earth, along with the science data, in the form of housekeeping data. They include the total number of stars, used in the attitude-control loop, that is detected every second in each of Gaia’s fields of view.

    It is the latter – which is basically an indication of the density of stars across the sky – that was used to produce this uncommon visualisation of the celestial sphere. Brighter regions indicate higher concentrations of stars, while darker regions correspond to patches of the sky where fewer stars are observed.

    The plane of the Milky Way, where most of the Galaxy’s stars reside, is evidently the brightest portion of this image, running horizontally and especially bright at the centre. Darker regions across this broad strip of stars, known as the Galactic Plane, correspond to dense, interstellar clouds of gas and dust that absorb starlight along the line of sight.

    The Galactic Plane is the projection on the sky of the Galactic disc, a flattened structure with a diameter of about 100 000 light-years and a vertical height of only 1000 light-years.

    Beyond the plane, only a few objects are visible, most notably the Large and Small Magellanic Clouds, two dwarf galaxies orbiting the Milky Way, which stand out in the lower right part of the image.

    Annotated map

    A few globular clusters – large assemblies up to millions of stars held together by their mutual gravity – are also sprinkled around the Galactic Plane. Globular clusters, the oldest population of stars in the Galaxy, sit mainly in a spherical halo extending up to 100 000 light-years from the centre of the Milky Way.

    The globular cluster NGC 104 is easily visible in the image, to the immediate left of the Small Magellanic Cloud.

    NGC 104

    Other globular clusters are highlighted in an annotated version of this image.

    Interestingly, the majority of bright stars that are visible to the naked eye and that form the familiar constellations of the sky are not accounted for in this image because they are too bright to be used by Gaia’s control system. Similarly, the Andromeda galaxy – the largest galactic neighbour of the Milky Way – also does not stand out here.

    Counterintuitively, while Gaia carries a billion-pixel camera, it is not a mission aimed at imaging the sky: it is making the largest, most precise 3D map of our Galaxy, providing a crucial tool for studying the formation and evolution of the Milky Way.

    Gaia is an ESA mission to survey one billion stars in our Galaxy and local galactic neighbourhood in order to build the most precise 3D map of the Milky Way and answer questions about its origin and evolution.

    Gaia’s scientific operations begun on 25 July 2014 with the special scanning through a narrow region in the sky, while the normal scanning procedure was switched on a month later, on 25 August.

    The mission’s primary scientific product will be a catalogue with the position, motion, brightness and colour of the surveyed stars. An intermediate version of the catalogue will be released in 2016. In the meantime, Gaia’s observing strategy, with repeated scans of the entire sky, will allow the discovery and measurement of transient events across the sky.

    Acknowledgement: this image was prepared by Edmund Serpell, a Gaia Operations Engineer working in the Mission Operations Centre at ESA’s European Space Operations Centre in Darmstadt, Germany.

    This image is licenced under the Creative Commons Attribution-ShareAlike 3.0 IGO (CC BY-SA 3.0 IGO) licence.

    See the full article here.

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 11:19 am on July 3, 2015 Permalink | Reply
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    From Symmetry: “How do you solve a puzzle like neutrinos?” 


    June 30, 2015
    Lauren Biron

    When it comes to studying particles that zip through matter as though it weren’t even there, you use every method you can think of.

    Artwork by Sandbox Studio, Chicago with Ana Kova

    Sam Zeller sounds borderline embarrassed by scientists’ lack of understanding of neutrinos—particularly how much mass they have.

    “I think it’s a pretty sad thing that we don’t know,” she says. “We know the masses of all the particles except for neutrinos.” And that’s true even for the Higgs, which scientists only discovered in 2012.

    Ghostly neutrinos, staggeringly abundant and ridiculously aloof, have held onto their secrets long past when they were theorized in the 1930s and detected in the 1950s. Scientists have learned a few things about them:

    They come in three flavors associated with three other fundamental particles (the electron, muon and tau).
    They change, or oscillate, from one type to another.
    They rarely interact with anything, and trillions upon trillions stream through us every minute.
    They have a very small mass.

    But right now, there are still more questions than answers.

    Zeller, one of thousands of neutrino researchers around the world and co-spokesperson for the neutrino experiment MicroBooNE based at Fermilab, says the questions about neutrinos don’t stop at mass.

    FNAL MicroBooNE

    She writes down a shopping list of things physicists want to find out:

    Is one type of neutrino much heavier than the other two, or much lighter?
    What is the absolute mass of the neutrino?
    Are there more than three types of neutrinos?
    Do neutrinos and antineutrinos behave differently?
    Is the neutrino its own antiparticle?
    Is our picture of neutrinos correct?

    No single experiment can answer all of these questions. Instead, there are dozens of experiments looking at neutrinos from different sources, each contributing a piece to the puzzle. Some neutrinos stream unimpeded from far away, born in supernovae, the sun, the atmosphere or cosmic sources. Others originate closer to home, in the Earth, nuclear reactors, radioactive decays or particle accelerators. Their different birthplaces imbue them with different flavors and energies—a range so great, it spans at least 16 orders of magnitude. Armed with the knowledge of where and how to look, scientists are entering an exhilarating experimental time.

    “That’s why neutrino physics is so exciting right now,” Zeller says. “It’s not as if we’re shooting in the dark or we don’t know what we’re doing. Worldwide, we’re embarking on a program to answer these questions. That path will make use of these many different sources, and in the end you put it all together and hope the story makes sense.”


    Neutrinos from nuclear reactors

    The first confirmation that neutrinos were more than just a theory came from nuclear reactors, where neutrinos are produced in a process called beta decay. A team of scientists led by Clyde Cowan and Frederick Reines found neutrinos spewing in a steady stream from reactors at the Hanford Site in Washington and the Savannah River Plant in South Carolina between 1953 and 1959.

    Reactors have been useful for neutrino physics ever since, particularly because they produce only one kind of neutrino: electron antineutrinos. When studying the way particles change from one type to another, it’s invaluable to know exactly what you’re starting with.

    Reactor experiments such as KamLAND, which studied particles from 53 nuclear reactors in Japan, echoed results from projects examining solar and atmospheric neutrinos. All of them found that neutrinos changed flavor over time.


    “Once we know that neutrinos are oscillating, that gives us the strongest evidence that neutrinos are massive,” says Dan Dwyer, a scientist at Lawrence Berkeley National Laboratory and researcher on the international Daya Bay Reactor Neutrino Experiment based in China.

    Daya Bay
    Daya Bay

    Such projects now look for the way neutrinos change and for hints about their relative masses.

    Because reactor experiments allow for precision, they’re also ideal to hunt for a fourth type of particle—the yet unobserved sterile neutrino, thought to interact only through gravity.


    Neutrinos from accelerators

    Reactor neutrinos aren’t the only way to look for additional neutrinos. That’s where the powerhouse of neutrino research—the accelerator—comes in.

    Scientists can use a beam of easier-to-control particles such as protons to create a beam of neutrinos.

    First, they accelerate the protons and smash them into a target. The energy released in this collision converts to mass in the form of a flood of new massive particles. Those particles decay into less massive particles, including neutrinos.

    Before the massive particles decay, scientists use magnets to focus them into a beam. Afterward, they use blocking material to skim off unwanted bits while the neutrinos—which can pass through a light-year of lead without even noticing it’s there—flow freely through.

    Neutrino beams from accelerators are typically made of muon neutrinos and antineutrinos, but the experiments that use accelerators split into two main groups: short-baseline experiments, which look at oscillations over smaller distances, and long-baseline experiments, which study neutrinos that have traveled over hundreds of miles.

    Both types of experiments look at how neutrinos oscillate. At short distances, neutrinos are less likely to have changed flavors, though the influence of undiscovered new particles or forces might affect that rate. At long distances, neutrinos are more likely to have changed after traveling for a few milliseconds at nearly the speed of light. Oscillation patterns can give scientists clues as to the masses of the different types of neutrinos.

    Oscillation studies over long distances, like Japan’s T2K experiment or the United States’ NOvA experiment and proposed DUNE experiment, can help researchers find how neutrinos relate to antineutrinos. One method is to search for charge parity violation.



    This complicated-sounding term essentially asks whether matter and antimatter can pull off “the old switcheroo”—that is, whether the universe treats matter and antimatter particles identically. If the oscillations of neutrinos are fundamentally different from the oscillations of antineutrinos, then CP is broken.

    Scientists already know that CP is violated for one major building block of the universe: the quarks. Does the same happen for the other major family, the leptons? Neutrinos might hold the key.


    Studying neutrinos without neutrinos

    It’s odd that one of the most important questions regarding neutrinos can be answered only by looking for a process apparently lacking in neutrinos.

    In neutrinoless double beta decay, a particle would decay into electrons and neutrinos, but the neutrinos would annihilate one another within the nucleus.

    “If you see it, it tells you that neutrinos are different in a fundamental way,” says Boris Kayser, a theorist at Fermilab.

    Neutrinoless double beta decay would occur only if neutrinos and their antiparticles were one and the same. No other fundamental particle of matter has this property.

    “Neutrinos are very special,” Kayser says. “It could be that they violate rules that other particles don’t violate.”

    Several experiments worldwide are under way to search for this process, with future generations planned.

    A different experiment, KATRIN, hopes to find the masses of the neutrinos by looking at particular electrons. As a radioactive kind of hydrogen decays, it spits out an antineutrino and a partner electron. Scientists will use the world’s largest spectrometer to measure the energy of these electrons to learn about the neutrino.

    KATRIN Experiment



    Unperturbed by magnetism or mass in their paths, neutrinos are perhaps the ultimate messengers of the universe. Once found, the particles point back to their origins, places scientists can’t otherwise see. Investigating these neutrinos provides insight into the particles themselves and is a useful way to probe the unknown.

    Take the Earth as an example. Scientists can use detectors to capture geoneutrinos, typically low-energy electron antineutrinos, to learn about the composition of our planet without trying to drill miles below the surface. Because we’ve learned that neutrinos are born of particle decay, the number of geoneutrinos tells researchers how much potassium, thorium and uranium lurk below, heating our world.


    Solar neutrinos

    Neutrinos are also created in processes in the sun. But when Ray Davis built a solar neutrino detector filled with dry cleaning fluid, his experiment picked up only a third of the predicted neutrinos.

    This solar neutrino problem hinted that we didn’t understand our sun; in reality, we didn’t understand neutrinos. Solar neutrino experiments after Davis’ showed that neutrinos from the sun were changing flavor, and a reactor experiment later confirmed that the flavor change was caused by neutrino oscillation.

    Modern solar neutrino experiments such as Italy’s Borexino provide insight into the core of the sun and help put limits on sterile neutrinos.

    Others, like Japan’s Super-Kamiokande detector, can look at how solar neutrinos change when traveling through the earth versus neutrinos oscillating primarily in the vacuum of space.

    Super-Kamiokande experiment Japan

    “The reason that’s important is that if the neutrino interacts with matter in new, unknown ways, which is possible, then this effect would be changed,” says Josh Klein, professor of physics at the University of Pennsylvania. “It’s a very sensitive measure of new physics.”


    Cosmic neutrinos

    Cosmic neutrinos illuminate powerful phenomena occurring within our galaxy and beyond. Massive extragalactic neutrino hunting experiments, such as the IceCube experiment that sprawls across a cubic kilometer of ice in Antarctica, can find neutrinos that have oscillated over much longer distances than we can test with accelerators.

    ICECUBE neutrino detector
    IceCube neutrino detector interior

    “We see neutrinos [with energies] from below 10 [billion electronvolts] to above a thousand [trillion electronvolts],” says Francis Halzen, physicist at the University of Wisconsin, Madison, and leader of IceCube. “Nobody has ever built something that covers this energy range of particles.”

    Giant neutrino detectors like this one can look for sterile neutrinos and gather information on oscillations and mass hierarchy.

    They’re also useful for understanding dark matter and supernovae, analyzing atmospheric neutrinos that form when cosmic rays hit our atmosphere and telling other astronomers where to point their telescopes if neutrinos from a supernova burst hit. Physicists learn properties of neutrinos, but the neutrinos in turn unlock secrets of the universe.

    “Whenever we have made a picture of the universe in a different wavelength region of light, we have always seen things we didn’t expect,” Halzen says. “We’re doing now what astronomers have been doing for decades: looking at the sky in different ways.”

    Neutrinos matter for matter

    At the end of the day, why go to all this trouble for such a tiny particle? In addition to helping scientists probe the interior of the Earth or the far-off corners of the cosmos, neutrinos could hold the key to why matter exists today.

    Scientists know that antimatter and matter are produced in equal parts and should ultimately have annihilated one another, leaving a dark and empty universe. But here we stand, matter in all its glory.

    Sometime early in the universe’s history, an imbalance arose and shifted the scales toward a matter-dominated universe. If physicists find that neutrinos have certain characteristics—including CP violation—it could help explain why the universe turned out the way it did.

    “They’re the most abundant massive particle in the universe,” Zeller says. “If you find out something weird about neutrinos, it’s bound to tell you something about how the universe evolved or how it came to be the way we observe today.”

    See the full article here.

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    Symmetry is a joint Fermilab/SLAC publication.

  • richardmitnick 11:29 am on June 27, 2015 Permalink | Reply
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    From Subaru: “Unexpectedly Little Black-hole Monsters Rapidly Suck up Surrounding Matter” 



    June 25, 2015
    No Writer Credit

    Using the Subaru Telescope, researchers at the Special Astrophysical Observatory in Russia and Kyoto University in Japan have found evidence that enigmatic objects in nearby galaxies – called ultra-luminous X-ray sources (ulx’s) – exhibit strong outflows that are created as matter falls onto their black holes at unexpectedly high rates. The strong outflows suggest that the black holes in these ULXs must be much smaller than expected. Curiously, these objects appear to be “cousins” of SS 433, one of the most exotic objects in our own Milky Way Galaxy.


    The team’s observations help shed light on the nature of ULXs, and impact our understanding of how supermassive black holes in galactic centers are formed and how matter rapidly falls onto those black holes (Figure 1).

    Figure 1: Multi-color optical image around the ULX “X-1″ (indicated by the arrow) in the dwarf galaxy Holmberg II, located in the direction of the constellation Ursa Major, at a distance of 11 million light-years. The image size corresponds to 1,100 × 900 light-years at the galaxy. The red color represents spectral line emission from hydrogen atoms. (Credit: Special Astrophysical Observatory/Hubble Space Telescope)

    X-ray observations of nearby galaxies have revealed these exceptionally luminous sources at off-nuclear positions that radiate about million times higher power than the Sun. The origins of ULXs have been a subject of heated debate for a long time. The basic idea is that a ULX is a close binary system consisting of a black hole and a star. As matter from the star falls onto the black hole, an accretion disk forms around the black hole. As the gravitational energy of the material is released, the innermost part of the disk is heated up to a temperature higher than 10 million degrees, which causes it to emit strong X-rays.

    The unsolved key question about these objects asks: what is the mass of the black hole in these bright objects? ULXs are typically more than a hundred times more luminous than known black hole binaries in the Milky Way, whose black hole masses are at most 20 times the mass of the Sun.

    There are two different black hole scenarios proposed to explain these objects: (1) they contain very “big” black holes that could be more than a thousand times more massive than the Sun (Note 1), or (2) they are relatively small black holes, “little monsters” with masses no more than a hundred times that of the Sun, that shine at luminosities exceeding theoretical limits for standard accretion (called ” (or super-Eddington) accretion,” Note 2). Such supercritical accretion is expected to produce powerful outflow in a form of a dense disk wind.

    To understand which scenario explains the observed ULXs researchers observed four objects: Holmberg II X-1, Holmberg IX X-1, NGC 4559 X-7, NGC 5204 X-1, and took high-quality spectra with the FOCAS instrument on Subaru Telescope for four nights. Figure 1 shows an optical multi-color image toward Holmberg II X-1 as observed with Hubble Space Telescope. The object X-1, indicated by the arrow, is surrounded by a nebula (colored in red), which is most likely the gas heated by strong radiation from the ULX.

    The team discovered a prominent feature in the optical spectra of all the ULXs observed (Figure 2). It is a broad emission line from helium ions, which indicates the presence of gas heated to temperatures of several tens of thousands of degrees in the system. In addition, they found that the width of the hydrogen line, which is emitted from cooler gas (with a temperature of about 10,000 K), is broader than the helium line. The width of a spectral line reflects velocity dispersion of the gas and shows up due to the Doppler effect caused by a distribution of the velocities of gas molecules. These findings suggest that the gas must be accelerated outward as a wind from either the disk or the companion star and that it is cooling down as it escapes.

    Figure 2: Optical spectra of the four ULXs observed with the Subaru Telescope (from upper to lower, Holmberg II X-1, Holmberg IX X-1, NGC 4559 X-7, NGC 5204 X-1). He II and Hα denote the spectral lines from helium ions and from hydrogen atoms, respectively. (Credit: Kyoto University)

    Distant ULXs and a Similar Mysterious Object in the Milky Way

    The activity of these ULXs in distant galaxies is very similar to a mysterious object in our own Milky Way. The team noticed that the same line features are also observed at SS 433, a close binary consisting of an A-type star and most probably a black hole with a mass less than 10 times that of the Sun.


    SS 433 is famous for its persistent jets with a velocity of 0.26 times the speed of light. It is the only confirmed system that shows supercritical accretion (that is, an excessive amount of accretion that results in a very powerful outflow). By contrast, such features have not been observed from “normal” black hole X-ray binaries in the Milky Way where sub-critical accretion takes place.

    After carefully examining several possibilities, the team concluded that huge amounts of gas are rapidly falling onto “little monster” black holes in each of these ULXs, which produces a dense disk wind flowing away from the supercritical accretion disk. They suggest that “bona-fide” ULXs with luminosities of about million times that of the Sun must belong to a homogeneous class of objects, and SS 433 is an extreme case of the same population. In these, even though the black hole is small, very luminous X-ray radiation is emitted as the surrounding gas falls onto the disk at a huge rate.

    Figure 3 is a schematic view of the ULXs (upper side) and SS 433 (lower side). If the system is observed from a vertical direction, it’s clear that the central part of the accretion disk emits intense X-rays. If SS 433 were observed in the same direction, it would be recognized as the brightest X-ray source in the Milky Way. In reality, since we are looking at SS 433 almost along the disk plane, our line-of-sight view towards the inner disk is blocked by the outer disk. The accretion rate is inferred to be much larger in SS 433 than in the ULXs, which could explain the presence of persistent jets in SS 433.

    Figure 3: Schematic view of ULXs (looking from upper side) and SS 433 (looking from left side). Strong X-rays are emitted from the inner region of the supercritical accretion disk. Powerful winds are launched from the disk, which eventually emit spectral lines of helium ions and hydrogen atoms. (Credit: Kyoto University)

    Such “supercritical accretion” is thought to be a possible mechanism in the formation of supermassive black holes at galactic centers in very short time periods (which are observed very early in cosmic time). The discovery of these phenomena in the nearby universe has significant impacts on our understanding of how supermassive black holes are formed and how matter rapidly falls onto them.

    There are still some remaining questions: What are the typical mass ranges of the black holes in ULXs? In what conditions can steady baryonic jets as observed in SS 433 be produced? Dr. Yoshihiro Ueda, a core member of the team, expresses his enthusiasm for future research in this area. “We would like to tackle these unresolved problems by using the new X-ray observations by [jAXA]ASTRO-H, planned to be launched early next year, and by more sensitive future X-ray satellites, together with multi-wavelength observations of ULXs and SS 433,” he said.

    JAXA ASTRO-H telescope

    This work has been published online in Nature Physics on 2015 June 1 (Fabrika et al. 2015, Supercritical Accretion Discs in Ultraluminous X-ray Sources and SS 433, 10.1038/nphys3348). The research was supported by the Japan Society for the Promotion of Science’s KAKENHI Grant number 26400228.


    Sergei Fabrika (Special Astrophysical Observatory, Russia; Kazan Federal University, Russia)
    Yoshihiro Ueda (Department of Astronomy, Kyoto University, Japan)
    Alexander Vinokurov (Special Astrophysical Observatory, Russia)
    Olga Sholukhova (Special Astrophysical Observatory, Russia)
    Megumi Shidatsu (Department of Astronomy, Kyoto University, Japan)


    Generally, black holes with masses between about 100 and about 100,000 times that of the Sun are called “intermediate-mass black holes,” although there is no strict definition for the mass range.
    In a spherically symmetric case, matter cannot fall onto a central object when the radiation pressure exceeds the gravity. This luminosity is called the Eddington limit, which is proportional to the mass of the central object. When matter is accreted at rates higher than that corresponding to the Eddington limit, it is called “supercritical (or super-Eddington) accretion.” In the case of non-spherical geometry, such as disk accretion, supercritical accretion may happen.

    See the full article here.

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    The National Astronomical Observatory of Japan (NAOJ) is an astronomical research organisation comprising several facilities in Japan, as well as an observatory in Hawaii. It was established in 1988 as an amalgamation of three existing research organizations – the Tokyo Astronomical Observatory of the University of Tokyo, International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University.

    In the 2004 reform of national research organizations, NAOJ became a division of the National Institutes of Natural Sciences.

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    Okayama Astrophysical Observatory

    The National Astronomical Observatory of Japan (NAOJ) is an astronomical research organisation comprising several facilities in Japan, as well as an observatory in Hawaii. It was established in 1988 as an amalgamation of three existing research organizations – the Tokyo Astronomical Observatory of the University of Tokyo, International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University.

    In the 2004 reform of national research organizations, NAOJ became a division of the National Institutes of Natural Sciences.

  • richardmitnick 10:44 am on June 27, 2015 Permalink | Reply
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    From Don Lincoln at FNAL: “Gravitational Lensing” 

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

    FNAL Don Lincoln
    Don Lincoln

    In a long line of intellectual triumphs, [Albert] Einstein’s theory of general relativity was his greatest and most imaginative. It tells us that what we experience as gravity can be most accurately described as the bending of space itself. This idea leads to consequences, including gravitational lensing, which is caused by light traveling in this curved space. This is works in a way analogous to a lens (and hence the name). In this video, Fermilab’s Dr. Don Lincoln explains a little general relativity, a little gravitational lensing, and tells us how this phenomenon allows us to map out the matter of the entire universe, including the otherwise-invisible dark matter.

    Watch, enjoy, learn.

    See the full article here.

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

  • richardmitnick 1:45 pm on June 25, 2015 Permalink | Reply
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    From Symmetry: “Exploring dark energy with robots” 


    June 25, 2015
    Glenn Roberts Jr.

    The Dark Energy Spectroscopic Instrument will produce a 3-D space map using a ‘hive’ of robots.

    Courtesy of NOAO

    Five thousand pencil-shaped robots, densely nested in a metal hive, whir to life with a precise, dizzying choreography. Small U-shaped heads swivel into a new arrangement in a matter of seconds.

    This preprogrammed routine will play out about four times per hour every night at the Dark Energy Spectroscopic Instrument. The robots of DESI will be used to produce a 3-D map of one-third of the sky. This will help DESI fulfill its primary mission of investigating dark energy, a mysterious force thought to be causing the acceleration of the expansion of the universe.

    DESI Dark Energy Spectroscopic Instrument

    The tiny robots will be arranged in 10 wedge-shaped metal “petals” that together form a cylinder about 2.6 feet across. They will maneuver the ends of fiber-optic cables to point at sets of galaxies and other bright objects in the universe. DESI will determine their distance from Earth based on the light they emit.

    DESI’s robots are in development at Lawrence Berkeley National Laboratory, the lead in the DESI collaboration, and at the University of Michigan.

    Courtesy of: DESI collaboration

    The robots—each about 8 millimeters wide in their main section and 8 inches long—will be custom-built around commercially available motors measuring just 4 millimeters in diameter. This type of precision motor, at this size, became commercially available in 2013 and is now manufactured by three companies. The motors have found use in medical devices such as insulin pumps, surgical robots and diagnostic tools.

    At DESI, the robots will automate what was formerly a painstaking manual process used at previous experiments. At the Baryon Oscillation Spectroscopic Survey, or BOSS, which began in 2009, technicians must plug 1000 fibers by hand several times each day into drilled metal plates, like operators plugging cables into old-fashioned telephone switchboards.

    “DESI is exciting because all of that work will be done robotically,” says Risa Wechsler, a co-spokesperson for DESI and an associate professor of the Kavli Institute for Particle Astrophysics and Cosmology, a joint institute of Stanford University and SLAC National Accelerator Laboratory. Using the robots, DESI will be able to redirect all of its 5000 fibers in an elaborate dance in less than 30 seconds (see video).

    “DESI definitely represents a new era,” Wechsler says.

    In addition to precisely measuring the color of light emitted by space objects, DESI will also measure how the clustering of galaxies and quasars, which are very distant and bright objects, has evolved over time. It will calculate the distance for up to 25 million space objects, compared to the fewer than 2 million objects examined by BOSS.

    The robots are designed to both collect and transmit light. After each repositioning of fibers, a special camera measures the alignment of each robot’s fiber-optic cable within thousandths of a millimeter. If the robots are misaligned, they are automatically individually repositioned to correct the error.

    Each robot has its own electronics board and can shut off and turn on independently, says Joe Silber, an engineer at Berkeley Lab who manages the system that includes the robotic array.

    In seven successive generations of prototype designs, Silber has worked to streamline and simplify the robots, trimming down their design from 60 parts to just 18. “It took a long time to really understand how to make these things as cheap and simple as possible,” he says. “We were trying not to get too clever with them.”

    The plan is for DESI to begin a 5-year run at Kitt Peak National Observatory near Tucson, Arizona, in 2019. Berkeley and Michigan scientists plan to build a test batch of 500 robots early next year, and to build the rest in 2017 and 2018.

    See the full article here.

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    Symmetry is a joint Fermilab/SLAC publication.

  • richardmitnick 9:31 am on June 25, 2015 Permalink | Reply
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    From ESA: “Monster black hole wakes up after 26 years” 

    European Space Agency

    Black hole with stellar companion

    25 June 2015
    No Writer Credit

    Over the past week, ESA’s Integral satellite has been observing an exceptional outburst of high-energy light produced by a black hole that is devouring material from its stellar companion.

    ESA Integral

    X-rays and gamma rays point to some of the most extreme phenomena in the Universe, such as stellar explosions, powerful outbursts and black holes feasting on their surroundings.

    In contrast to the peaceful view of the night sky we see with our eyes, the high-energy sky is a dynamic light show, from flickering sources that change their brightness dramatically in a few minutes to others that vary on timescales spanning years or even decades.

    On 15 June 2015, a long-time acquaintance of X-ray and gamma ray astronomers made its comeback to the cosmic stage: V404 Cygni, a system comprising a black hole and a star orbiting one another. It is located in our Milky Way galaxy, almost 8000 light-years away in the constellation Cygnus, the Swan.

    In this type of binary system, material flows from the star towards the black hole and gathers in a disc, where it is heated up, shining brightly at optical, ultraviolet and X-ray wavelengths before spiralling into the black hole.

    First signs of renewed activity in V404 Cygni were spotted by the Burst Alert Telescope on NASA’s Swift satellite, detecting a sudden burst of gamma rays, and then triggering observations with its X-ray telescope.

    NASA SWIFT Telescope

    Soon after, MAXI (Monitor of All-sky X-ray Image), part of the Japanese Experiment Module on the International Space Station, observed an X-ray flare from the same patch of the sky.

    These first detections triggered a massive campaign of observations from ground-based telescopes and from space-based observatories, to monitor V404 Cygni at many different wavelengths across the electromagnetic spectrum. As part of this worldwide effort, ESA’s Integral gamma-ray observatory started monitoring the out-bursting black hole on 17 June.

    Integral image before and after the outburst

    “The behaviour of this source is extraordinary at the moment, with repeated bright flashes of light on time scales shorter than an hour, something rarely seen in other black hole systems,” comments Erik Kuulkers, Integral project scientist at ESA.

    “In these moments, it becomes the brightest object in the X-ray sky – up to fifty times brighter than the Crab Nebula, normally one of the brightest sources in the high-energy sky.”

    The V404 Cygni black hole system has not been this bright and active since 1989, when it was observed with the Japanese X-ray satellite Ginga and high-energy instruments on board the Mir space station.

    “The community couldn’t be more thrilled: many of us weren’t yet professional astronomers back then, and the instruments and facilities available at the time can’t compare with the fleet of space telescopes and the vast network of ground-based observatories we can use today. It is definitely a ‘once in a professional lifetime’ opportunity,” adds Kuulkers.

    Integral light curve

    The 1989 outburst of V404 Cygni was crucial in the study of black holes. Until then, astronomers knew only a handful of objects that they thought could be black holes, and V404 Cygni was one of the most convincing candidates.

    A couple of years after the 1989 outburst, once the source had returned to a quieter state, the astronomers were able to see its companion star, which had been outshone by the extreme activity. The star is about half as massive as the Sun, and by studying the relative motion of the two objects in the binary system, it was determined that the companion must be a black hole, about twelve times more massive than the Sun.

    At the time, the astronomers also looked back at archival data from optical telescopes over the twentieth century, finding two previous outbursts, one in 1938 and another one in 1956.

    These peaks of activity, which occur every two to three decades, are likely caused by material slowly piling up in the disc surrounding the black hole, until eventually reaching a tipping point that dramatically changes the black hole’s feeding routine for a short period.

    “Now that this extreme object has woken up again, we are all eager to learn more about the engine that powers the outburst we are observing,” says Carlo Ferrigno from the Integral Science Data Centre at the University of Geneva, Switzerland.

    “As coordinators of Integral operations, Enrico Bozzo and I received a text message at 01:30 am on 18 June from our burst alert system, which is designed to detect gamma-ray bursts in the Integral data. In this case, it turned out to be ‘only’ an exceptional flare since Integral was observing this incredible black hole: definitely a good reason to be woken up in the middle of the night!”

    Since the first outburst detection on 15 June by the Swift satellite, V404 Cygni has remained very active, keeping astronomers extremely busy. Over the past week, several teams around the world published over twenty Astronomical Telegrams and other official communications, sharing the progress of the observations at different wavelengths.

    This exciting outburst has also been discussed by astronomers attending the European Week of Astronomy and Space Science conference this week in Tenerife, sharing information on observations that have been made in the past few days.

    Integral too has been observing this object continuously since 17 June, except for some short periods when it was not possible for operational reasons. The X-ray data show huge variability, with intense flares lasting only a couple of minutes, as well as longer outbursts over time scales of a few hours. Integral also recorded a huge emission of gamma rays from this frenzied black hole.

    Because different components of a black-hole binary system emit radiation at different wavelengths across the spectrum, astronomers are combining high-energy observations with those made at optical and radio wavelengths in order to get a complete view of what is happening in this unique object.

    “We have been observing V404 Cygni with the Gran Telescopio Canarias, which has the largest mirror currently available for optical astronomy,” explains Teo Muñoz-Darias from the Instituto de Astrofísica de Canarias in Tenerife, Spain.

    Grand Telescope de Canaries
    Gran Telescope de Canaries interior
    Gran Telescopio Canarias

    Using this 10.4-m telescope located on La Palma, the astronomers can quickly obtain high quality spectra, thus probing what happens around the black hole on short time scales.

    “There are many features in our spectra, showing signs of massive outflows of material in the black hole’s environment. We are looking forward to testing our current understanding of black holes and their feeding habits with these rich data,” adds Muñoz-Darias.

    Radio astronomers all over the world are also joining in this extraordinary observing campaign. The first detection at these long wavelengths was made shortly after the first Swift alert on 15 June with the Arcminute Microkelvin Imager from the Mullard Radio Astronomy Observatory near Cambridge, in the UK, thanks to the robotic mode of this telescope.

    Arcminute Microkelvin Imager
    Arcminute Microkelvin Imager

    Like the data at other wavelengths, these radio observations also exhibit a continuous series of extremely bright flares. Astronomers will exploit them to investigate the mechanisms that give rise to powerful jets of particles, moving away at velocities close to the speed of light, from the black hole’s accretion disc.

    There are only a handful of black-hole binary systems for which data have been collected simultaneously at many wavelengths, and the current outburst of V404 Cygni offers the rare chance to gather more observations of this kind. Back in space, Integral has a full-time job watching the events unfold.

    “We have been devoting all of Integral’s time to observe this exciting source for the past week, and we will keep doing so at least until early July,” comments Peter Kretschmar, ESA Integral mission manager.

    “The observations will soon be made available publicly, so that astronomers across the world can exploit them to learn more about this unique object. It will also be possible to use Integral data to try and detect polarisation of the X-ray and gamma ray emission, which could reveal more details about the geometry of the black hole accretion process. This is definitely material for the astrophysics textbooks for the coming years.”

    Notes for Editors

    The International Gamma-ray Astrophysics Laboratory Integral was launched on 17 October 2002. It is an ESA project with the instruments and a science data centre funded by ESA Member States (especially the Principal Investigator countries: Denmark, France, Germany, Italy, Spain and Switzerland), and with the participation of Russia and the USA. The mission is dedicated to spectroscopy (E/∆E = 500) and imaging (angular resolution: 12 arcmin FWHM) of celestial gamma-ray sources in the energy range 15 keV to 10 MeV with concurrent source monitoring in the X-ray (3–35 keV) and optical (V-band, 550 nm) wavelengths.

    See the full article here.

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 5:19 am on June 25, 2015 Permalink | Reply
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    From ESO: “Giant Galaxy is Still Growing” 

    European Southern Observatory

    25 June 2015
    Alessia Longobardi
    Max-Planck-Institut für extraterrestrische Physik
    Garching bei München, Germany
    Tel: +49 89 30000 3022
    Email: alongobardi@mpe.mpg.de

    Magda Arnaboldi
    Garching bei München, Germany
    Tel: +49 89 3200 6599
    Email: marnabol@eso.org

    Ortwin Gerhard
    Max-Planck-Institut für extraterrestrische Physik
    Garching bei München, Germany
    Tel: +49 89 30000 3539
    Email: gerhard@mpe.mpg.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


    New observations with ESO’s Very Large Telescope have revealed that the giant elliptical galaxy Messier 87 has swallowed an entire medium-sized galaxy over the last billion years. For the first time a team of astronomers has been able to track the motions of 300 glowing planetary nebulae to find clear evidence of this event and also found evidence of excess light coming from the remains of the totally disrupted victim.

    Astronomers expect that galaxies grow by swallowing smaller galaxies. But the evidence is usually not easy to see — just as the remains of the water thrown from a glass into a pond will quickly merge with the pond water, the stars in the infalling galaxy merge in with the very similar stars of the bigger galaxy leaving no trace.

    But now a team of astronomers led by PhD student Alessia Longobardi at the Max-Planck-Institut für extraterrestrische Physik, Garching, Germany has applied a clever observational trick to clearly show that the nearby giant elliptical galaxy Messier 87 merged with a smaller spiral galaxy in the last billion years.

    “This result shows directly that large, luminous structures in the Universe are still growing in a substantial way — galaxies are not finished yet!” says Alessia Longobardi. “A large sector of Messier 87’s outer halo now appears twice as bright as it would if the collision had not taken place.”

    Messier 87 lies at the centre of the Virgo Cluster of galaxies.

    This deep image of the Virgo Cluster obtained by Chris Mihos and his colleagues using the Burrell Schmidt telescope shows the diffuse light between the galaxies belonging to the cluster. North is up, east to the left. The dark spots indicate where bright foreground stars were removed from the image. Messier 87 is the largest galaxy in the picture (lower left).

    Case Western Burrell Schmidt telescope Kitt Peak
    Western Burrell Schmidt telescope Kitt Peak

    It is a vast ball of stars with a total mass more than a million million times that of the Sun, lying about 50 million light-years away.

    Rather than try to look at all the stars in Messier 87 — there are literally billions and they are too faint and numerous be studied individually — the team looked at planetary nebulae, the glowing shells around ageing stars [1]. Because these objects shine very brightly in a specific hue of aquamarine green, they can be distinguished from the surrounding stars. Careful observation of the light from the nebulae using a powerful spectrograph can also reveal their motions [2].

    Just as the water from a glass is not visible once thrown into the pond — but may have caused ripples and other disturbances that can be seen if there are particles of mud in the water — the motions of the planetary nebulae, measured using the FLAMES spectrograph on the Very Large Telescope, provide clues to the past merger.


    “We are witnessing a single recent accretion event where a medium-sized galaxy fell through the centre of Messier 87, and as a consequence of the enormous gravitational tidal forces, its stars are now scattered over a region that is 100 times larger than the original galaxy!” adds Ortwin Gerhard, head of the dynamics group at the Max-Planck-Institut für extraterrestrische Physik, Garching, Germany, and a co-author of the new study.

    The team also looked very carefully at the light distribution in the outer parts of Messier 87 and found evidence of extra light coming from the stars in the galaxy that had been pulled in and disrupted. These observations have also shown that the disrupted galaxy has added younger, bluer stars to Messier 87, and so it was probably a star-forming spiral galaxy before its merger.

    “It is very exciting to be able to identify stars that have been scattered around hundreds of thousands of light-years in the halo of this galaxy — but still to be able to see from their velocities that they belong to a common structure. The green planetary nebulae are the needles in a haystack of golden stars. But these rare needles hold the clues to what happened to the stars,” concludes co-author Magda Arnaboldi (ESO, Garching, Germany).

    [1] Planetary nebulae form as Sun-like stars reach the ends of their lives, and they emit a large fraction of their energy in just a few spectral lines, the brightest of which is in the green part of the spectrum. Because of this, they are the only single stars whose motions can be measured at Messier 87’s distance of 50 million light-years from Earth. They behave like beacons of green light and as such they tell us where they are and at what velocity they are travelling.

    [2] These planetary nebulae are still very faint and need the full power of the Very Large Telescope to study them: the light emitted by a typical planetary nebula in the halo of the Messier 87 galaxy is equivalent to two 60-watt light bulbs on Venus as seen from Earth.

    The motions of the planetary nebulae along the line of sight towards or away from Earth lead to shifts in the spectral lines, as a result of the Doppler effect. These shifts can be measured accurately using a sensitive spectrograph and the velocity of the nebulae deduced.
    More information

    This research was presented in a paper entitled The build-up of the cD halo of M87 — evidence for accretion in the last Gyr, by A. Longobardi et al., to appear in the journal Astronomy & Astrophysics Letters on 25 June 2015.

    This work was also presented at the annual conference of the European Astronomical Society, EWASS 2015, which is being held in La Laguna, Tenerife, at the same time.

    The team is composed of A. Longobardi (Max-Planck-Institut für extraterrestrische Physik, Garching, Germany), M. Arnaboldi (ESO, Garching, Germany), O. Gerhard (Max-Planck-Institut für extraterrestrische Physik, Garching, Germany) and J.C. Mihos (Case Western University, Cleveland, Ohio, 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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