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  • richardmitnick 4:36 am on February 12, 2016 Permalink | Reply
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    From LIGO: “Gravitational Waves Detected 100 Years After Einstein’s Prediction” 

    MIT Caltech Caltech Advanced aLigo new bloc

    MIT Caltech Advanced aLIGO

    Cornell SXS teamTwo merging black holes simulation

    Gravitational Waves Detected 100 Years After Einstein’s Prediction

    February 11, 2016

    Caltech
    Kathy Svitil
    Director of News and Content Strategy
    626-676-7628 (cell)
    ksvitil@caltech.edu

    MIT
    Kimberly Allen
    Director of Media Relations
    Deputy Director, MIT News Office
    617-253-2702 (office)
    617-852-6094 (cell)
    allenkc@mit.edu

    NSF
    Ivy Kupec
    Media Officer
    703-292-8796 (Office)
    703-225-8216 (Cell)
    ikupec@nsf.gov

    Virgo
    Fulvio Ricci
    Roma +39 06 49914261 (Office)
    Cascina +39 050 752 345 (Office)
    +39 348 3187354 (Cell)
    fulvio.ricci@roma1.infn.it

    GEO
    Susanne Milde
    Phone +49 331 583 93 55
    Mobile: +49 172 3931349
    milde@mildemarketing.de

    UK Science and Technology Facilities Council
    Terry O’Connor
    +44 1793 442006
    +44 77 68 00 61 84 (Cell)
    terry.o’connor@stfc.ac.uk

    Max Planck Institute for Gravitational Physics Hannover
    Benjamin Knispel
    Press Officer
    +49 511 762 19104
    benjamin.knispel@aei.mpg.de

    LIGO Opens New Window on the Universe with Observation of Gravitational Waves from Colliding Black Holes

    WASHINGTON, DC/Cascina, Italy

    For the first time, scientists have observed ripples in the fabric of spacetime called gravitational waves, arriving at the earth from a cataclysmic event in the distant universe. This confirms a major prediction of Albert Einstein’s 1915 general theory of relativity and opens an unprecedented new window onto the cosmos.

    Gravitational waves carry information about their dramatic origins and about the nature of gravity that cannot otherwise be obtained. Physicists have concluded that the detected gravitational waves were produced during the final fraction of a second of the merger of two black holes to produce a single, more massive spinning black hole. This collision of two black holes had been predicted but never observed.

    The gravitational waves were detected on September 14, 2015 at 5:51 a.m. Eastern Daylight Time (09:51 UTC) by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA. The LIGO Observatories are funded by the National Science Foundation (NSF), and were conceived, built, and are operated by Caltech and MIT. The discovery, accepted for publication in the journal Physical Review Letters, was made by the LIGO Scientific Collaboration (which includes the GEO Collaboration and the Australian Consortium for Interferometric Gravitational Astronomy) and the Virgo Collaboration using data from the two LIGO detectors.

    Based on the observed signals, LIGO scientists estimate that the black holes for this event were about 29 and 36 times the mass of the sun, and the event took place 1.3 billion years ago. About 3 times the mass of the sun was converted into gravitational waves in a fraction of a second—with a peak power output about 50 times that of the whole visible universe. By looking at the time of arrival of the signals—the detector in Livingston recorded the event 7 milliseconds before the detector in Hanford—scientists can say that the source was located in the Southern Hemisphere.

    According to general relativity, a pair of black holes orbiting around each other lose energy through the emission of gravitational waves, causing them to gradually approach each other over billions of years, and then much more quickly in the final minutes. During the final fraction of a second, the two black holes collide into each other at nearly one-half the speed of light and form a single more massive black hole, converting a portion of the combined black holes’ mass to energy, according to Einstein’s formula E=mc2. This energy is emitted as a final strong burst of gravitational waves. It is these gravitational waves that LIGO has observed.

    The existence of gravitational waves was first demonstrated in the 1970s and 80s by Joseph Taylor, Jr., and colleagues. Taylor and Russell Hulse discovered in 1974 a binary system composed of a pulsar in orbit around a neutron star. Taylor and Joel M. Weisberg in 1982 found that the orbit of the pulsar was slowly shrinking over time because of the release of energy in the form of gravitational waves. For discovering the pulsar and showing that it would make possible this particular gravitational wave measurement, Hulse and Taylor were awarded the Nobel Prize in Physics in 1993.

    The new LIGO discovery is the first observation of gravitational waves themselves, made by measuring the tiny disturbances the waves make to space and time as they pass through the earth.

    “Our observation of gravitational waves accomplishes an ambitious goal set out over 5 decades ago to directly detect this elusive phenomenon and better understand the universe, and, fittingly, fulfills Einstein’s legacy on the 100th anniversary of his general theory of relativity,” says Caltech’s David H. Reitze, executive director of the LIGO Laboratory.

    The discovery was made possible by the enhanced capabilities of Advanced LIGO, a major upgrade that increases the sensitivity of the instruments compared to the first generation LIGO detectors, enabling a large increase in the volume of the universe probed—and the discovery of gravitational waves during its first observation run. The US National Science Foundation leads in financial support for Advanced LIGO. Funding organizations in Germany (Max Planck Society), the U.K. (Science and Technology Facilities Council, STFC) and Australia (Australian Research Council) also have made significant commitments to the project. Several of the key technologies that made Advanced LIGO so much more sensitive have been developed and tested by the German UK GEO collaboration. Significant computer resources have been contributed by the AEI Hannover Atlas Cluster, the LIGO Laboratory, Syracuse University, and the University of Wisconsin- Milwaukee. Several universities designed, built, and tested key components for Advanced LIGO: The Australian National University, the University of Adelaide, the University of Florida, Stanford University, Columbia University of the City of New York, and Louisiana State University.

    “In 1992, when LIGO’s initial funding was approved, it represented the biggest investment the NSF had ever made,” says France Córdova, NSF director. “It was a big risk. But the National Science Foundation is the agency that takes these kinds of risks. We support fundamental science and engineering at a point in the road to discovery where that path is anything but clear. We fund trailblazers. It’s why the U.S. continues to be a global leader in advancing knowledge.”

    LIGO research is carried out by the LIGO Scientific Collaboration (LSC), a group of more than 1000 scientists from universities around the United States and in 14 other countries. More than 90 universities and research institutes in the LSC develop detector technology and analyze data; approximately 250 students are strong contributing members of the collaboration. The LSC detector network includes the LIGO interferometers and the GEO600 detector. The GEO team includes scientists at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute, AEI), Leibniz Universität Hannover, along with partners at the University of Glasgow, Cardiff University, the University of Birmingham, other universities in the United Kingdom, and the University of the Balearic Islands in Spain.

    “This detection is the beginning of a new era: The field of gravitational wave astronomy is now a reality,” says Gabriela González, LSC spokesperson and professor of physics and astronomy at Louisiana State University.

    LIGO was originally proposed as a means of detecting these gravitational waves in the 1980s by Rainer Weiss, professor of physics, emeritus, from MIT; Kip Thorne, Caltech’s Richard P. Feynman Professor of Theoretical Physics, emeritus; and Ronald Drever, professor of physics, emeritus, also from Caltech.

    “The description of this observation is beautifully described in the Einstein theory of general relativity formulated 100 years ago and comprises the first test of the theory in strong gravitation. It would have been wonderful to watch Einstein’s face had we been able to tell him,” says Weiss.

    “With this discovery, we humans are embarking on a marvelous new quest: the quest to explore the warped side of the universe—objects and phenomena that are made from warped spacetime. Colliding black holes and gravitational waves are our first beautiful examples,” says Thorne.

    Virgo research is carried out by the Virgo Collaboration, consisting of more than 250 physicists and engineers belonging to 19 different European research groups: 6 from Centre National de la Recherche Scientifique (CNRS) in France; 8 from the Istituto Nazionale di Fisica Nucleare (INFN) in Italy; 2 in The Netherlands with Nikhef; the Wigner RCP in Hungary; the POLGRAW group in Poland; and the European Gravitational Observatory (EGO), the laboratory hosting the Virgo detector near Pisa in Italy.

    Fulvio Ricci, Virgo Spokesperson, notes that, “This is a significant milestone for physics, but more importantly merely the start of many new and exciting astrophysical discoveries to come with LIGO and Virgo.”

    Bruce Allen, managing director of the Max Planck Institute for Gravitational Physics (Albert Einstein Institute), adds, “Einstein thought gravitational waves were too weak to detect, and didn’t believe in black holes. But I don’t think he’d have minded being wrong!”

    “The Advanced LIGO detectors are a tour de force of science and technology, made possible by a truly exceptional international team of technicians, engineers, and scientists,” says David Shoemaker of MIT, the project leader for Advanced LIGO. “We are very proud that we finished this NSF-funded project on time and on budget.”

    At each observatory, the two-and-a-half-mile (4-km) long L-shaped LIGO interferometer uses laser light split into two beams that travel back and forth down the arms (four-foot diameter tubes kept under a near-perfect vacuum). The beams are used to monitor the distance between mirrors precisely positioned at the ends of the arms. According to Einstein’s theory, the distance between the mirrors will change by an infinitesimal amount when a gravitational wave passes by the detector. A change in the lengths of the arms smaller than one-ten-thousandth the diameter of a proton (10-19 meter) can be detected.

    “To make this fantastic milestone possible took a global collaboration of scientists—laser and suspension technology developed for our GEO600 detector was used to help make Advanced LIGO the most sophisticated gravitational wave detector ever created,” says Sheila Rowan, professor of physics and astronomy at the University of Glasgow.

    Independent and widely separated observatories are necessary to determine the direction of the event causing the gravitational waves, and also to verify that the signals come from space and are not from some other local phenomenon.

    Toward this end, the LIGO Laboratory is working closely with scientists in India at the Inter-University Centre for Astronomy and Astrophysics, the Raja Ramanna Centre for Advanced Technology, and the Institute for Plasma to establish a third Advanced LIGO detector on the Indian subcontinent. Awaiting approval by the government of India, it could be operational early in the next decade. The additional detector will greatly improve the ability of the global detector network to localize gravitational-wave sources.

    “Hopefully this first observation will accelerate the construction of a global network of detectors to enable accurate source location in the era of multi-messenger astronomy,” says David McClelland, professor of physics and director of the Centre for Gravitational Physics at the Australian National University.

    Additional video and image assets can be found here: http://mediaassets.caltech.edu/gwave

    See the full article here .

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    LIGO
    LIGO Hanford Observatory

     
  • richardmitnick 4:06 pm on February 10, 2016 Permalink | Reply
    Tags: , , , , Earth's magnetosphere, Owens Valley Long Wavelength Array, ,   

    From Caltech: “Chasing Extrasolar Space Weather” 

    Caltech Logo
    Caltech

    02/10/2016
    Lori Dajose

    Earth’s magnetic field acts like a giant shield, protecting the planet from bursts of harmful charged solar particles that could strip away the atmosphere.

    Magnetosphere of Earth
    Earth’s magnetosphere

    Gregg Hallinan, an assistant professor of astronomy, aims to detect this kind of space weather on other stars to determine whether planets around these stars are also protected by their own magnetic fields and how that impacts planetary habitability.

    On Wednesday, February 10, at 8 p.m. in Beckman Auditorium, Hallinan will discuss his group’s efforts to detect intense radio emissions from stars and their effects on any nearby planets. Admission is free.

    What do you do?
    I am an astronomer. My primary focus is the study of the magnetic fields of stars, planets, and brown dwarfs—which are kind of an intermediate object between a planet and a star.

    Brown dwarf
    Brown dwarf

    Stars and their planets have intertwined relationships. Our sun, for example, produces coronal mass ejections, or CMEs, which are bubbles of hot plasma explosively ejected from the sun out into the solar system.

    Solar eruption 2012 by NASA's Solar Dynamic Observatory SDO
    CME

    Radiation and particles from these solar events bombard the earth and interact with the atmosphere, dominating the local “space weather” in the environment of Earth. Happily, our planet’s magnetic field shields and redirects CMEs toward the polar regions. This causes auroras—the colorful light in the sky commonly known as the Northern or Southern Lights.

    Auroras from around the world
    Auroras from around the world

    Our new telescope, the Owens Valley Long Wavelength Array, images the entire sky instantaneously and allows us to monitor extrasolar space weather on thousands of nearby stellar systems.

    Caltech Owens Valley Long Wavelength Array
    Caltech Owens Valley Long Wavelength Array

    When a star produces a CME, it also emits a bright burst of radio waves with a specific signature. If a planet has a magnetic field and it is hit by one of these CMEs, it will also become brighter in radio waves. Those radio signatures are very specific and allow you to measure very precisely the strength of the planet’s magnetic field. I am interested in detecting radio waves from exoplanets—planets outside of our solar system—in order to learn more about what governs whether or not a planet has a magnetic field.

    Why is this important?

    The presence of a magnetic field on a planet can tell us a lot. Like on our own planet, magnetic fields are an important line of defense against the solar wind, particularly explosive CMEs, which can strip a planet of its atmosphere. Mars is a good example of this. Because it didn’t have a magnetic field shielding it from the sun’s solar wind, it was stripped of its atmosphere long ago. So, determining whether a planet has a magnetic field is important in order to determine which planets could possibly have atmospheres and thus could possibly host life.

    How did you get into this line of work?

    From a young age, I was obsessed with astronomy—it’s all I cared for. My parents got me a telescope when I was 7 or 8, and from then on, that was it.

    As a grad student, I was looking at magnetic fields of cool—meaning low-temperature—objects. When I was looking at brown dwarfs, I found that they behave like planets in that they also have auroras. I had the idea that auroras could be the avenue to examine the magnetic fields of other planets. So brown dwarfs were my gateway into exoplanets.

    See the full article here .

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    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”
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  • richardmitnick 3:33 pm on February 10, 2016 Permalink | Reply
    Tags: , , , MIT Caltech Advanced aLIGO,   

    From Ethan Siegel via Forbes: “What Will It Mean If LIGO Detects Gravitational Waves?” 

    ForbesMag

    Forbes Magazine

    Starts with a bang
    Starts with a Bang

    Feb 9, 2016
    Ethan Siegel

    Cornell SXS teamTwo merging black holes simulation
    Image credit: Bohn et al 2015, SXS team, of two merging black holes and how they alter the appearance of the background spacetime in General Relativity.

    For over a decade, to very little fanfare, a new type of astronomy has been going on: gravitational wave astronomy. Rather than using a telescope to look out at the Universe, a gravitational wave detector uses lasers, fired and reflected perpendicular to one another, and then reconstructed to create a specific interference pattern when they’re reunited. This apparatus — the Laser Interferometer Gravitational-Wave Observatory (LIGO) — demonstrated its proof-of-concept from 2002-2010, and then was shut down for five years while it was upgraded.

    Caltech Ligo
    MIT/Caltech Advanced aLIGO

    In September of 2015, it was turned back on with the new upgrade (Advanced LIGO), and in just two days, the Advanced LIGO collaboration is going to make their first major announcement, and the speculation is this: that they’re going to announce the direct detection of the first gravitational wave. Here’s what that would mean.

    When [Albert] Einstein’s General Relativity was first proposed, it was incredibly different from the concept of space and time that came before. Rather than being fixed, unchanging quantities that matter and energy traveled through, they are dependent quantities: dependent on one another, dependent on the matter and energy within them, and changeable over time. If all you have is a single mass, stationary in spacetime (or moving without any acceleration), your spacetime doesn’t change. But if you add a second mass, those two masses will move relative to one another, will accelerate one another, and will change the structure of your spacetime. In particular, because you have a massive particle moving through a gravitational field, the properties of General Relativity mean that your mass will get accelerated, and will emit a new type of radiation: gravitational radiation.

    pulsar orbiting a binary companion and the gravitational waves (or ripples) in spacetime that ensue as a resul ESO
    Image credit: ESO/L. Calçada, of a pulsar orbiting a binary companion and the gravitational waves (or ripples) in spacetime that ensue as a result.

    This gravitational radiation is unlike any other type of radiation we know. Sure, it travels through space at the speed of light, but it itself is a ripple in the fabric of space. It carries energy away from the accelerating masses, meaning that if the two masses orbit one another, that orbit will decay over time. And it’s that gravitational radiation — the waves that cause ripples through space — that carries the energy away. For a system like the Earth orbiting the Sun, the masses are so (relatively) small and the distances so large that the system will take more than 10^150 years to decay, or many, many times the current age of the Universe. (And many times the lifetime of even the longest-lived stars that are theoretically possible!) But for black holes or neutron stars that orbit each other, those orbital decays have already been observed.

    Neutron stars merging
    Image credit: NASA (L), Max Planck Institute for Radio Astronomy / Michael Kramer, via http://www.mpg.de/7644757/W002_Physics-Astronomy_048-055.pdf.

    We suspect there are even stronger systems out there that we simply haven’t been able to detect, like black holes that spiral into and merge with one another. These should exhibit characteristic signals, like an inspiral phase, a merger phase, and then a ringdown phase, all of which result in the emission of gravitational waves that Advanced LIGO should be able to detect. The way the Advanced LIGO system works is nothing short of brilliant, and it takes advantage of the unique radiation of these gravitational waves. In particular, it takes advantage of how they cause spacetime to respond.

    These ripples work by compressing and then expanding space in directions that are perpendicular to one another, with frequencies and intensities that are dependent on a number of properties of where they come from, such as the two masses that spiral into one another, their distance from one another, and their distance from us. Advanced LIGO shoots two lasers of identical frequencies/wavelengths perpendicular to one another down a shaft four kilometers in either direction, bounces them off of mirrors many times over (effectively increasing the path-length to thousands of kilometers), and then brings them back together, where they create an interference pattern with one another.

    MIT Caltech Advanced aLIGO how it works schematic
    Image credit: public domain / US Government, of a schematic of how LIGO works. Modifications made by Krzysztof Zajączkowski.

    Under normal circumstances (where no gravitational waves pass through them), these path lengths are equal, and the interference pattern looks normal. But if a gravitational wave does pass through, that interference pattern will shift in a particular set of circumstances, and that shift will tell us the mass of each part of the system, how far apart they are and how distant they are from us.

    We have two Advanced LIGO system set up: one in the northwest United States (in Washington) and one in the southeast United States (in Louisiana), and if both detectors see the same thing, we’ll catch our first gravitational wave! This version of LIGO should be most sensitive to two black holes between 1 and a few hundred solar masses merging together out to many millions of light years: something that’s expected to happen at least a few times a year.

    Advanced aLIGO search range MIT Caltech
    Image credit: Caltech/MIT/LIGO Lab, of the Advanced LIGO search range.

    If the collaboration does announce their first detected event this Thursday, they’ll not only have this information for us, it will be a brand new successful test of Einstein’s General Relativity, and the first direct evidence for gravitational radiation ever. Advanced LIGO is the most advanced gravitational wave observatory ever constructed, and the first one that ought to actually see a true signal. With nearly 1,000 scientists on board, it’s the largest scientific collaboration designed to search for them as well. If all goes as suspected, a new era of astronomy is about to begin.

    MIT Caltech Advanced aLIGO Installing Upgrades
    Installing the Advanced LIGO upgrades. Image credit: Caltech/MIT/LIGO Lab, taken by Cheryl Vorvik.

    I’m very much against doing science by rumor. But if they find a gravitational wave, this is what it’ll teach us: that Einstein’s relativity is right, that gravitational radiation is real, and that merging black holes not only produce them, but that these waves can be detected. It’s a whole new type of astronomy — one that doesn’t use telescopes — and a whole new way to view black holes, neutron stars, and other objects that are otherwise mostly invisible. For the first time, we may be developing eyes for examining the Universe in a way that no living creature has ever examined it before.

    See the full article here .

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

     
  • richardmitnick 2:07 pm on February 10, 2016 Permalink | Reply
    Tags: , Biomolecules, , , ,   

    From DESY: “New method opens crystal clear views of biomolecules” 

    DESY
    DESY

    2016/02/11
    No writer credit found

    A scientific breakthrough gives researchers access to the blueprint of thousands of molecules of great relevance to medicine and biology. The novel technique, pioneered by a team led by DESY scientist Professor Henry Chapman from the Center for Free-Electron Laser Science CFEL and reported this week in the scientific journal Nature, opens up an easy way to determine the spatial structures of proteins and other molecules, many of which are practically inaccessible by existing methods. The structures of biomolecules reveal their modes of action and give insights into the workings of the machinery of life. Obtaining the molecular structure of particular proteins, for example, can provide the basis for the development of tailor-made drugs against many diseases. “Our discovery will allow us to directly view large protein complexes in atomic detail,” says Chapman, who is also a professor at the University of Hamburg and a member of the Hamburg Centre for Ultrafast Imaging CUI.

    Dimer crystals Detec of complex biomolecules like that of the photosystem II molecule shown here
    Slightly disordered crystals of complex biomolecules like that of the photosystem II molecule shown here produce a complex continous diffraction pattern (right, the disorder is greatly exaggerated) under X-ray light that contains far more information than the so-called Bragg peaks of a strongly ordered crystal alone (left). Credit: DESY, Eberhard Reimann

    To determine the spatial structure of a biomolecule, scientists mainly rely on a technique called crystallography. The new work offers a direct route to “read” the atomic structure of complex biomolecules by crystallography without the usual need for prior knowledge and chemical insight. “This discovery has the potential to become a true revolution for the crystallography of complex matter,” says the chairman of DESY’s board of directors, Professor Helmut Dosch.

    In crystallography, the structure of a crystal and of its constituents can be investigated by shining X-rays on it. The X-rays scatter from the crystal in many different directions, producing an intricate and characteristic pattern of numerous bright spots, called Bragg peaks (named after the British crystallography pioneers William Henry and William Lawrence Bragg). The positions and strengths of these spots contain information about the structure of the crystal and of its constituents. Using this approach, researchers have already determined the atomic structures of tens of thousands of proteins and other biomolecules.

    But the method suffers from two significant barriers, which make structure determination extremely difficult or sometimes impossible. The first is that the molecules must be formed into very high quality crystals. Most biomolecules do not naturally form crystals. However, without the necessary perfect, regular arrangement of the molecules in the crystal, only a limited number of Bragg peaks are visible. This means the structure cannot be determined, or at best only a fuzzy “low resolution” facsimile of the molecule can be found. This barrier is most severe for large protein complexes such as membrane proteins. These systems participate in a range of biological processes and many are the targets of today’s drugs. Great skill and quite some luck are needed to obtain high-quality crystals of them.

    Extreme Sudoku in three dimensions

    The second barrier is that the structure of a complex molecule is still extremely difficult to determine, even when good diffraction is available. “This task is like extreme Sudoku in three dimensions and a million boxes, but with only half the necessary clues,” explains Chapman. In crystallography, this puzzle is referred to as the phase problem. Without knowing the phase – the lag of the crests of one diffracted wave to another – it is not possible to compute an image of the molecule from the measured diffraction pattern. But phases can’t be measured. To solve the tricky phase puzzle, more information must be known than just the measured Bragg peaks. This additional information can sometimes be obtained by X-raying crystals of chemically modified molecules, or by already knowing the structure of a closely-related molecule.

    When thinking about why protein crystals do not always “diffract”, Chapman realised that imperfect crystals and the phase problem are linked. The key lies in a weak “continuous” scattering that arises when crystals become disordered. Usually, this non-Bragg, continuous diffraction is thought of as a nuisance, although it can be useful for providing insights into vibrations and dynamics of molecules. But when the disorder consists only of displacements of the individual molecules from their ideal positions in the crystal then the “background” takes on a much more complex character – and its rich structure is anything but diffuse. It then offers a much bigger prize than the analysis of the Bragg peaks: the continuously-modulated “background” fully encodes the diffracted waves from individual “single” molecules.

    “If you would shoot X-rays on a single molecule, it would produce a continuous diffraction pattern free of any Bragg spots,” explains lead author Dr. Kartik Ayyer from Chapman’s CFEL group at DESY. “The pattern would be extremely weak, however, and very difficult to measure. But the ‘background’ in our crystal analysis is like accumulating many shots from individually-aligned single molecules. We essentially just use the crystal as a way to get a lot of single molecules, aligned in common orientations, into the beam.” With imperfect, disordered crystals, the continuous diffraction fills in the gaps and beyond the Bragg peaks, giving vastly more information than in normal crystallography. With this additional gain in information, the phase problem can be uniquely solved without having to resort to other measurements or assumptions. In the analogy of the Sudoku puzzle, the measurements provide enough clues to always arrive at the right answer.

    The best crystals are imperfect crystals

    This novel concept leads to a paradigm shift in crystallography — the most ordered crystals are no longer the best to analyse with the novel method. Instead, the best crystals are imperfect crystals. “For the first time we have access to single molecule diffraction – we have never had this in crystallography before,” he explains. “But we have long known how to solve single-molecule diffraction if we could measure it.” The field of coherent diffractive imaging, spurred by the availability of laser-like beams from X-ray free-electron lasers, has developed powerful algorithms to directly solve the phase problem in this case, without having to know anything at all about the molecule. “You don’t even have to know chemistry,” says Chapman, “but you can learn it by looking at the three-dimensional image you get.”

    To demonstrate their novel analysis method, the Chapman group teamed up with the group of Professor Petra Fromme from the Arizona State University (ASU), and other colleagues from ASU, University of Wisconsin, the Greek Foundation for Research and Technology – Hellas FORTH, and SLAC National Accelerator Laboratory in the U.S. They used the world’s most powerful X-ray laser LCLS at SLAC to X-ray imperfect microcrystals of a membrane protein complex called Photosystem II that is part of the photosynthesis machinery in plants.

    SLAC LCLS Inside
    Inside LCLS

    Including the continuous diffraction pattern into the analysis immediately improved the spatial resolution around a quarter from 4.5 Ångström to 3.5 Ångström (an Ångström is 0.1 nanometres). The obtained image gave fine definition of molecular features that usually require fitting a chemical model to see. “That is a pretty big deal for biomolecules,” explains co-author Dr. Anton Barty from DESY. “And we can further improve the resolution if we take more patterns.” The team had only a few hours of measuring time for these experiments, while full-scale measuring campaigns usually last a couple of days.

    The scientists hope to obtain even clearer and higher resolution images of photosystem II and many other macromolecules with their new technique. “This kind of continuous diffraction has actually been seen for a long time from many different poorly-diffracting crystals,” says Chapman. “It wasn’t understood that you can get structural information from it and so analysis techniques suppressed it. We’re going to be busy to see if we can solve structures of molecules from old discarded data.”

    Reference:
    Macromolecular diffractive imaging using imperfect crystals; Kartik Ayyer et al.; Nature (2016); DOI: 10.1038/nature16949

    See the full article here .

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    desi

    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 1:34 pm on February 10, 2016 Permalink | Reply
    Tags: , , , Kilonovas   

    From AAS NOVA: “Can JWST Follow Up on Gravitational-Wave Detections?” 

    AASNOVA

    American Astronomical Society

    10 February 2016
    Susanna Kohler

    Kilanova
    Kilonova. Popular Mechanics

    Bitten by the gravitational-wave bug? While we await Thursday’s press conference, here’s some food for thought: if LIGO were able to detect gravitational waves from compact-object mergers, how could we follow up on the detections?

    Caltech Ligo
    MIT/Caltech Advanced aLIGO

    A new study investigates whether the upcoming James Webb Space Telescope (JWST) will be able to observe electromagnetic signatures of some compact-object mergers.

    NASA Webb telescope annotated
    NASA/ESA/CSA Webb

    Hunting for Mergers

    Studying compact-object mergers (mergers of black holes and neutron stars) can help us understand a wealth of subjects, like high-energy physics, how matter behaves at nuclear densities, how stars evolve, and how heavy elements in the universe were created.

    The Laser Interferometer Gravitational-Wave Observatory (LIGO) is searching for the signature ripples in spacetime identifying these mergers, but gravitational waves are squirrelly: LIGO will only be able to localize wave sources to tens of square degrees. If we want to find out more about any mergers LIGO discovers in gravitational waves, we’ll need a follow-up search for electromagnetic counterparts with other observatories.

    The Kilonova Key

    One possible electromagnetic counterpart is kilonovae, explosions that can be produced during a merger of a binary neutron star or a neutron star–black hole system. If the neutron star is disrupted during the merger, some of the hot mass is flung outward and shines brightly by radioactive decay.

    Kilonovae are especially promising as electromagnetic counterparts to gravitational waves for three reasons:

    1.They emit isotropically, so the number of observable mergers isn’t limited by relativistic beaming.
    2.They shine for a week, giving follow-up observatories time to search for them.
    3.The source location can be easily recovered.

    The only problem? We don’t currently have any sensitive survey instruments in the near-infrared band (where kilonova emission peaks) that can provide coverage over tens of square degrees. Luckily, we will soon have just the thing: JWST, launching in 2018!

    JWST’s Search

    n a recent study, a team of authors led by Imre Bartos (Columbia University) evaluate whether JWST will be capable of catching these kilonovae if LIGO finds gravitational wave signals.

    Bartos and collaborators calculate that, given the sensitivity of the different filters on JWST’s Near-Infrared Camera [NIRCAM], the instrument should easily be able to detect a kilonova 200 Mpc away (a typical distance at which LIGO might be able to find a neutron-star binary).

    NASA Webb NIRcam
    JWST NIRCAM

    But there’s a catch: 10 deg^2 is a really big sky area, and it would take JWST an unfeasible amount of time (days!) to fully cover it.

    The authors suggest instead using a targeted search. Since most mergers are expected to be in or near galaxies, JWST could specifically focus the follow-up search on known galaxies within the search area. This approach would bring the total search time down to 12.6 hours, which is within the realm of feasibility. And this time could be reduced even further by concentrating on galaxies most likely to host kilonovae, like those with high star-formation rates.

    The conclusion: if LIGO is able to detect gravitational waves, JWST will provide an excellent means to follow up on the detection in the attempt to identify the source.
    Citation

    I. Bartos et al 2016 ApJ 816 61. doi:10.3847/0004-637X/816/2/61

    See the full article here .

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  • richardmitnick 12:52 pm on February 10, 2016 Permalink | Reply
    Tags: , , , Reflection nebula   

    From ESO: “A Star’s Moment in the Spotlight” 

    ESO 50 Large

    European Southern Observatory

    10 February 2016
    Richard Hook
    ESO Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    ESO Reflection nebula IC2631

    A newly formed star lights up the surrounding cosmic clouds in this new image from ESO’s La Silla Observatory in Chile. Dust particles in the vast clouds that surround the star HD 97300 diffuse its light, like a car headlight in enveloping fog, and create the reflection nebula IC 2631. Although HD 97300 is in the spotlight for now, the very dust that makes it so hard to miss heralds the birth of additional, potentially scene-stealing, future stars.

    The glowing region in this new image from the MPG/ESO 2.2-metre telescope is a reflection nebula known as IC 2631.

    ESO 2.2 meter telescope with dome open
    MPG/ESO 2.2-metre telescope with dome open.

    These objects are clouds of cosmic dust that reflect light from a nearby star into space, creating a stunning light show like the one captured here. IC 2631 is the brightest nebula in the Chamaeleon Complex, a large region of gas and dust clouds that harbours numerous newborn and still-forming stars. The complex lies about 500 light-years away in the southern constellation of Chamaeleon.

    IC 2631 is illuminated by the star HD 97300, one of the youngest — as well as most massive and brightest — stars in its neighbourhood. This region is full of star-making material, which is made evident by the presence of dark nebulae noticeable above and below IC 2631 in this picture. Dark nebulae are so dense with gas and dust that they prevent the passage of background starlight.

    Despite its dominating presence, the heft of HD 97300 should be kept in perspective. It is a T Tauri star, the youngest visible stage for relatively small stars. As these stars mature and reach adulthood they will lose mass and shrink. But during the T Tauri phase these stars have not yet contracted to the more modest size that they will maintain for billions of years as main sequence stars.

    These fledging stars already have surface temperatures similar to their main sequence phase and accordingly, because T Tauri-phase objects are essentially jumbo versions of their later selves, they look brighter in their oversized youth than in maturity. They have not yet started to fuse hydrogen into helium in their cores, like normal main sequence stars, but are just starting to flex their thermal muscles by generating heat from contraction.

    Reflection nebula, like the one spawned by HD 97300, merely scatter starlight back out into space. Starlight that is more energetic, such as the ultraviolet radiation pouring forth from very hot new stars, can ionise nearby gas, making it emit light of its own. These emission nebulae indicate the presence of hotter and more powerful stars, which in their maturity can be observed across thousands of light-years. HD 97300 is not so powerful, and its moment in the spotlight is destined not to last.

    See the full article here .

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

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  • richardmitnick 2:50 am on February 10, 2016 Permalink | Reply
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    From perth now for CSIRO: “Australian astronomers zero-in on the ‘Great Attractor’ pulling on our Milky Way” 

    perth now

    perth now

    CSIRO bloc

    Commonwealth Scientific and Industrial Research Organisation

    February 9, 2016
    Jamie Seidel

    A STRANGE intergalactic force is drawing our Milky Way galaxy inward. We don’t know what, or why. But a hidden swarm of hundreds of nearby galaxies just discovered by Australian astronomers may help reveal the identity of the ‘Great Attractor’.

    Great Attractor galaxies

    This pack of galaxies has been spotted by International Centre for Radio Astronomy Research (ICRAR) researchers using CSIRO’s Parkes Observatory in NSW.

    CSIRO Parkes Observatory

    The study was published today in Astronomical Journal.

    Despite being ‘just next door’ in astronomical terms — a mere 250 million light years away — these galaxies have remained hidden from view because they are on the opposite side of our own.

    The intensity of stars and dust crowded together along the plane of the Milky Way is directly in the line of sight — masking everything behind it from view.

    That something must be there has been known for some time.

    Its immense gravitational pull — the equivalent of a million billion Suns — has been observed through calculations of strange deviations in the flight path of nearby galaxies.

    And our own.

    In the absence of any indication as to what it may be, astronomers have simply dubbed it the Great Attractor.

    Universe map
    Panoramic view of the entire near-infrared sky. The location of the Great Attractor is shown following the long blue arrow at bottom-right.

    Our Milky Way is just one of hundreds of thousands of local galaxies ensnared by its grasp.

    And we’re hurtling towards the mysterious source of this attraction force at more than two million kilometres per hour.

    GREAT ATTRACTOR

    “We don’t actually understand what’s causing this gravitational acceleration on the Milky Way or where it’s coming from,” says study lead author Professor Lister Staveley-Smith of the University of Western Australia.

    “We know that in this region there are a few very large collections of galaxies we call clusters or superclusters, and our whole Milky Way is moving towards them.”

    Superclusters
    Superclusters

    Essentially, all we know is that there is an immense — but probably diffuse — concentration of mass lurking some 250 million light years away.

    Is it a monster-black hole? Or a whole army of these collapsed points in space-time?

    “Some astronomers think the Great Attractor is a super-supercluster of galaxies; some astronomers think that some regions of the universe are “darker” than others,” Professor Staveley-Smith says, referring to densities of the invisible source of gravity dubbed Dark Matter.

    “Some physicists are even considering the possibility that the mass fluctuations in the universe are so significant that astronomers may be fundamentally misinterpreting the relationship between gravity and motion.”

    It all remains speculation.

    But observing and understanding the distribution and behaviour of the new galaxies may uncover vital clues.

    “The ‘Great Attractor’ lies at the intersection of several large-scale filaments of galaxies,” says Dr Barbel Koribalski of CSIRO Astronomy and Space Science. “One could picture a giant hoover with galaxies near and far slowly streaming towards it. We can’t see much of this hoover, but we can measure the motion of the galaxies.”

    What is doing the hoovering is the issue.

    SUPER SIGHT

    The Parkes radio telescope is a 64-metre dish that was activated in 1961. It was more recently modified with an innovative receiver, allowing the international team of scientists to peer past the ‘interference’ of our galactic core into unexplored space.

    “The Milky Way is very beautiful of course and it’s very interesting to study our own galaxy but it completely blocks out the view of the more distant galaxies behind it,” says Professor Staveley-Smith.

    Not so completely anymore.

    What the survey revealed was a field of 883 galaxies, a third of which had not previously been suspected says Professor Staveley-Smith.

    University of Cape Town astronomer Professor Renée Kraan-Korteweg — also part of the research team — said astronomers have been trying to map the galaxies hidden behind the Milky Way for decades.

    “We’ve used a range of techniques but only radio observations have really succeeded in allowing us to see through the thickest foreground layer of dust and stars,” she said.

    “An average galaxy contains 100 billion stars, so finding hundreds of new galaxies hidden behind the Milky Way points to a lot of mass we didn’t know about until now.”

    So what caused this odd accumulation of galaxies?

    That bit remains the problem.

    BIONIC EYE

    Dr Koribalski says innovative technologies on the Parkes radio telescope had made it possible to survey large areas of the sky quickly. And things are about to get much, much better.

    “Detecting galaxies behind the Milky Way (in the so-called Zone of Avoidance) and measuring their motions is important to pinpoint its location and total mass,” she says. “The Parkes multibeam system made this possible. With this receiver we’re able to map the sky 13 times faster than we could before and make new discoveries at a much greater rate.”

    Copies of this receiver have been purchased from CSIRO by United States and Chinese astronomers to upgrade their own radio telescopes.

    But this receiver is being temporarily removed from the Parkes telescope this week. A new Phased-Array Feed (PAF) is being attached for testing.

    Parkes Phased Array Feed

    “The PAF is a huge technological advance, a breakthrough of major proportion that will be able to do fast and sensitivities surveys of the sky, (and is) bound to make many new discoveries,” Dr Koribalski says. “How to learn more about the Great Attractor? The answer is WALLABY — the upcoming Australian SKA Pathfinder (ASKAP) HI All Sky Survey – which is expected to spot more than 500,000 galaxies.”

    SKA ASKAP telescope
    ASKAP

    This will offer much faster scanning of the skies than current equipment, combined with a twenty-fold increase in resolution.

    Dr Koribalski says she expects the new scope will detect an additional 10,000 galaxies tucked away behind our own.

    It may also, hopefully, paint a trail to the ‘Great Attractor’ itself.

    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 2:02 am on February 10, 2016 Permalink | Reply
    Tags: , ,   

    From Symmetry: “Neutrinos on a seesaw” 

    Symmetry

    02/09/16
    Matthew R. Francis

    Neutrino See-Saw Model for Neutrino Masses

    Mass is a fundamental property of matter, but there’s still a lot about it we don’t understand—especially when it comes to the strangely tiny masses of neutrinos.

    An idea called the seesaw mechanism proposes a way to explain the masses of these curious particles. If shown to be correct, it could help us understand a great deal about the nature of fundamental forces and—maybe—why there’s more matter than antimatter in the universe today.

    Wibbly-wobbly massy-wassy stuff

    The masses of the smallest bits of matter cover a wide range. Electrons are roughly 1800 times less massive than protons and neutrons, which are one hundred times less massive than the Higgs boson. Other rare beasts like the top quark are heavier still.

    Then we have the neutrinos, which don’t fit in at all.

    According to the Standard Model of particles and forces that emerged in the 1970s, neutrinos were massless. Experiments seemed to concur. However, over the next two decades, physicists showed that neutrinos change their flavor, or type.

    Neutrinos come in three varieties: electron, muon and tau. Think of them as Neapolitan ice cream: The strawberry is the electron neutrino; the vanilla is the muon neutrino; and the chocolate is the tau neutrino.

    By the late 1980s, physicists were reasonably good at scooping out the strawberry; most experiments were designed to detect electron neutrinos only. But they were seeing far fewer than theory predicted they should.

    By 1998, researchers discovered the missing neutrinos could be explained by oscillation—the particles were changing from one flavor to another. By figuring out how to detect the other flavors, they showed they could account for the remainder of the missing neutrinos.

    This discovery forced them to reconsider the mass of the neutrino, since neutrinos can oscillate only if they have a tiny—but nonzero—mass.

    Today, “just from experimental facts, we know that neutrino masses are way smaller compared to all the other elementary [matter particle] masses,” says Mu-Chun Chen, a theoretical physicist at the University of California, Irvine.

    We don’t yet know exactly how much mass they have, but astronomical observations show they’re likely around a millionth of the mass of an electron—or even less. And this small mass could be a product of the seesaw mechanism.

    I am not left-handed!

    To visualize another important property of neutrinos, make a “thumbs-up” gesture with your left hand. Your fingers will curl the way the neutrino rotates, and your thumb will point in the direction it travels. This combination makes for a “left-handed” particle. Antineutrinos, the antimatter version of neutrinos, are right-handed: Take your right hand and make a thumbs-up to show the relation between their spin and motion.

    Some particles such as electrons or quarks don’t spin in any particular direction relative to the way they move; they are neither purely right- nor left-handed. So far, scientists have only ever observed left-handed neutrinos.

    But the seesaw mechanism predicts that there are two kinds of neutrinos: the light, left-handed ones we know and—on the other end of the metaphorical seesaw—heavy, right-handed neutrinos that we’ve never seen. The seesaw itself is a ratio: the higher the mass of the right-handed neutrino, the lower the mass of the left-handed neutrinos. Based on experiments, these right-handed neutrinos would be extraordinarily massive, perhaps 10^15 (one quadrillion) times heavier than a proton.

    And there’s more: The seesaw mechanism predicts that if right-handed neutrinos exist, then they would be their own antiparticles. This could give us a clue to how our universe came to be full of matter.

    One idea is that in the first fraction of a second after the big bang, the universe produced just a tiny bit more matter than antimatter. After most particles annihilated with their antimatter counterparts, that imbalance left us with the matter we have today. Most of the laws of physics don’t distinguish between matter and antimatter, so something beyond the Standard Model must explain the asymmetry.

    Particles that are their own antiparticles can produce situations that violate some of the normal rules of physics. If right-handed neutrinos—which are their own antineutrinos—exist, then neutrinos could present the same kind of symmetry violation that might have happened for other types of matter. Exactly how that carries over to matter other than neutrinos, though, is still an area of active research for Chen and other physicists.

    Searching for the seesaw

    Scientists think they have yet to see these heavy right-handers for two reasons. First, the only force they know to act on neutrinos is the weak force, and the weak force acts only on left-handed particles. Right-handed neutrinos might not interact with any of the known forces.

    Second, right-handed neutrinos would be too massive to be stable in our universe, and they would require too much energy to be created in even the most powerful particle accelerator. However, these particles could leave footprints in other experiments.

    Today, scientists are studying the light, left-handed neutrinos that we can see to look for signs that could give us a verdict on the seesaw mechanism.

    For one, they’re looking to see if neutrinos are their own antiparticles. That wouldn’t necessarily mean that the seesaw mechanism is true, but finding it would be a big point in the seesaw mechanism’s favor.

    The seesaw mechanism goes hand-in-hand with grand unified theories—theories that unite the strong, weak and electromagnetic theory into a single force at high energies. If scientists find evidence of the seesaw mechanism, they could learn important things about how the forces are related.

    The seesaw mechanism is the most likely way to explain how neutrinos got their mass. However, frustratingly, the nature of the explanation pushes many of its testable consequences out of experimental reach.

    The best hope lies in persistent experimentation, and—as with the discovery of neutrino oscillation in the first place—hunting for anything that doesn’t quite fit expectations.

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 1:43 pm on February 9, 2016 Permalink | Reply  

    From phys.org: “Superconductors could detect superlight dark matter” 

    physdotorg
    phys.org

    February 9, 2016
    Lisa Zyga

    Abell 1689
    A massive cluster of yellowish galaxies, seemingly caught in a red and blue spider web of eerily distorted background galaxies, makes for a spellbinding picture from the new Advanced Camera for Surveys [ACS] aboard NASA’s Hubble Space Telescope. To make this unprecedented image of the cosmos, Hubble peered straight through the center of one of the most massive galaxy clusters known, called Abell 1689. The gravity of the cluster’s trillion stars — plus dark matter — acts as a 2-million-light-year-wide lens in space. This gravitational lens bends and magnifies the light of the galaxies located far behind it. Some of the faintest objects in the picture are probably over 13 billion light-years away (redshift value 6). Strong gravitational lensing as observed by the Hubble Space Telescope in Abell 1689 indicates the presence of dark matter. Credit: NASA, N. Benitez (JHU), T. Broadhurst (Racah Institute of Physics/The Hebrew University), H. Ford (JHU), M. Clampin (STScI),G. Hartig (STScI), G. Illingworth (UCO/Lick Observatory), the ACS Science Team and ESA

    NASA Hubble ACS
    ACS

    NASA Hubble Telescope
    NASA/ESA HUbble

    Many experiments are currently searching for dark matter—the invisible substance that scientists know exists only from its gravitational effect on stars, galaxies, and other objects made of ordinary matter. On Earth, scientists are using particle accelerators such as the Large Hadron Collider (LHC) to search for dark matter, while keeping an eye out elsewhere with detectors in space and even detectors located thousands of feet underground.

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

    Although scientists have covered all of their bases location-wise, these detectors may not be sensitive enough to detect dark matter if the mass of the dark matter is less than about 10 GeV (10 billion electron volts).

    To address this problem, physicists are working on developing ever more sensitive dark matter detectors. In a new paper, researchers have proposed a new type of dark matter detector made of superconductors—materials that conduct electricity with zero resistance at ultracold temperatures—that may offer the highest sensitivity yet for detecting “superlight” dark matter.

    Superconductivity
    Superconductivity

    Superlight dark matter has a mass at the low end of the range of 1 keV (1000 electron volts) to 10 GeV, or in other words, up to a million times lighter than the proton.

    The physicists, Yonit Hochberg and Kathryn M. Zurek at Lawrence Berkeley National Laboratory and the University of California, Berkeley, and Yue Zhao at Stanford University (now at the University of Michigan), have published a paper on the superconducting detectors in a recent issue of Physical Review Letters.

    “The greatest significance of our work is the potential ability to detect dark matter with mass between a thousand to a million times lighter than the mass of the proton,” Zurek told Phys.org. “Current dark matter direct detection experiments and other proposed methods are not sensitive to such light dark matter. Superconducting detectors are the only (proposed) game in town for dark matter in this mass range.”

    Although most of the time dark matter does not interact with anything, scientists have to assume it interacts with ordinary matter somehow, or else they could not detect it in the lab. But it’s unclear whether dark matter interacts with electrons, nuclei, both, or something else.

    In general, dark matter detectors are based on the principle that, if a dark matter particle were to hit the detector and interact with it, the collision would produce another type of particle such as a photon or phonon (a quanta of vibration) at a specific energy. The detector material is extremely important, as the interaction between dark matter and the detector determines the specific properties of the particle that is produced. Some of the most highly sensitive detectors today are made of liquid xenon (LZ detector), germanium crystal (SuperCDMS), and other similar materials.

    In the new paper, the physicists showed that a dark matter detector made out of a superconducting material, such as ultrapure aluminum, could be the most sensitive material yet, capable of detecting dark matter with a mass of a few hundred keV or less. The sensitivity arises from the fact that superconductors have a zero or near-zero band gap, which is the energy gap that electrons must cross to allow a material to conduct electricity. Aluminum, for example, has a tiny band gap of 0.3 meV (0.0003 eV).

    “Superconducting detectors are more sensitive than other detectors due to their tiny energy gap,” Hochberg said. “This tiny gap means that they are sensitive to very small energy depositions, which in turn means that they are sensitive to very light dark matter masses, down to a million times lighter than the proton. This is in contrast to, for example, standard semiconductors, which (due to their thousand-times-larger band gap) can be sensitive to dark matter only down to a thousand times lighter than the proton.”

    The idea is that one of the dark matter particles that are thought to be constantly flowing through the Earth will scatter off a free electron in the superconductor. In a superconductor, the free electrons are bound into Cooper pairs with a binding energy of a little less than 1 meV. If a dark matter particle has enough energy to pull an electron above the material’s band gap, it will break the Cooper pair. In this way, the superconductor absorbs the energy of the incoming dark matter particle. Then a second device (a calorimeter) measures the heat energy deposited in the absorber, providing direct evidence of the dark matter particle.

    The physicists predict that reasonable improvements in current detector technology could make this concept feasible in the near future. One of the biggest challenges (as in all dark matter detectors) will be to reduce the noise from non-dark-matter sources, such as thermal and environmental noise. If the superconductor detector can be built, it would provide the most sensitive test of dark matter to date and give scientists a better chance of finding out what the majority of matter in the universe is made of.

    More information: Yonit Hochberg, Yue Zhao, and Kathryn M. Zurek. “Superconducting Detectors for Superlight Dark Matter.” Physical Review Letters. DOI: 10.1103/PhysRevLett.116.011301 , Also at arXiv:1504.07237 [hep-ph]

    See the full article here .

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 12:43 pm on February 9, 2016 Permalink | Reply
    Tags: , , , NGC 253, Suprime-Cam instrument   

    From Subaru: “Galactic Space Oddity Discovered 

    NAOJ

    NAOJ

    February 8, 2016
    No writer credit found

    An international team of researchers led by Aaron Romanowsky of San José State University has used the Subaru Telescope to identify a faint dwarf galaxy disrupting around a nearby giant spiral galaxy. The observations provide a valuable glimpse of a process that is fleeting but important in shaping galaxies.

    “The outer regions of giant galaxies like our own Milky Way appear to be a jumble of debris from hundreds of smaller galaxies that fell in over time and splashed into smithereens,” said Romanowsky. “These dwarfs are considered building blocks of the giants, but the evidence for giants absorbing dwarfs has been largely circumstantial. Now we have caught a pair of galaxies in the act of a deadly embrace.”

    NGC 253-dw2 dwarf galaxy disturbing
    Close-up view of the dwarf galaxy NGC 253-dw2. The closely packed red dots show that it is composed of individual stars.

    The two objects in the study are NGC 253 [Sculpture] , also called the Silver Dollar galaxy, and the newly discovered dwarf NGC 253-dw2.

    NGC 253 Sculpture or Silver Dollar Galaxy
    NGC 253 Sculpture Galaxy

    They are located in the Southern constellation of Sculptor at a distance of 11 million light years from Earth, and are separated from each other by about 160 thousand light years. The dwarf has an elongated appearance that is the hallmark of being stretched apart by the gravity of a larger galaxy.

    “The dwarf has been trapped by its giant host and will not survive intact for much longer,” said team member Nicolas Martin, of the Strasbourg Observatory. “The next time it plunges closer to its host, it could be shredded into oblivion. However, the host may suffer some damage too, if the dwarf is heavy enough.”

    The interplay between the two galaxies may resolve an outstanding mystery about NGC 253, as the giant spiral shows signs of being disturbed by a dwarf. The disturber was previously unseen and presumed to have perished, but now the likely culprit has been found. “This looks like a case of galactic stealth attack,” said Gustavo Morales of Heidelberg University. “The dwarf galaxy has dived in from the depths of space and barraged the giant, while remaining undetected by virtue of its extreme faintness.”

    The discovery of NGC 253-dw2 has an unusual pedigree. It began with a digital image of the giant galaxy taken by astrophotographer Michael Sidonio using a 30 centimeter (12 inch) diameter amateur telescope in Australia. Other members of the international team noticed a faint smudge in the image and followed it up with a larger, 80 centimeter (30 inch) amateur telescope in Chile, led by Johannes Schedler. The identity of the object was still not clear, and it was observed with the 8 meter (27 foot) Subaru Telescope on the summit of Mauna Kea in Hawaii, in December 2014. “In the first image, we weren’t sure if there was really a faint galaxy or if it was some kind of stray reflection,” said David Martínez-Delgado, also from Heidelberg University. “With the high-quality imaging of the Suprime-Cam instrument on the Subaru Telescope, we can now see that the smudge is composed of individual stars and is a bona fide dwarf galaxy. This discovery is a wonderful example of fruitful collaboration between amateur and professional astronomers.”

    NAOJ Subaru Hyper Suprime Camera
    NAOJ Subaru Hyper Suprime Camera

    This discovery is a wonderful example of fruitful collaboration between amateur and professional astronomers.”

    The findings are in research paper published in the Monthly Notices of the Royal Astronomical Society Letters by Oxford University Press, as “Satellite accretion in action: a tidally disrupting dwarf spheroidal around the nearby spiral galaxy NGC 253” by Romanowsky et al., first online on January 23, 2016 (http://mnrasl.oxfordjournals.org/lookup/doi/10.1093/mnrasl/slv207).

    The research team:

    Aaron J. Romanowsky (San José State University and University of California Observatories, USA)
    David Martínez-Delgado (Zentrum für Astronomie der Universität Heidelberg, Germany)
    Nicolas F. Martin (Université de Strasbourg, France and Max-Planck-Institut für Astronomie, Germany)
    Gustavo Morales (Zentrum für Astronomie der Universität Heidelberg, Germany)
    Zachary G. Jennings (University of California, USA)
    R. Jay GaBany (Black Bird Observatory II, USA)
    Jean P. Brodie (University of California Observatories and University of California, USA)
    Eva K. Grebel (Zentrum für Astronomie der Universität Heidelberg, Germany)
    Johannes Schedler (Cerro Tololo Inter-American Observatory, Chile)
    Michael Sidonio (Terroux Observatory, Australia)

    Links:

    http://subarutelescope.org/Pressrelease/2014/07/01/index.html
    http://subarutelescope.org/Pressrelease/2012/02/08/index.htmll

    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.

    NAOJ Subaru Telescope

    NAOJ Subaru Telescope interior
    Subaru

    ALMA Array
    ALMA

    sft
    Solar Flare Telescope

    Nobeyama Radio Telescope - Copy
    Nobeyama Radio Observatory

    Nobeyama Solar Radio Telescope Array
    Nobeyama Radio Observatory: Solar

    Misuzawa Station Japan
    Mizusawa VERA Observatory

    NAOJ Okayama Astrophysical Observatory Telescope
    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.

     
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