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  • richardmitnick 10:55 am on April 29, 2016 Permalink | Reply
    Tags: , , , NRAO,   

    From NRAO: “Gravitational Wave Search Provides Insights into Galaxy Evolution and Mergers” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    5 April 2016
    Elizabeth Ferrara
    NANOGrav press officer
    elizabeth.ferrara@nanograv.org
    301-286-7057

    Charles Blue
    NRAO Public Information Officer
    cblue@nrao.edu
    (434) 296-0314

    1
    The Earth is constantly jostled by low-frequency gravitational waves from supermassive black hole binaries in distant galaxies. Astrophysicists are using pulsars as a galaxy-sized detector to measure the Earth’s motion from these waves. Credit: B. Saxton (NRAO/AUI/NSF)

    Summary: New results from NANOGrav – the North American Nanohertz Observatory for Gravitational Waves – establish astrophysically significant limits in the search for low-frequency gravitational waves. This result provides insight into how often galaxies merge and how those merging galaxies evolve over time. To obtain this result, scientists required an exquisitely precise, nine-year pulsar-monitoring campaign conducted by two of the most sensitive radio telescopes on Earth, the Green Bank Telescope in West Virginia and the Arecibo Observatory in Puerto Rico.

    NRAO/GBT
    NRAO/GBT, West Virginia, USA

    NAIC/Arecibo Observatory
    NAIC/Arecibo Observatory, Puerto Rico, USA

    The recent LIGO detection of gravitational waves from merging black holes with tens of solar masses has confirmed that distortions in the fabric of space-time can be observed and measured [1].

    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib
    Credit: MPI for Gravitational Physics/W.Benger-Zib

    Caltech/MIT Advanced aLIGO Hanford Washington USA installation
    Caltech/MIT Advanced aLIGO Hanford Washington USA installation

    Researchers from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) have spent the past decade searching for low-frequency gravitational waves emitted by black hole binaries with masses many millions of times larger than those seen by LIGO.

    Analysis of NANOGrav’s nine-year dataset provides very constraining limits on the prevalence of such supermassive black hole binaries throughout the Universe. Given scientists’ current understanding of how often galaxies merge, these limits point to fewer detectable supermassive black hole binaries than were previously expected. This result has significant impacts on our understanding of how galaxies and their central black holes co-evolve.

    Low-frequency gravitational waves are very difficult to detect, with wavelengths spanning light-years and originating from black hole binaries in galaxies spread across the sky. The combination of all these giant binary black holes leads to a constant “hum” of gravitational waves that models predict should be detectable at Earth. Astrophysicists call this effect the “stochastic gravitational wave background,” and detecting it requires special analysis techniques.

    Pulsars are the cores of massive stars left behind after stars go supernova. The fastest pulsars rotate hundreds of times each second and emit a pulse of radio waves every few milliseconds. These millisecond pulsars (MSPs) are considered nature’s most precise clocks and are ideal for detecting the small signal from gravitational waves. “This measurement is possible because the gravitational wave background imprints a unique signature onto the radio waves seen from a collection of MSPs,” said Justin Ellis, Einstein Fellow at NASA’s Jet Propulsion Laboratory, California Institute of Technology in Pasadena, California, and a co-author on the report published in Astrophysical Journal.

    Astrophysicists use computer models to predict how often galaxies merge and form supermassive black hole binaries. Those models use several simplifying assumptions about how black hole binaries evolve when they predict the strength of the stochastic gravitational wave background. By using information about galaxy mergers and constraints on the background, the scientists are able to improve their assumptions about black hole binary evolution.

    Ellis continues: “After nine years of observing a collection of MSPs, we haven’t detected the stochastic background but we are beginning to rule out many predictions based on current models of galaxy evolution. We are now at a point where the non-detection of gravitational waves is actually improving our understanding of black hole binary evolution.”

    “Pulsar timing arrays like NANOGrav are making novel observations of the evolution and nature of our Universe,” says Sarah Burke Spolaor, Jansky Fellow at the National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico, and a co-author on the paper.

    According to Spolaor, there are two possible interpretations of this non-detection. “Some supermassive black hole binaries may not be in circular orbits or are significantly interacting with gas or stars. This would drive them to merge faster than simple models have assumed in the past,” she said. An alternate explanation is that many of these binaries inspiral too slowly to ever emit detectable gravitational waves.

    NANOGrav is currently monitoring 54 pulsars, using the National Science Foundation’s Green Bank Telescope in West Virginia and Arecibo Radio Observatory in Puerto Rico, the two most sensitive radio telescopes at these frequencies [2]. Their array of pulsars is continually growing as new MSPs are discovered. In addition, the group collaborates with radio astronomers in Europe and Australia as part of the International Pulsar Timing Array, giving them access to many more pulsar observations. Ellis estimates that this increase in sensitivity could lead to a detection in as little as five years.

    In addition, this measurement helps constrain the properties of cosmic strings, very dense and thin cosmological objects, which many theorists believe evolved when the Universe was just a fraction of a second old. These strings can form loops, which then decay through gravitational wave emission. The most conservative NANOGrav limit on cosmic string tension is the most stringent limit to date, and will continue to improve as NANOGrav continues operating.

    “These new results from NANOGrav have the most important astrophysical implications yet,” said Scott Ransom, an astronomer with the NRAO in Charlottesville, Virginia. “As we improve our detection capabilities, we get closer and closer to that important threshold where the cosmic murmur begins to be heard. At that point, we’ll be able to perform entirely new types of physics experiments on cosmic scales and open up a new window on the Universe, just like LIGO just did for high-frequency gravitational waves.”

    NANOGrav is a collaboration of over 60 scientists at over a dozen institutions in the United States and Canada whose goal is detecting low-frequency gravitational waves to open a new window on the Universe. The group uses radio pulsar timing observations to search for the ripples in the fabric of spacetime. In 2015, NANOGrav was awarded $14.5 million by the National Science Foundation (NSF) to create and operate a Physics Frontiers Center.

    The Physics Frontier Centers bring people together to address frontier science, and NANOGrav’s work in low-frequency gravitational wave physics is a great example,” said Jean Cottam Allen, the NSF program director who oversees the Physics Frontiers Center program. “We’re delighted with their progress thus far, and we’re excited to see where it will lead.”

    1. # #

    Notes

    [1] LIGO is the Laser Interferometer Gravitational-Wave Observatory (https://www.ligo.caltech.edu)
    Press Release: Gravitational waves detected 100 years after Einstein’s prediction http://www.nsf.gov/news/news_summ.jsp?cntn_id=137628&org=NSF&from=news

    [2] National Science Foundation (http://www.nsf.gov)
    Press Release: Advancing physics frontiers: Newest collaborative centers set to blaze trails in basic research
    http://www.nsf.gov/news/news_summ.jsp?cntn_id=134586

    Reference:
    The NANOGrave Nine-year Data Set: Limits on the Isotropic Stochastic Gravitational Wave Background, Z. Arzoumanian et al., 2016, appears in the Astrophysical Journal http://iopscience.iop.org/journal/0004-637X.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), the Robert C. Byrd Green Bank Telescope (GBT), and the Very Long Baseline Array (VLBA)*.

    ALMA Array

    NRAO ALMA

    NRAO GBT
    NRAO GBT

    NRAO VLA
    NRAO VLA

    The NRAO is building two new major research facilities in partnership with the international community that will soon open new scientific frontiers: the Atacama Large Millimeter/submillimeter Array (ALMA), and the Expanded Very Large Array (EVLA). Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).
    *The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

    Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

     
  • richardmitnick 2:28 pm on March 29, 2016 Permalink | Reply
    Tags: , , Earth-Space Telescope System Produces Hot Surprise, NRAO,   

    From NRAO: “Earth-Space Telescope System Produces Hot Surprise” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    29 March 2016
    Dave Finley, Public Information Officer
    (575) 835-7302
    dfinley@nrao.edu

    1
    Artistic view of the 10-meter space radio telescope on the Russian satellite Spektr-R comprising the space-borne component of the RadioAstron mission.
    CREDIT: © Astro Space Center of Lebedev Physical Institute.

    Astronomers using an orbiting radio telescope in conjunction with four ground-based radio telescopes have achieved the highest resolution, or ability to discern fine detail, of any astronomical observation ever made. Their achievement produced a pair of scientific surprises that promise to advance the understanding of quasars, supermassive black holes at the cores of galaxies.

    The scientists combined the Russian RadioAstron satellite with the ground-based telescopes to produce a virtual radio telescope more than 100,000 miles across. They pointed this system at a quasar called 3C 273, more than 2 billion light-years from Earth. Quasars like 3C 273 propel huge jets of material outward at speeds nearly that of light. These powerful jets emit radio waves.

    2
    3C 273. From Hubble’s Wide Field and Planetary Camera 2 (WFPC2)

    NASA/ESA Hubble Telescope
    NASA/ESA Hubble Telescope

    NASA/Hubble WFPC2
    NASA/Hubble WFPC2. No longer in service
    Release 18 November 2013

    Just how bright such emission could be, however, was thought to be limited by physical processes. That limit, scientists thought, was about 100 billion degrees. The researchers were surprised when their Earth-space system revealed a temperature hotter then 10 trillion degrees.

    “Only this space-Earth system could reveal this temperature, and now we have to figure out how that environment can reach such temperatures,” said Yuri Kovalev, the RadioAstron project scientist. “This result is a significant challenge to our current understanding of quasar jets,” he added.

    The observations also showed, for the first time, substructure caused by scattering of the radio waves by the tenuous interstellar material in our own Milky Way Galaxy.

    “This is like looking through the hot, turbulent air above a candle flame,” said Michael Johnson, of the Harvard-Smithsonian Center for Astrophysics. “We had never been able to see such distortion of an extragalactic object before,” he added.

    “The amazing resolution we get from RadioAstron working with the ground-based telescopes gives us a powerful new tool to explore not only the extreme physics near the distant supermassive black holes, but also the diffuse material in our home Galaxy,” Johnson said.

    The RadioAstron satellite was combined with the Green Bank Telescope [GBT] in West Virginia, The Very Large Array [VLA] in New Mexico, the [MPIFR]Effelsberg Telescope in Germany, and the [NAIC]Arecibo Observatory in Puerto Rico.

    NRAO/GBT
    NRAO/GBT

    NRAO/VLA
    NRAO/VLA

    MPIFR/Effelsberg Radio Telescope
    MPIFR/Effelsberg Radio Telescope

    NAIC/Arecibo Observatory
    NAIC/Arecibo Observatory

    Signals received by the orbiting radio telescope were transmitted to an antenna in Green Bank where they were recorded and then sent over the internet to Russia where they were combined with the data received by the ground-based radio telescopes to form the high resolution image of 3C 273.

    5
    Artistic view of a quasar; a super-massive black hole in the center is being fed by a disk of gas and dust, producing collimated jets of ejected material moving at nearly the speed of light.
    © Wolfgang Steffen, Institute for Astronomy, UNAM, Mexico

    The astronomers reported their results in the Astrophysical Journal Letters.

    In 1963, astronomer Maarten Schmidt of Caltech recognized that a visible-light spectrum of 3C 273 indicated its great distance, resolving what had been a mystery about quasars. His discovery showed that the objects are emitting tremendous amounts of energy and led to the current model of powerful emission driven by the tremendous gravitational energy of a supermassive black hole.

    The RadioAstron project is led by the Astro Space Center of the Lebedev Physical Institute of the Russian Academy of Sciences and the Lavochkin Scientific and Production Association under a contract with the Russian Federal Space Agency, in collaboration with partner organizations in Russia and other countries. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

    Science papers:
    RadioAstron Observations of the Quasar 3C273: a Challenge to the Brightness Temperature Limit
    Y. Y. Kovalev (ASC Lebedev, MPIfR), N. S. Kardashev (ASC Lebedev), K. I. Kellermann (NRAO), A. P. Lobanov (MPIfR, U Hamburg), M. D. Johnson (Harvard-Smithsonian CfA), L. I. Gurvits (JIVE, Delft U), P. A. Voitsik (ASC Lebedev), J. A. Zensus (MPIfR), J. M. Anderson (MPIfR, Helmholtz-Zentrum Potsdam), U. Bach (MPIfR), D. L. Jauncey (CSIRO, ANU Canberra), F. Ghigo (NRAO), T. Ghosh (Arecibo), A. Kraus (MPIfR), Yu. A. Kovalev (ASC Lebedev), M. M. Lisakov (ASC Lebedev), L. Yu. Petrov (Astrogeo Center), J. D. Romney (NRAO), C. J. Salter (Arecibo), K. V. Sokolovsky (ASC Lebedev, SAI MSU)

    Extreme Brightness Temperatures and Refractive Substructure in 3C273 with RadioAstron
    Michael D. Johnson (Harvard-Smithsonian CfA), Yuri Y. Kovalev (ASC Lebedev, MPIfR), Carl R. Gwinn (UCSB), Leonid I. Gurvits (JIVE, Delft U), Ramesh Narayan (Harvard-Smithsonian CfA), Jean-Pierre Macquart (ICRAR/Curtin, CAASTRO), David L. Jauncey (CSIRO, ANU Canberra), Peter A. Voitsik (ASC Lebedev), James M. Anderson (Helmholtz-Zentrum Potsdam, MPIfR), Kirill V. Sokolovsky (ASC Lebedev, SAI MSU), Mikhail M. Lisakov (ASC Lebedev)

    In the science papers, you can read all about the project.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), the Robert C. Byrd Green Bank Telescope (GBT), and the Very Long Baseline Array (VLBA)*.

    ALMA Array

    NRAO ALMA

    NRAO GBT
    NRAO GBT

    NRAO VLA
    NRAO VLA

    The NRAO is building two new major research facilities in partnership with the international community that will soon open new scientific frontiers: the Atacama Large Millimeter/submillimeter Array (ALMA), and the Expanded Very Large Array (EVLA). Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).
    *The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

    Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

     
  • richardmitnick 6:59 pm on March 24, 2016 Permalink | Reply
    Tags: , , NRAO,   

    From NRAO: “NRAO Structural Changes: Announcing the Separation of the Green Bank Observatory and the Long Baseline Observatory” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    3.24.16
    Tony Beasley (NRAO Director) and Ethan Schreier (AUI President)

    On 20 November 2015, the National Science Foundation (NSF) selected Associated Universities, Inc. (AUI) to manage the National Radio Astronomy Observatory (NRAO) through a new 10-year cooperative agreement. The new agreement includes the operation of the Karl G. Jansky Very Large Array (VLA), the North American share of the international Atacama Large Millimeter/submillimeter Array (ALMA), and NRAO’s development laboratories and administrative and management functions, effective 1 October 2016.

    NRAO/VLA
    NRAO/VLA

    ESO/NRAO/NAOJ ALMA Array
    ESO/NRAO/NAOJ ALMA Array

    The Green Bank Telescope (GBT) and Very Long Baseline Array (VLBA), which were recommended for divestment several years ago, will exit NRAO and become independent facilities known as the Green Bank Observatory (GBO), with Karen O’Neil as its director, and the Long Baseline Observatory (LBO), with Walter Brisken as its director. Pending submission, review, and approval of a supplemental funding request, AUI will continue managing each under a separate cooperative agreement for the next two years, while NSF decides the long-term future of these facilities.

    GBO
    GBO

    LBO
    LBO

    This new arrangement has a number of advantages, and provides the needed independence and flexibility for GBO and LBO to continue to serve the national and international science communities while actively building new partnerships. Looking to the future, NRAO will work closely with its users and the broader scientific community to identify, develop, and effectively deploy new capabilities across a broader range of discovery space in combination with GBO and LBO.

    Observing proposal submission, science operations, and user support for the GBT and VLBA science communities will continue unchanged in the near term as NSF and AUI explore details and options for the Fiscal Year 2017 launch of the GBO and LBO.

    We look forward to the continued success of NRAO and the new opportunities GBO and LBO bring to the astronomy community.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), the Robert C. Byrd Green Bank Telescope (GBT), and the Very Long Baseline Array (VLBA)*.

    ALMA Array

    NRAO ALMA

    NRAO GBT
    NRAO GBT

    NRAO VLA
    NRAO VLA

    The NRAO is building two new major research facilities in partnership with the international community that will soon open new scientific frontiers: the Atacama Large Millimeter/submillimeter Array (ALMA), and the Expanded Very Large Array (EVLA). Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).
    *The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

    Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

     
  • richardmitnick 3:42 pm on August 6, 2015 Permalink | Reply
    Tags: , , , NRAO   

    From NRAO: “Gravitational Constant Appears Universally Constant, Pulsar Study Suggests” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    August 6, 2015
    Contact: Charles E. Blue
    (434) 296-0314; cblue@nrao.edu

    1
    A 21-year study of a pair of ancient stars — one a pulsar and the other a white dwarf — helps astronomers understand how gravity works across the cosmos. The study was conducted with the NSF’s Green Bank Telescope and the Arecibo Observatory. Credit: B. Saxton (NRAO/AUI/NSF)

    Gravity, one of the four fundamental forces of nature, appears reassuringly constant across the Universe, according to a decades-long study of a distant pulsar. This research helps to answer a long-standing question in cosmology: Is the force of gravity the same everywhere and at all times? The answer, so far, appears to be yes.

    Astronomers using the National Science Foundation’s (NSF) Green Bank Telescope (GBT) in West Virginia and its Arecibo Observatory in Puerto Rico conducted a 21-year study to precisely measure the steady “tick-tick-tick” of a pulsar known as PSR J1713+0747.

    1
    GBT

    Arecibo
    Arecibo Observatory

    This painstaking research produced the best constraint ever of the gravitational constant measured outside of our Solar System.

    Pulsars are the rapidly spinning, superdense remains of massive stars that detonated as supernovas. They are detected from Earth by the beams of radio waves that emanate from their magnetic poles and sweep across space as the pulsar rotates. Since they are phenomenally dense and massive, yet comparatively small – a mere 20–25 kilometers across – some pulsars are able to maintain their rate of spin with a consistency that rivals the best atomic clocks on Earth. This makes pulsars exceptional cosmic laboratories to study the fundamental nature of space, time, and gravity.

    This particular pulsar is approximately 3,750 light-years from Earth. It orbits a companion white dwarf star and is one of the brightest, most stable pulsars known. Previous studies show that it takes about 68 days for the pulsar to orbit its white dwarf companion, meaning they share an uncommonly wide orbit. This separation is essential for the study of gravity because the effect of gravitational radiation – the steady conversion of orbital velocity to gravitational waves as predicted by [Albert]Einstein – is incredibly small and would have negligible impact on the orbit of the pulsar. A more pronounced orbital change would confound the accuracy of the pulsar timing experiment.

    “The uncanny consistency of this stellar remnant offers intriguing evidence that the fundamental force of gravity – the big ‘G’ of physics – remains rock-solid throughout space,” said Weiwei Zhu, an astronomer formerly with the University of British Columbia in Canada and lead author on a study accepted for publication in the Astrophysical Journal. “This is an observation that has important implications in cosmology and some of the fundamental forces of physics.”

    “Gravity is the force that binds stars, planets, and galaxies together,” said Scott Ransom, a co-author and astronomer with the National Radio Astronomy Observatory in Charlottesville, Va. “Though it appears on Earth to be constant and universal, there are some theories in cosmology that suggest gravity may change over time or may be different in different corners of the Universe.”

    The data taken throughout this experiment are consistent with an unchanging gravitational constant in a distant star system. Earlier related research in our own Solar System, which was based on precise laser ranging studies of the Earth-Moon distance, found the same consistency over time.

    “These results – new and old – allow us to rule out with good confidence that there could be ‘special’ times or locations with different gravitational behavior,” added Ingrid Stairs, a co-author from the University of British Columbia in Canada. “Theories of gravity that are different from general relativity often make such predictions, and we have put new restrictions on the parameters that describe these theories.”

    Zhu concluded: “The gravitational constant is a fundamental constant of physics, so it is important to test this basic assumption using objects at different places, times, and gravitational conditions. The fact that we see gravity perform the same in our Solar System as it does in a distant star system helps to confirm that the gravitational constant truly is universal.”

    This work was part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), a Physics Frontiers Center funded by the NSF.

    The GBT is located in the National Radio Quiet Zone, which protects the incredibly sensitive telescope from unwanted radio interference, enabling it to study pulsars and other astronomical objects.

    The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), the Robert C. Byrd Green Bank Telescope (GBT), and the Very Long Baseline Array (VLBA)*.

    ALMA Array

    NRAO ALMA

    NRAO GBT
    NRAO GBT

    NRAO VLA
    NRAO VLA

    The NRAO is building two new major research facilities in partnership with the international community that will soon open new scientific frontiers: the Atacama Large Millimeter/submillimeter Array (ALMA), and the Expanded Very Large Array (EVLA). Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).
    *The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

    Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

     
  • richardmitnick 6:59 am on August 4, 2015 Permalink | Reply
    Tags: , , , , NRAO,   

    From NRAO: “Neutron Stars Strike Back at Black Holes in Jet Contest” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    4 August 2015
    Dave Finley, Public Information Officer
    (575) 835-7302
    dfinley@nrao.edu

    1
    Artist’s impression of material flowing from a companion star onto a neutron star. The material forms an accretion disk around the neutron star and produces a superfast jet of ejected material. The material closest to the neutron star is so hot that it glows in X-rays, while the jet is most prominent at radio wavelengths. A similar mechanism is at work with black holes. CREDIT: Bill Saxton, NRAO/AUI/NSF.

    Some neutron stars may rival black holes in their ability to accelerate powerful jets of material to nearly the speed of light, astronomers using the Karl G. Jansky Very Large Array (VLA) have discovered.

    “It’s surprising, and it tells us that something we hadn’t previously suspected must be going on in some systems that include a neutron star and a more-normal companion star,” said Adam Deller, of ASTRON, the Netherlands Institute for Radio Astronomy.

    Black holes and neutron stars are respectively the densest and second most dense forms of matter known in the Universe. In binary systems where these extreme objects orbit with a more normal companion star, gas can flow from the companion to the compact object, producing spectacular displays when some of the material is blasted out in powerful jets at close to the speed of light

    Previously, black holes were the undisputed kings of forming powerful jets. Even when only nibbling on a small amount of material, the radio emission that traces the jet outflow from the black hole was relatively bright. In comparison, neutron stars seemed to make relatively puny jets — the radio emission from their jets was only bright enough to see when they were gobbling material from their companion at a very high rate. A neutron star sedately consuming material was therefore predicted to form only very weak jets, which would be too faint to observe.

    Recently, however, combined radio and X-ray observations of the neutron star PSR J1023+0038 completely contradicted this picture. PSR J1023+0038, which was discovered by ASTRON astronomer Anne Archibald in 2009, is the prototypical “transitional millisecond pulsar”– a neutron star which spends years at a time in a non-accreting state, only to “transition” occasionally into active accretion. When observed in 2013 and 2014, it was accreting only a trickle of material, and should have been producing only a feeble jet.

    “Unexpectedly, our radio observations with the Very Large Array showed relatively strong emission, indicating a jet that is nearly as strong as we would expect from a black hole system,” Deller said.

    NRAO VLA
    VLA

    Two other such “transitional” systems are now known, and both of these now have been shown to exhibit powerful jets that rival those of their black-hole counterparts. What makes these transitional systems special compared to their other neutron star brethren? For that, Deller and colleagues are planning additional observations of known and suspected transitional systems to refine theoretical models of the accretion process.

    Deller led a team of astronomers who reported their findings in the Astrophysical Journal.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), the Robert C. Byrd Green Bank Telescope (GBT), and the Very Long Baseline Array (VLBA)*.

    ALMA Array

    NRAO ALMA

    NRAO GBT
    NRAO GBT

    NRAO VLA
    NRAO VLA

    The NRAO is building two new major research facilities in partnership with the international community that will soon open new scientific frontiers: the Atacama Large Millimeter/submillimeter Array (ALMA), and the Expanded Very Large Array (EVLA). Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).
    *The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

    Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

     
  • richardmitnick 12:16 pm on January 28, 2015 Permalink | Reply
    Tags: , , NRAO,   

    From NRAO: “New Bolometer Camera Deployed on GBT” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    Jan 28, 2015
    B. Mason (NRAO), S. Dicker, S. Stanchfield & M. Devlin (U. Penn)

    1
    The MUSTANG-2 array of 223 feed horns, which are machined out of a single aluminum block that has been gold-coated. Dual-polarization detector modules are affixed to each feed.

    In December 2014, a new bolometer camera (MUSTANG-2) was installed on the NRAO Green Bank Telescope (GBT). This camera employs many of the technologies used in its predecessor – MUSTANG, used by GBT observers from 2009 to 2013 – including Transition Edge Sensor (TES) bolometers; Superconducting QUantum Interference Device (SQUID) amplifiers to read out the detectors; a low-vibration pulse tube refrigerator; and closed-cycle helium-3 and helium-4 refrigerators to cool the detectors to 300 mK.

    MUSTANG-2 features many improvements: more sensitive microstrip- and feedhorn-coupled TES bolometers; a wider (75-105 GHz) band pass; a 5x larger instantaneous field-of-view; and much more robust cryogenic performance. Readout is accomplished via four ROACH boards using a microwave-resonator multiplexer that has been adapted for use with TES detectors. The receiver has been designed to accommodate 223 dual-polarization detectors, and the full 223 feedhorn detector array has been fabricated and deployed on the GBT (Figure 1). Available funding permitted populating only 64 of the 223 feeds; the current version of the instrument has thus been dubbed MUSTANG-1.5.

    Similar to its predecessor, MUSTANG-2 will have a ~8.5″ (FWHM) beam when used on the GBT. It is available for early science observing in collaboration with the instrument team. Commissioning is ongoing and we expect that early science observing will begin in late January 2015. MUSTANG-2 will excel at making high-resolution images of the Sunyaev-Zel’dovich effect, and mapping the large-scale context of star formation in our own Galaxy and nearby galaxies.

    See the full article here.

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    The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), the Robert C. Byrd Green Bank Telescope (GBT), and the Very Long Baseline Array (VLBA)*.

    NRAO ALMA
    NRAO ALMA

    NRAO GBT
    NRAO GBT

    NRAO VLA
    NRAO VLA

    The NRAO is building two new major research facilities in partnership with the international community that will soon open new scientific frontiers: the Atacama Large Millimeter/submillimeter Array (ALMA), and the Expanded Very Large Array (EVLA). Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).
    *The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

    Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

     
  • richardmitnick 12:59 pm on January 8, 2014 Permalink | Reply
    Tags: , , , , NRAO,   

    From NRAO: “Dwarf Galaxies Give Clues to Origin of Supermassive Black Holes” 

    NRAO Icon
    National Radio Astronomy Observatory

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    Monday, 6 January 2014
    Contact: Dave Finley, Public Information Officer
    (575) 835-7302; dfinley@nrao.edu

    Poring through data from a large sky survey, astronomers have found more than 100 small, dwarf galaxies with characteristics indicating that they harbor massive black holes feeding on surrounding gas. The discovery confounds a common assumption that only much larger galaxies hold such monsters, and may help resolve the question of how such black holes originated and grew in the early Universe.

    uni
    Dwarf galaxy NGC 4395, about 13 million light-years from Earth, known to harbor a black hole some 300,000 times more massive than the Sun. It is a prototypical example of a small galaxy once thought to be too small to contain such a black hole.
    CREDIT: David W. Hogg, Michael R. Blanton, and the Sloan Digital Sky Survey Collaboration; NRAO/AUI/NSF.

    Another view
    image
    An ultraviolet image of NGC 4395 taken with GALEX.
    Credit: GALEX/NASA

    “We’ve shown that even small galaxies can have massive black holes and that they may be more common than previously thought,” said Amy Reines, of the National Radio Astronomy Observatory (NRAO). “This is really exciting because these little galaxies hold the clues to the origin of the first ‘seeds’ of supermassive black holes in the early Universe,” she said. Reines and her colleagues presented their findings to the American Astronomical Society’s meeting in Washington, DC.

    Black holes are concentrations of mass so dense that not even light can escape their gravitational pull. Nearly all “full-sized” galaxies are known to have supermassive black holes, millions or billions of times more massive than the Sun, at their cores. Until recently, however, smaller galaxies were thought not to harbor massive black holes.

    Reines, along with Jenny Greene of Princeton University and Marla Geha of Yale University, analyzed data from the Sloan Digital Sky Survey, and found more than 100 dwarf galaxies whose patterns of light emission indicated the presence of massive black holes and their feeding process.

    “The galaxies are comparable in size to the Magellanic Clouds, dwarf satellite galaxies of the Milky Way,” Geha said. “Previously, such galaxies were thought to be too small to have such massive black holes,” she added.

    In the nearby Universe, astronomers have found a direct relationship between the mass of a galaxy’s central black hole and a “bulge” in its center. This indicates that the black holes and the bulges may have affected each others’ growth.

    “Finding these small galaxies with massive black holes is an important step toward understanding how galaxies and black holes developed together,” Greene said. “These dwarf galaxies are the smallest known to host massive black holes and can provide clues to how supermassive black holes get started in the first place,” she added.

    While today’s larger galaxies hold black holes millions or billions of times more massive than the Sun, the dwarf galaxies in the new study have black holes roughly 100,000 times the Sun’s mass. The supermassive and massive black holes are distinct from stellar-mass black holes — only a few times the mass of the Sun — that result from the collapse of a massive star at the end of its “normal” life.

    Still unknown, the scientists said, is whether the massive black holes initially began as the remnants of extremely massive early stars or some other scenario of collapsing mass.

    “Getting a good census of dwarf galaxies with massive black holes is an important first step to resolving this question,” Reines said.

    See the full article here.

    The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), the Robert C. Byrd Green Bank Telescope (GBT), and the Very Long Baseline Array (VLBA)*.

    NRAO ALMA
    NRAO ALMA

    NRAO GBT
    NRAO GBT

    NRAO VLA
    NRAO VLA

    The NRAO is building two new major research facilities in partnership with the international community that will soon open new scientific frontiers: the Atacama Large Millimeter/submillimeter Array (ALMA), and the Expanded Very Large Array (EVLA). Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).
    *The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

    Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.


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  • richardmitnick 1:47 pm on September 5, 2013 Permalink | Reply
    Tags: , , , , NRAO   

    From NRAO: “Powerful Jets Blowing Material Out of Galaxy” 

    NRAO Icon
    National Radio Astronomy Observatory

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    5 September 2013
    Dave Finley, Public Information Officer
    Socorro, NM
    (575) 835-7302
    dfinley@nrao.edu

    Astronomers using a worldwide network of radio telescopes have found strong evidence that a powerful jet of material propelled to nearly light speed by a galaxy’s central black hole is blowing massive amounts of gas out of the galaxy. This process, they said, is limiting the growth of the black hole and the rate of star formation in the galaxy, and thus is a key to understanding how galaxies develop.

    graph
    Radio-Telescope Image of Galaxy 4C12.50

    Astronomers have theorized that many galaxies should be more massive and have more stars than is actually the case. Scientists proposed two major mechanisms that would slow or halt the process of mass growth and star formation — violent stellar winds from bursts of star formation and pushback from the jets powered by the galaxy’s central, supermassive black hole.

    “With the finely-detailed images provided by an intercontinental combination of radio telescopes, we have been able to see massive clumps of cold gas being pushed away from the galaxy’s center by the black-hole-powered jets,” said Raffaella Morganti, of the Netherlands Institute for Radio Astronomy and the University of Groningen.

    The scientists studied a galaxy called 4C12.50, nearly 1.5 billion light-years from Earth. They chose this galaxy because it is at a stage where the black-hole “engine” that produces the jets is just turning on. As the black hole, a concentration of mass so dense that not even light can escape, pulls material toward it, the material forms a swirling disk surrounding the black hole. Processes in the disk tap the tremendous gravitational energy of the black hole to propel material outward from the poles of the disk.

    At the ends of both jets, the researchers found clumps of hydrogen gas moving outward from the galaxy at 1,000 kilometers per second. One of the clouds has much as 16,000 times the mass of the Sun, while the other contains 140,000 times the mass of the Sun. The larger cloud, the scientists said, is roughly 160 by 190 light-years in size.

    “This is the most definitive evidence yet for an interaction between the swift-moving jet of such a galaxy and a dense interstellar gas cloud,” Morganti said. “We believe we are seeing in action the process by which an active, central engine can remove gas –the raw material for star formation — from a young galaxy,” she added.

    The scientists also said their observations indicate that the jets from the galaxy’s core can stretch and deform clouds of interstellar gas to expand their “pushing” effect beyond the narrow width of the jets themselves. In addition, they reported that, at 4C12.50’s stage of development, the jets may turn on and off and so periodically repeat the process of removing gas from the galaxy.

    Morganti and her team used radio telescopes in Europe and the U.S., combining their signals to make one giant, intercontinental telescope. In the U.S., these included the National Science Foundation’s Very Long Baseline Array (VLBA), a continent-wide system of radio telescopes ranging from Hawaii, across the U.S. mainland, to St. Croix in the Virgin Islands, and one antenna from the Karl G. Jansky Very Large Array (VLA) in New Mexico. The European radio telescopes they used are in Effelsberg, Germany; Westerbork, the Netherlands; and Onsala, Sweden. The extremely high resolving power, or ability to see fine detail, provided by such a far-flung system was essential to pinpointing the location of the gas clouds affected by the galaxy’s jets.

    See the full article here.

    The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), the Robert C. Byrd Green Bank Telescope (GBT), and the Very Long Baseline Array (VLBA)*.

    NRAO ALMA
    NRAO ALMA

    NRAO GBT
    NRAO GBT

    NRAO VLA
    NRAO VLA

    The NRAO is building two new major research facilities in partnership with the international community that will soon open new scientific frontiers: the Atacama Large Millimeter/submillimeter Array (ALMA), and the Expanded Very Large Array (EVLA). Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).
    *The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

    Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

     
  • richardmitnick 3:26 pm on July 18, 2013 Permalink | Reply
    Tags: , , , , , , NRAO   

    From ESO: “Snow in an Infant Planetary System” 

    A frosty landmark for planet and comet formation

    18 July 2013

    Contacts
    Chunhua Qi
    Harvard-Smithsonian Center for Astrophysics
    Cambridge, Mass., USA
    Tel: +1 617 495 7087
    Email: cqi@cfa.harvard.edu

    Michiel Hogerheijde
    Leiden Observatory
    Leiden, The Netherlands
    Tel: +31 6 4308 3291
    Email: michiel@strw.leidenuniv.nl

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

    “A snow line has been imaged in a far-off infant planetary system for the very first time. The snow line, located in the disc around the Sun-like star TW Hydrae, promises to tell us more about the formation of planets and comets, the factors that decide their composition, and the history of the Solar System. The results are published today in Science Express.

    snow
    Artist’s impression

    Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have taken the first ever image of the snow line in an infant planetary system. On Earth, snow lines form at high altitudes where falling temperatures turn the moisture in the air into snow. This line is clearly visible on a mountain, where the snow-capped summit ends and the rocky face begins.

    The snow lines around young stars form in a similar way, in the distant, colder reaches of the dusty discs from which planetary systems form. Starting from the star and moving outwards, water (H2O) is the first to freeze, forming the first snow line. Further out from the star, as temperatures drop, more exotic molecules can freeze and turn to snow, such as carbon dioxide (CO2), methane (CH4), and carbon monoxide (CO). These different snows give the dust grains a sticky outer coating and play an essential role in helping the grains to overcome their usual tendency to break up in collisions, allowing them to become the crucial building blocks of planets and comets. The snow also increases how much solid matter is available and may dramatically speed up the planetary formation process.

    Each of these different snow lines — for water, carbon dioxide, methane and carbon monoxide — may be linked to the formation of particular kinds of planets. Around a Sun-like star in a planetary system like our own, the water snow line would correspond to a distance between the orbits of Mars and Jupiter, and the carbon monoxide snow line would correspond to the orbit of Neptune.

    The snow line spotted by ALMA is the first glimpse of the carbon monoxide snow line, around TW Hydrae, a young star 175 light-years away from Earth. Astronomers believe this budding planetary system shares many of the same characteristics of the Solar System when it was just a few million years old.

    The team is composed of C. Qi (Harvard-Smithsonian Center for Astrophysics, USA), K. I. Öberg (Departments of Chemistry and Astronomy, University of Virginia, USA), D. J. Wilner (Harvard-Smithsonian Center for Astrophysics, USA), P. d’Alessio (Centro de Radioastronomía y Astrofisica, Universidad Nacional Autónoma de Mexico, Mexico), E. Bergin (Department of Astronomy, University of Michigan, USA), S. M. Andrews (Harvard-Smithsonian Center for Astrophysics, USA), G. A. Blake (Division of Geological and Planetary Sciences, California Institute of Technology, USA), M. R. Hogerheijde (Leiden Observatory, Leiden University, Netherlands) and E. F. van Dishoeck (Max Planck Institute for Extraterrestrial Physics, Germany).

    See the full article here, with notes.

    NRAO news release

    Qi and Öberg were joint lead authors of this work.

    ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.
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    ALMA Atacama Large Millimeter/submillimeter Array

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  • richardmitnick 2:05 pm on May 9, 2013 Permalink | Reply
    Tags: , , , , Green Bank, NRAO, ,   

    From NRAO: “Astronomers Discover Surprising Clutch of Hydrogen Clouds Lurking among Our Galactic Neighbors” 

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    “In a dark, starless patch of intergalactic space, astronomers have discovered a never-before-seen cluster of hydrogen clouds strewn between two nearby galaxies, Andromeda (M31) and Triangulum (M33). The researchers speculate that these rarefied blobs of gas — each about as massive as a dwarf galaxy — condensed out of a vast and as-yet undetected reservoir of hot, ionized gas, which could have accompanied an otherwise invisible band of dark matter.

    gas
    Intergalactic clouds between Andromeda and Triangulum galaxies

    The astronomers detected these objects using the National Science Foundation’s Green Bank Telescope (GBT) at the National Radio Astronomy Observatory (NRAO) in Green Bank, W.Va. The results were published in the journal Nature.

    ‘We have known for some time that many seemingly empty stretches of the Universe contain vast but diffuse patches of hot, ionized hydrogen,’ said Spencer Wolfe of West Virginia University in Morgantown. ‘Earlier observations of the area between M31 and M33 suggested the presence of colder, neutral hydrogen, but we couldn’t see any details to determine if it had a definitive structure or represented a new type of cosmic feature. Now, with high-resolution images from the GBT, we were able to detect discrete concentrations of neutral hydrogen emerging out of what was thought to be a mainly featureless field of gas.'”

    See the full article here.

    NRAO ALMA
    NRAO ALMA

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    The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), the Robert C. Byrd Green Bank Telescope (GBT), and the Very Long Baseline Array (VLBA)*.

    The NRAO is building two new major research facilities in partnership with the international community that will soon open new scientific frontiers: the Atacama Large Millimeter/submillimeter Array (ALMA), and the Expanded Very Large Array (EVLA). Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).

    *The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

    Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

     
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