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  • richardmitnick 1:44 pm on July 6, 2017 Permalink | Reply
    Tags: , , , , , NRAO, , VLA Gives New Insight Into Galaxy Cluster’s Spectacular 'Mini-Halo'   

    From NRAO: “VLA Gives New Insight Into Galaxy Cluster’s Spectacular ‘Mini-Halo'” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    June 13, 2017
    Dave Finley, Public Information Officer
    (575) 835-7302
    dfinley@nrao.edu

    1

    Astronomers using the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) have discovered new details that are helping them decipher the mystery of how giant radio-emitting structures are formed at the center of a cluster of galaxies.

    The scientists studied a cluster of thousands of galaxies more than 250 million light-years from Earth, named the Perseus Cluster after the constellation in which it appears. Embedded within the center, the Perseus Cluster hosts a pool of superfast particles that emit radio waves, creating a radio structure known as a “mini-halo.” Mini-haloes have been found in about 30 galaxy clusters, but the halo in the Perseus Cluster is the largest known, about 1.3 million light-years in diameter, or 10 times the size of our Milky Way Galaxy.

    The sizes of the mini-haloes have presented a puzzle to astronomers. As the particles travel away from the cluster’s center, they should slow down and stop emitting radio waves long before they reach the distances observed, according to theory.

    “At large distances from the central galaxy, we don’t expect to be able to see these haloes,” said Marie-Lou Gendron-Marsolais, of the University of Montreal. “However, we do see them and we want to know why,” she added.

    The astronomers took advantage of the upgraded capabilities of the VLA to make new images of the Perseus Cluster that were both more sensitive to fainter radio emissions and provided higher resolution than previous radio observations.

    “The new VLA images provided an unprecedented view of the mini-halo by revealing a multitude of new structures within it,” said Julie Hlavacek-Larrondo, also of the University of Montreal. “These structures tell us that the origin of the radio emission is not as simple as we thought,” she said.

    The new details indicate that the halo’s radio emission is caused by complex mechanisms that vary throughout the cluster. As theorized before, some radio emission is caused by particles being reaccelerated when small groups of galaxies collide with the cluster and give the particles a gravitational shove. In addition, however, the scientists now think that the radio emission is also caused by the powerful jets of particles generated by the supermassive black hole at the core of the central galaxy that give an extra “kick” of energy to the particles.

    “This would help explain the rich variety of complex structures that we see,” Gendron-Marsolais said.

    “The high-quality images that the upgraded VLA can produce will be key to helping us gain new insights into these mini-haloes in our quest to understand their origin,” Hlavacek-Larrondo said.

    The VLA, built during the 1970s, was equipped with all-new electronics to bring it up to the technological state of the art by a decade-long project completed in 2012. The images of the Perseus Cluster were made using a new low frequency receiver system funded by the Naval Research Laboratory (NRL) and built through collaboration between NRL and the National Radio Astronomy Observatory.

    Gendron-Marsolais and Hlavacek-Larrondo, along with an international team of researchers, are reporting their findings in the Monthly Notices of the Royal Astronomical Society.

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

    NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

    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), and the Very Long Baseline Array (VLBA)*.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).

    NRAO VLBA

    NRAO VLBA

    *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.

    And the future Expanded Very Large Array (EVLA).

     
  • richardmitnick 9:21 pm on June 27, 2017 Permalink | Reply
    Tags: Astronomers Detect Orbital Motion in Pair of Supermassive Black Holes, Elliptical galaxy called 0402+379, NRAO, NSF/VLBA - Very Long Baseline Array, Visual binary   

    From NRAO: “Astronomers Detect Orbital Motion in Pair of Supermassive Black Holes” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    June 27, 2017
    Media Contact:
    Dave Finley, Public Information Officer
    (575) 835-7302
    dfinley@nrao.edu

    VLBA reveals first-ever black-hole “visual binary”

    NRAO VLBA

    2
    Artist’s conception of the pair of supermassive black holes at the center of the galaxy 0402+379, 750 million light-years from Earth.. Credit: Josh Valenzuela/University of New Mexico

    3
    VLBA image of the central region of the galaxy 0402+379, showing the two cores, labeled C1 and C2, identified as a pair of supermassive black holes in orbit around each other. Credit: Bansal et al., NRAO/AUI/NSF.

    Using the supersharp radio “vision” of the National Science Foundation’s Very Long Baseline Array (VLBA), astronomers have made the first detection of orbital motion in a pair of supermassive black holes in a galaxy some 750 million light-years from Earth.

    The two black holes, with a combined mass 15 billion times that of the Sun, are likely separated by only about 24 light-years, extremely close for such a system.

    “This is the first pair of black holes to be seen as separate objects that are moving with respect to each other, and thus makes this the first black-hole ‘visual binary,’” said Greg Taylor, of the University of New Mexico (UNM).

    Supermassive black holes, with millions or billions of times the mass of the Sun, reside at the cores of most galaxies. The presence of two such monsters at the center of a single galaxy means that the galaxy merged with another some time in the past. In such cases, the two black holes themselves may eventually merge in an event that would produce gravitational waves that ripple across the universe.

    “We believe that the two supermassive black holes in this galaxy will merge,” said Karishma Bansal, a graduate student at UNM, adding that the merger will come at least millions of years in the future.

    The galaxy, an elliptical galaxy called 0402+379, after its location in the sky, was first observed in 1995. It was studied in 2003 and 2005 with the VLBA. Based on finding two cores in the galaxy, instead of one, Taylor and his collaborators concluded in 2006 that it contained a pair of supermassive black holes.

    The latest research, which Taylor and his colleagues are reporting in the Astrophysical Journal, incorporates new VLBA observations from 2009 and 2015, along with re-analysis of the earlier VLBA data. This work revealed motion of the two cores, confirming that the two black holes are orbiting each other. The scientists’ initial calculations indicate that they complete a single orbit in about 30,000 years.

    “We need to continue observing this galaxy to improve our understanding of the orbit, and of the masses of the black holes,” Taylor said. “This pair of black holes offers us our first chance to study how such systems interact,” he added.

    The astronomers also hope to discover other such systems. The galaxy mergers that bring two supermassive black holes close together are considered to be a common process in the universe, so astronomers expect that such binary pairs should be common.

    “Now that we’ve been able to measure orbital motion in one such pair, we’re encouraged to seek other, similar pairs. We may find others that are easier to study,” Bansal said.

    The VLBA, part of the Long Baseline Observatory, is a continent-wide radio telescope system using ten, 240-ton dish antennas distributed from Hawaii to St. Croix in the Caribbean. All ten antennas work together as a single telescope with the greatest resolving power available to astronomy. That extraordinary resolving power allows scientists to make extremely fine measurements of objects and motions in the sky, such as those done for the research on 0402+379.

    The Long Baseline 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), and the Very Long Baseline Array (VLBA)*.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).

    NRAO VLBA

    NRAO VLBA

    *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.

    And the future Expanded Very Large Array (EVLA).

     
  • richardmitnick 2:41 pm on April 12, 2017 Permalink | Reply
    Tags: , , , , , NRAO, Planetary body 2014 UZ224 more informally known as DeeDee,   

    From ALMA: “ALMA Investigates ‘DeeDee,’ a Distant, Dim Member of Our Solar System” 

    ESO/NRAO/NAOJ ALMA Array
    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres
    ALMA

    April 12, 2017
    Nicolás Lira T.
    Press Coordinator
    Joint ALMA Observatory
    Santiago, Chile
    Tel: +56 2 24 67 65 19
    Cell: +56 9 94 45 77 26
    Email: nicolas.lira@alma.cl

    Charles E. Blue
    Public Information Officer
    National Radio Astronomy Observatory
    Charlottesville, Virginia, USA
    Tel: +1 434 296 0314
    Cell: +1 202 236 6324
    E-mail: cblue@nrao.edu

    Richard Hook
    Public Information Officer, ESO

    Garching bei München, Germany

    Tel: +49 89 3200 6655

    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    Masaaki Hiramatsu

    Education and Public Outreach Officer, NAOJ Chile
    Observatory
Tokyo, Japan

    Tel: +81 422 34 3630

    E-mail: hiramatsu.masaaki@nao.ac.jp
    1
    Artist concept of the planetary body 2014 UZ224, more informally known as DeeDee. ALMA was able to observe the faint millimeter-wavelength “glow” emitted by the object, confirming it is roughly 635 kilometers across. At this size, DeeDee should have enough mass to be spherical, the criterion necessary for astronomers to consider it a dwarf planet, though it has yet to receive that official designation. Credit: Alexandra Angelich (NRAO/AUI/NSF)

    Using the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers have revealed extraordinary details about a recently discovered far-flung member of our solar system, the planetary body 2014 UZ224, more informally known as DeeDee.

    2
    ALMA image of the faint millimeter-wavelength “glow” from the planetary body 2014 UZ224, more informally known as DeeDee. At three times the distance of Pluto from the Sun, DeeDee is the second most distant known TNO with a confirmed orbit in our solar system. Credit: ALMA (ESO/NAOJ/NRAO)

    At about three times the current distance of Pluto from the Sun, DeeDee is the second most distant known trans-Neptunian object (TNO) with a confirmed orbit, surpassed only by the dwarf planet Eris. Astronomers estimate that there are tens-of-thousands of these icy bodies in the outer solar system beyond the orbit of Neptune.

    The new ALMA data reveal, for the first time, that DeeDee is roughly 635 kilometers across, or about two-thirds the diameter of the dwarf planet Ceres, the largest member of our asteroid belt. At this size, DeeDee should have enough mass to be spherical, the criterion necessary for astronomers to consider it a dwarf planet, though it has yet to receive that official designation.

    “Far beyond Pluto is a region surprisingly rich with planetary bodies. Some are quite small but others have sizes to rival Pluto, and could possibly be much larger,” said David Gerdes, a scientist with the University of Michigan and lead author on a paper appearing in the Astrophysical Journal Letters. “Because these objects are so distant and dim, it’s incredibly difficult to even detect them, let alone study them in any detail. ALMA, however, has unique capabilities that enabled us to learn exciting details about these distant worlds.”

    Currently, DeeDee is about 92 astronomical units (AU) from the Sun. An astronomical unit is the average distance from the Earth to the Sun, or about 150 million kilometers. At this tremendous distance, it takes DeeDee more than 1,100 years to complete one orbit. Light from DeeDee takes nearly 13 hours to reach Earth.

    Gerdes and his team announced the discovery of DeeDee in the fall of 2016. They found it using the 4-meter Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile as part of ongoing observations for the Dark Energy Survey, an optical survey of about 12 percent of the sky that seeks to understand the as-yet mysterious force that is accelerating the expansion of the universe.

    The Dark Energy Survey produces vast troves of astronomical images, which give astronomers the opportunity to also search for distant solar system objects.

    The initial search, which includes nearly 15,000 images, identified more than 1.1 billion candidate objects. The vast majority of these turned out to be background stars and even more distant galaxies. A small fraction, however, were observed to move slowly across the sky over successive observations, the telltale sign of a TNO.

    One such object was identified on 12 separate images. The astronomers informally dubbed it DeeDee, which is short for Distant Dwarf.

    The optical data from the Blanco telescope enabled the astronomers to measure DeeDee’s distance and orbital properties, but they were unable to determine its size or other physical characteristics. It was possible that DeeDee was a relatively small member of our solar system, yet reflective enough to be detected from Earth. Or, it could be uncommonly large and dark, reflecting only a tiny portion of the feeble sunlight that reaches it; both scenarios would produce identical optical data.

    Since ALMA observes the cold, dark universe, it is able to detect the heat – in the form of millimeter-wavelength light – emitted naturally by cold objects in space. The heat signature from a distant solar system object would be directly proportional to its size.

    “We calculated that this object would be incredibly cold, only about 30 degrees Kelvin, just a little above absolute zero,” said Gerdes.

    While the reflected visible light from DeeDee is only about as bright as a candle seen halfway the distance to the moon, ALMA was able to quickly home in on the planetary body’s heat signature and measure its brightness in millimeter-wavelength light.

    This allowed astronomers to determine that it reflects only about 13 percent of the sunlight that hits it. That is about the same reflectivity of the dry dirt found on a baseball infield.

    By comparing these ALMA observations to the earlier optical data, the astronomers had the information necessary to calculate the object’s size. “ALMA picked it up fairly easily,” said Gerdes. “We were then able to resolve the ambiguity we had with the optical data alone.”

    Objects like DeeDee are cosmic leftovers from the formation of the solar system. Their orbits and physical properties reveal important details about the formation of planets, including Earth.

    This discovery is also exciting because it shows that it is possible to detect very distant, slowly moving objects in our own solar system. The researchers note that these same techniques could be used to detect the hypothesized “Planet Nine” that may reside far beyond DeeDee and Eris.

    “There are still new worlds to discover in our own cosmic backyard,” concludes Gerdes. “The solar system is a rich and complicated place.”

    3

    Orbits of objects in our solar system, showing the current location of the planetary body ‘DeeDee’.
    Credit: Alexandra Angelich (NRAO/AUI/NSF)

    Additional information

    This research is presented in a paper titled “Discovery and physical characterization of a large scattered disk object at 92 AU,” appearing in the Astrophysical Journal Letters.

    The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Organisation for Astronomical Research in the Southern Hemisphere (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

    ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

    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

    GBO radio telescope, Green Bank, West Virginia, USA
    Green Bank Observatory radio telescope, Green Bank, West Virginia, USA, formerly supported by NSF, but now on its own
    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 5:13 pm on January 25, 2017 Permalink | Reply
    Tags: ALMA Team Up to Give First Look at Birthplaces of Most Current Stars, , , , NRAO, VLA   

    From NRAO: “VLA, ALMA Team Up to Give First Look at Birthplaces of Most Current Stars” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

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

    1
    Radio/Optical combination images of distant galaxies as seen with NSF’s Very Large Array and NASA’s Hubble Space Telescope. Their distances from Earth are indicated in the top set of images. Below, the same images, without labels. Credit: K. Trisupatsilp, NRAO/AUI/NSF, NASA.

    Astronomers have gotten their first look at exactly where most of today’s stars were born. To do so, they used the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) and the Atacama Large Millimeter/submillimeter Array (ALMA) to look at distant galaxies seen as they were some 10 billion years ago.

    At that time, the Universe was experiencing its peak rate of star formation. Most stars in the present Universe were born then.

    “We knew that galaxies in that era were forming stars prolifically, but we didn’t know what those galaxies looked like, because they are shrouded in so much dust that almost no visible light escapes them,” said Wiphu Rujopakam, of the Kavli Institute for the Physics and Mathematics of the Universe at the University of Tokyo and Chulalongkorn University in Bangkok, who was lead author on the research paper.

    Radio waves, unlike visible light, can get through the dust. However, in order to reveal the details of such distant — and faint — galaxies, the astronomers had to make the most sensitive images ever made with the VLA.

    The new observations, using the VLA and ALMA, have answered longstanding questions about just what mechanisms were responsible for the bulk of star formation in those galaxies. They found that intense star formation in the galaxies they studied most frequently occured throughout the galaxies, as opposed to much smaller regions in present-day galaxies with similar high star-formation rates.

    The astronomers used the VLA and ALMA to study galaxies in the Hubble Ultra Deep Field, a small area of sky observed since 2003 with NASA’s Hubble Space Telescope (HST). The HST made very long exposures of the area to detect galaxies in the far-distant Universe, and numerous observing programs with other telescopes have followed up on the HST work.

    “We used the VLA and ALMA to see deeply into these galaxies, beyond the dust that obscured their innards from Hubble,” said Kristina Nyland, of the National Radio Astronomy Observatory (NRAO). “The VLA showed us where star formation was occurring, and ALMA revealed the cold gas that is the fuel for star formation,” she added.

    “In this study, we made the most sensitive image ever made with the VLA,” said Preshanth Jagannathan, also of NRAO. “If you took your cellphone, which transmits a weak radio signal, and put it at more than twice the distance to Pluto, near the outer edge of the solar system, its signal would be roughly as strong as what we detected from these galaxies,” he added.

    The study of the galaxies was done by an international team of astronomers. Others involved include James Dunlop of the University of Edinburgh and Rob Ivison of the University of Edinburgh and the European Southern Observatory. The researchers reported their findings in the Dec. 1 issue of the Astrophysical Journal.

    ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of South Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ.

    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

    GBO radio telescope, Green Bank, West Virginia, USA
    Green Bank Observatory radio telescope, Green Bank, West Virginia, USA, formerly supported by NSF, but now on its own
    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 4:27 pm on January 25, 2017 Permalink | Reply
    Tags: , , , Milky-Way-Like Galaxies Seen in their Awkward Adolescent Years, , NRAO,   

    From NRAO: “Milky-Way-Like Galaxies Seen in their Awkward Adolescent Years” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    December 20, 2016
    Charles Blue
    NRAO Public Information Officer
    +1 434.296.0314;
    cblue@nrao.edu

    1
    Four Milky-Way-like progenitor galaxies as seen as they would have appeared 9 billion years ago. ALMA observations of carbon monoxide (red) is superimposed on images taken with the Hubble Space Telescope. The carbon monoxide would most likely be suffused throughout the young galaxies. Credit. ALMA (ESO/NAOJ/NRAO) C. Papovich; A. Angelich (NRAO/AUI/NSF); NASA/ESA Hubble Space Telescope

    Spiral galaxies like our own Milky Way were not always the well-ordered, pinwheel-like structures we see in the universe today. Astronomers believe that about 8-10 billion years ago, progenitors of the Milky Way and similar spiral galaxies were smaller, less organized, but amazingly rich in star-forming material; so much so, that they would have been veritable star factories, churning out new stars faster than at any other point in their lifetimes. Now, astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have found evidence to support this view. By studying four very young versions of galaxies like the Milky Way as they were seen approximately 9 billion years ago, the astronomers discovered that each galaxy was incredibly rich in carbon monoxide gas, a well-known tracer of star-forming gas. “We used ALMA to detect adolescent versions of the Milky Way and found that such galaxies do indeed have much higher amounts of molecular gas, which would fuel rapid star formation,” said Casey Papovich, an astronomer at Texas A&M University in College Station and lead author on a paper appearing in Nature Astronomy. “I liken these galaxies to an adolescent human who consumes prodigious amounts of food to fuel their own growth during their teenage years.” Though the relative abundance of star-forming gas is extreme in these galaxies, they are not yet fully formed and rather small compared to the Milky Way as we see it today. The new ALMA data indicate that the vast majority of the mass in these galaxies is in cold molecular gas rather than in stars. These observations, the astronomers note, are helping build a complete picture of how matter in Milky-Way-size galaxies evolved and how our own galaxy formed.

    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

    GBO radio telescope, Green Bank, West Virginia, USA
    Green Bank Observatory radio telescope, Green Bank, West Virginia, USA, formerly supported by NSF, but now on its own
    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 3:11 pm on January 4, 2017 Permalink | Reply
    Tags: , , , , , NRAO   

    From NRAO: “Precise Location, Distance Provide Breakthrough in Study of Fast Radio Bursts” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    4 January 2017

    1
    Visible-light image of host galaxy.
    Credit: Gemini Observatory/AURA/NSF/NRC.

    For the first time, astronomers have pinpointed the location in the sky of a Fast Radio Burst (FRB), allowing them to determine the distance and home galaxy of one of these mysterious pulses of radio waves. The new information rules out several suggested explanations for the source of FRBs.

    “We now know that this particular burst comes from a dwarf galaxy more than three billion light-years from Earth,” said Shami Chatterjee, of Cornell University. “That simple fact is a huge advance in our understanding of these events,” he added. Chatterjee and other astronomers presented their findings to the American Astronomical Society’s meeting in Grapevine, Texas, in the scientific journal Nature, and in companion papers in the Astrophysical Journal Letters.

    Fast Radio Bursts are highly-energetic, but very short-lived (millisecond) bursts of radio waves whose origins have remained a mystery since the first one was discovered in 2007. That year, researchers scouring archived data from Australia’s Parkes Radio Telescope in search of new pulsars found the first known FRB — one that had burst in 2001.

    There now are 18 known FRBs. All were discovered using single-dish radio telescopes that are unable to narrow down the object’s location with enough precision to allow other observatories to identify its host environment or to find it at other wavelengths. Unlike all the others, however, one FRB, discovered in November of 2012 at the Arecibo Observatory in Puerto Rico, has recurred numerous times.

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

    The repeating bursts from this object, named FRB 121102 after the date of the initial burst, allowed astronomers to watch for it using the National Science Foundation’s (NSF) Karl G. Jansky Very Large Array (VLA), a multi-antenna radio telescope system with the resolving power, or ability to see fine detail, needed to precisely determine the object’s location in the sky.

    In 83 hours of observing time over six months in 2016, the VLA detected nine bursts from FRB 121102.

    “For a long time, we came up empty, then got a string of bursts that gave us exactly what we needed,” said Casey Law, of the University of California at Berkeley.

    “The VLA data allowed us to narrow down the position very accurately,” said Sarah Burke-Spolaor, of the National Radio Astronomy Observatory (NRAO) and West Virginia University.

    Using the precise VLA position, researchers used the Gemini North telescope in Hawaii to make a visible-light image that identified a faint dwarf galaxy at the location of the bursts. The Gemini observations also determined that the dwarf galaxy is more than 3 billion light-years from Earth.

    Gemini/North telescope at Mauna Kea, Hawaii, USA
    Gemini/North telescope at Mauna Kea, Hawaii, USA

    “Before we knew the distance to any FRBs, several proposed explanations for their origins said they could be coming from within or near our own Milky Way Galaxy. We now have ruled out those explanations, at least for this FRB,” said Shriharsh Tendulkar, of McGill University in Montreal, Canada.

    In addition to detecting the bright bursts from FRB 121102, the VLA observations also revealed an ongoing, persistent source of weaker radio emission in the same region.

    Next, a team of observers used the multiple radio telescopes of the European VLBI Network (EVN), along with the 1,000-foot-diameter William E. Gordon Telescope of the Arecibo Observatory, and the NSF’s Very Long Baseline Array (VLBA) to determine the object’s position with even greater accuracy.

    European VLBI
    European VLBI

    NRAO VLBA
    NRAO VLBA

    “These ultra high precision observations showed that the bursts and the persistent source must be within 100 light-years of each other,” said Jason Hessels, of the Netherlands Institute for Radio Astronomy and the University of Amsterdam.

    “We think that the bursts and the continuous source are likely to be either the same object or that they are somehow physically associated with each other,” said Benito Marcote, of the Joint Institute for VLBI ERIC, Dwingeloo, Netherlands.

    The top candidates, the astronomers suggested, are a neutron star, possibly a highly-magnetic magnetar, surrounded by either material ejected by a supernova explosion or material ejected by a resulting pulsar, or an active nucleus in the galaxy, with radio emission coming from jets of material emitted from the region surrounding a supermassive black hole.

    “We do have to keep in mind that this FRB is the only one known to repeat, so it may be physically different from the others,” cautioned Bryan Butler of NRAO.

    “Finding the host galaxy of this FRB, and its distance, is a big step forward, but we still have much more to do before we fully understand what these things are,” Chatterjee said.

    “This impressive result shows the power of several telescopes working in concert — first detecting the radio burst and then precisely locating and beginning to characterize the emitting source,” said Phil Puxley, a program director at the National Science Foundation that funds the VLA, VLBA, Gemini and Arecibo observatories. “It will be exciting to collect more data and better understand the nature of these radio bursts.”

    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

    GBO radio telescope, Green Bank, West Virginia, USA
    GBO Radio Observatory telescope, Green Bank, West Virginia, USA, formerly supported by NSF, but now on its own

    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 9:53 am on August 15, 2016 Permalink | Reply
    Tags: , , NRAO, , realfast   

    From NRAO: “Real-time, Commensal Fast Transient Searches at the VLA” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    15 August 2016
    Casey Law (Berkeley), Joe Lazio (JPL), Geoff Bower (ASIAA), Sarah Burke-Spolaor (NRAO), Paul Demorest (NRAO), Bryan Butler (NRAO)

    1

    While the Expanded Very Large Array (VLA) project produced dramatic improvements in sensitivity and frequency coverage, its legacy may be defined by the introduction of powerful and flexible digital signal processing. The power and flexibility of the VLA correlator makes it uniquely capable of doing a broad range of science today and growing to do the science of tomorrow.

    One exciting pursuit for the VLA is the study of “fast radio bursts” (FRBs), a mysterious new class of millisecond radio transient. FRBs seem to come from far outside our galaxy, which would make them unusually luminous and novel probes of the intergalactic medium. As the most sensitive centimeter-wavelength radio interferometer on earth, the VLA will revolutionize this field with its ability to precisely localize sources to identify multi-wavelength counterparts (e.g., a host galaxy). Previously, our group has demonstrated that potential with the introduction of “fast imaging”, a new concept for using the VLA as a high speed camera. Now, we are expanding on that concept with the construction of realfast, a 24 / 7 fast transient survey system at the VLA.

    The core of realfast is a 32-node, Graphics Processing Unit-accelerated compute cluster that will perform real-time transient searches on millisecond timescales as data are received at the VLA, before averaging the data for archive storage. Real-time processing will allow us to rapidly identify transients and trigger recording of data for those brief moments when a transient candidate is detected. Triggered data recording reduces the data flow by orders of magnitude and makes it feasible to observe continuously. We will integrate this system with a duplicate high-speed data stream to turn each VLA observation into a fast transient survey, ultimately encompassing thousands of hours per year.

    Realfast will be supported by a three-year grant from the National Science Foundation Advanced Technologies and Instrumentation program and developed in close collaboration with NRAO staff. Transient alerts and associated data products will be made public. This will make the VLA into a transient survey machine and help connect the public to our rapidly changing understanding of the rapidly changing sky.

    For additional information, visit the realfast website.

    2
    The challenge to using the VLA for millisecond imaging is that it produces roughly 1 TB of data per hour and requires forming many thousands of images per second. This data rate is so large that it cannot be transferred via the internet for data analysis. The computing requirements are so severe that no single computer can manage the search. The question is: how can we manage a TB/hour data stream to find a millisecond transient in hudreds of hours of data?
    Our answer is realfast, a system for real-time fast transient searches at the VLA. Real-time processing is critical, as it allows triggered data recording and opens access to “commensal” observing in conjunction with other VLA observations. realfast is supported by the NSF ATI program starting in late 2016.

    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 radio telescope
    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 9:05 am on August 15, 2016 Permalink | Reply
    Tags: , , NRAO, The Sizes of Lensed Dusty Star-forming Galaxies at High z   

    From NRAO: “The Sizes of Lensed Dusty Star-forming Galaxies at High z” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    15 August 2016
    Aaron Evans

    1
    [a] an example DSFG, where contours of the ALMA 870 micron emission (the background galaxy) are superimposed on an optical HST image. The lens position is marked with the purple diamond. [b] Fully resolved best-fit model image (blue) with caustics (green) superimposed. The inset is a close-up of the source plane. [c] The [C II] deficit versus the far-IR surface brightness. No image credit.

    Gravitational lensing has proven to be a powerful tool for observing high-redshift (z) galaxies that would otherwise be too faint to detect. High-resolution observations of these lensed systems allows for properties such as the lensing factor and the intrinsic size of the background galaxy to be measured. In the August 2016 Astrophysical Journal, Spilker and his collaborators present detailed modeling of 0.5″ resolution, ALMA 870 micron observations of a sample of 47 lensed dusty star-forming galaxies (DSFG) discovered via their South Pole Telescope submillimeter survey (see Figure panels a and b).

    South Pole Telescope SPTPOL
    South Pole Telescope

    They find a median lensing magnification of 5.5 for the sample, and an intrinsic background galaxy size distribution comparable to the distribution of un-lensed high-z DSFGs. They also find that these lensed systems follow the [CII] 158 micron-to-far IR luminosity ratio versus far-IR surface brightness relation observed for low-redshift IR galaxies (see panel c), where the [CII] “deficit” is correlated with increasing surface brightness (no deficit is observed for normal star-forming galaxies). While the nature of the observed deficit in this major ISM coolant is not well understood, it is clearly correlated with the compactness of the active regions in these extreme star-forming galaxies relative to normal star-forming galaxies.

    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 radio telescope
    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 6:03 pm on June 2, 2016 Permalink | Reply
    Tags: , , New Observational Distance Record Promises Important Tool for Studying Galaxies, NRAO,   

    From NRAO: “New Observational Distance Record Promises Important Tool for Studying Galaxies” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

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

    1
    Radio-optical image of the galaxy J100054. Background image is visible-light as seen with Hubble Space Telescope. Orange shows radio emission from atomic hydrogen gas surrounding the galaxy. CREDIT: Fernandez et al., Bill Saxton, NRAO/AUI/NSF; Koekemoer et al., Massey et al., NASA.

    Astronomers have used new capabilities of the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) to open a whole new realm of research into how galaxies evolve and interact with their surroundings over cosmic time. They detected the faint radio emission from atomic hydrogen, the most abundant element in the Universe, in a galaxy nearly 5 billion light-years from Earth.

    “This almost doubles the distance record for this type of observation, and promises key new insights into how galaxies draw in the gas, process it, and lose it as they evolve,” said Ximena Fernandez, of Rutgers University. “As we look farther out in distance, we’re looking farther back in time, so this new capability allows us to gain previously unobtainable information about how galaxies develop,” she added.

    The scientists detected the radio “fingerprint” of hydrogen in a galaxy called COSMOS J100054. The discovery came from the first 178 hours of observation in a program called the COSMOS HI Large Extragalactic Survey, or CHILES, led by Jacqueline van Gorkom of Columbia University. The CHILES project eventually will use more than 1,000 hours of VLA observing time. The detection was made possible by the improved capabilities of the VLA provided by a 10-year upgrade project completed in 2012.

    “The new electronic systems in the upgraded VLA were essential to this work. Without the upgrade, this discovery would have been impossible. This detection is the first of what we believe will be many more to come, making an important contribution to our understanding of how galaxies evolve,” said Emmanuel Momjian, of the National Radio Astronomy Observatory.

    Hydrogen gas is the raw material for making stars. Throughout their lives, galaxies draw in the gas, which eventually is incorporated into stars. In furious bursts of star formation, stellar winds and supernova explosions can blow gas out of the galaxy and rob it of the material needed for further star formation.

    In order to understand how these processes develop, astronomers need images of the gas in and near galaxies of different ages. Until now, technical limitations of radio telescopes prevented them from detecting atomic hydrogen emission at the distances needed to see the gas in galaxies distant enough to provide the required “lookback time.” The CHILES project will achieve this to distances out to about 6 billion light-years.

    COSMOS J100054 is in a region of sky extensively studied with multiple telescopes as part of an international project called the Cosmological Evolution Survey (COSMOS). Data from that survey allowed the scientists to glean additional information about the galaxy. In addition, Hansung Gim of the University of Massachusetts, Amherst, used the Large Millimeter Telescope in Mexico to detect Carbon Monoxide (CO) in the galaxy.

    Large Millimeter Telescope Alfonso Serrano
    Large Millimeter Telescope Alfonso Serrano, Mexico

    The CO detection gave the researchers key information about gas in the galaxy that is composed of molecules, rather than of individual atoms. Molecular gas is considered a necessary precursor to star formation.

    The scientists found that COSMOS J100054 is a massive, barred spiral galaxy that may be interacting with a small neighbor galaxy. With an amount of hydrogen nearly 100 billion times the mass of the Sun, the galaxy is forming the equivalent of about 85 suns every year.

    “This is the first time we have been able to observe both the emission from atomic hydrogen and from carbon monoxide in a galaxy that is beyond our local Universe,” Gim said. “Now that we have this capability, we soon will be able to start filling in gaps in our knowledge about the properties of galaxies at specific ages. This is an important development,” he added.

    The research was the work of an international team of astronomers from North America, South America, Europe, Asia and Australia. The scientists are reporting their results* in the Astrophysical Journal Letters.

    *Science paper:
    HIGHEST REDSHIFT IMAGE OF NEUTRAL HYDROGEN IN EMISSION: A CHILES DETECTION OF A STARBURSTING GALAXY AT z = 0.376

    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 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.

     
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