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  • richardmitnick 6:39 am on July 23, 2016 Permalink | Reply
    Tags: , Radio Astronomy, , Statement from the Board of Directors of SKA Organisation on the outcome of the UK’s EU referendum   

    From SKA: “Statement from the Board of Directors of SKA Organisation on the outcome of the UK’s EU referendum” 

    SKA Square Kilometer Array

    SKA

    The Board of Directors of the Square Kilometre Array (SKA) Organisation recently met at the SKA Headquarters at Jodrell Bank near Manchester in the UK for its 21st Board Meeting. This is the first time the Board has met since the result of the UK’s EU referendum held a few weeks ago and the consequent decision to leave the EU.

    Dr Adam Baker from the Science and Research Directorate of the UK Department for Business, Energy and Industrial Strategy (BEIS) reaffirmed the strong commitment of the country to the SKA project stating that “with respect to the Square Kilometre Array itself, the UK’s position has not changed. We are still deeply committed to the SKA and its success. The Minister for Universities and Science, Jo Johnson re-iterated the UK’s support for world class research and innovation at a speech to the Wellcome Trust on 30th June. This included specific reference to the SKA.”

    All SKA members’ representatives in the Board took note of the positive statement from the UK, keeping the project on the right track ahead of the construction in 2018 in particular the pursuing of international negotiations to establish the SKA as an Inter-Governmental Organisation or IGO –similar to CERN or ITER.

    All members of the Board, the Director-General of SKA Organisation and the Chair of the Board also took this opportunity to express their pride in the international nature of the SKA project and emphasised the essential contribution of the highly qualified personnel from over 14 different nationalities working at the SKA Headquarters in the UK as well as around the world to deliver the project.

    “The recruitment of talent from around the world is what makes a project such as SKA possible and all members of the Board remain fully committed to ensuring the SKA project can attract and recruit the best and most qualified staff regardless of their origin,” concluded Giovanni Bignami, Chair of the SKA Board.

    See the full article here .

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    About SKA

    The Square Kilometre Array will be the world’s largest and most sensitive radio telescope. The total collecting area will be approximately one square kilometre giving 50 times the sensitivity, and 10 000 times the survey speed, of the best current-day telescopes. The SKA will be built in Southern Africa and in Australia. Thousands of receptors will extend to distances of 3 000 km from the central regions. The SKA will address fundamental unanswered questions about our Universe including how the first stars and galaxies formed after the Big Bang, how dark energy is accelerating the expansion of the Universe, the role of magnetism in the cosmos, the nature of gravity, and the search for life beyond Earth. Construction of phase one of the SKA is scheduled to start in 2016. The SKA Organisation, with its headquarters at Jodrell Bank Observatory, near Manchester, UK, was established in December 2011 as a not-for-profit company in order to formalise relationships between the international partners and centralise the leadership of the project.

    The Square Kilometre Array (SKA) project is an international effort to build the world’s largest radio telescope, led by SKA Organisation. The SKA will conduct transformational science to improve our understanding of the Universe and the laws of fundamental physics, monitoring the sky in unprecedented detail and mapping it hundreds of times faster than any current facility.

    Already supported by 10 member countries – Australia, Canada, China, India, Italy, New Zealand, South Africa, Sweden, The Netherlands and the United Kingdom – SKA Organisation has brought together some of the world’s finest scientists, engineers and policy makers and more than 100 companies and research institutions across 20 countries in the design and development of the telescope. Construction of the SKA is set to start in 2018, with early science observations in 2020.

     
  • richardmitnick 8:26 am on July 17, 2016 Permalink | Reply
    Tags: , First Light, Radio Astronomy,   

    From SKA: “MeerKAT joins the ranks of the world’s great scientific instruments through its First Light image” 

    SKA Square Kilometer Array

    SKA

    16 July 2016
    Lorenzo Raynard, SKA SA Communication Manager
    lorenzo@ska.ac.za
    (+27) 71 454 0658

    1
    IMAGE 1: MeerKAT First Light image. Each white dot represents the intensity of radio waves recorded with 16 dishes of the MeerKAT telescope in the Karoo (when completed, MeerKAT will consist of 64 dishes and associated systems). More than 1300 individual objects – galaxies in the distant universe – are seen in this image.

    The MeerKAT First Light image of the sky, released today by Minister of Science and Technology, Naledi Pandor, shows unambiguously that MeerKAT is already the best radio telescope of its kind in the Southern Hemisphere. Array Release 1 (AR1) being celebrated today provides 16 of an eventual 64 dishes integrated into a working telescope array. It is the first significant scientific milestone achieved by MeerKAT, the radio telescope under construction in the Karoo that will eventually be integrated into the Square Kilometre Array (SKA).

    SKA Meerkat telescope, South African design
    SKA Meerkat telescope, South African design

    3
    When fully up and running in the 2020s, the SKA will comprise a forest of 3,000 dishes spread over an area of a square kilometre (0.4 square miles) across remote terrain around several countries. phys.org

    In a small patch of sky covering less than 0.01 percent of the entire celestial sphere, the MeerKAT First Light image shows more than 1300 galaxies in the distant Universe, compared to 70 known in this location prior to MeerKAT. “Based on the results being shown today, we are confident that after all 64 dishes are in place, MeerKAT will be the world’s leading telescope of its kind until the advent of SKA,” according to Professor Justin Jonas, SKA South Africa Chief Technologist.

    MeerKAT will consist of 64 receptors, each comprising a 13.5-metre diametre dish antenna, cryogenic coolers, receivers, digitiser, and other electronics. The commissioning of MeerKAT is done in phases to allow for verification of the system, early resolution of any technical issues, and initial science exploitation. Early science can be done with parts of the array as they are commissioned, even as construction continues. AR1 consists of 16 receptors, AR2 of 32 and AR3 of 64, expected to be in place by late 2017.

    Dr Rob Adam, Project Director of SKA South Africa, says: “The launch of MeerKAT AR1 and its first results is a significant milestone for South Africa. Through MeerKAT, South Africa is playing a key role in the design and development of technology for the SKA. The South African team of more than 200 young scientists, engineers and technicians, in collaboration with industry, local and foreign universities and institutions, has developed the technologies and systems for MeerKAT. These include cutting edge telescope antennas and receivers, signal processing, timing, telescope management, computing and data storage systems, and algorithms for data processing.”

    2
    IMAGE 2: Montage of MeerKAT First Light radio image and four zoomed-in insets. The two panels to the right show distant galaxies with massive black holes at their centers. At lower left is a galaxy approximately 200 million light years away, where hydrogen gas is being used up to form stars in large numbers.

    3
    IMAGE 3: View showing 10% of the full MeerKAT First Light radio image. More than 200 astronomical radio sources (white dots) are visible in this image, where prior to MeerKAT only five were known (indicated by violet circles). This image spans about the area of the Earth’s moon.

    In May 2016, more than 150 researchers and students, two-thirds from South Africa, met in Stellenbosch to discuss and update the MeerKAT science programme. This will consist of already approved “large survey projects”, plus “open time” available for new projects. An engineering test image, produced with only 4 dishes, was made available just before that meeting.

    “The scientists gathered at the May meeting were impressed to see what 4 MeerKAT dishes could do,” says Dr Fernando Camilo, SKA South Africa Chief Scientist. “They will be astonished at today’s exceptionally beautiful images, which demonstrate that MeerKAT has joined the big leagues of world radio astronomy”.

    Pandor today released the MeerKAT First Light image from the telescope site in the Northern Cape. She was accompanied by Ministers and Deputy Ministers from the Presidential Infrastructure Coordination Committee (PICC), as well as other senior officials.

    Minister Pandor says: “South Africa has already demonstrated its excellent science and engineering skills by designing and building MeerKAT. This telescope, which is predominantly a locally designed and built instrument, shows the world that South Africa can compete in international research, engineering, technology and science. Government is proud of our scientists and engineers for pioneering a radio telescope that will lead to groundbreaking research.”

    MeerKAT is a precursor to the Square Kilometre Array (SKA) and follows the KAT-7 telescope which was an engineering test-bed for MeerKAT. MeerKAT is funded by the South African Government and is a South African designed telescope with 75% of its value sourced locally. MeerKAT will be an integral part of SKA Phase 1. An important aspect of the SKA site decision in 2012 was that MeerKAT would be part of the sensitive SKA Phase 1 array, which will be the most sensitive radio telescope in the world. Upon completion at the end of 2017, MeerKAT will consist of 64 dishes and associated instrumentation. SKA1 MID will include an additional 133 dishes, bringing the total number for SKA1 MID to 197.

    See the full article here .

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    SKA ASKAP Pathefinder Telescope

    SKA Meerkat telescope
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    SKA Murchison Widefield Array
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    About SKA

    The Square Kilometre Array will be the world’s largest and most sensitive radio telescope. The total collecting area will be approximately one square kilometre giving 50 times the sensitivity, and 10 000 times the survey speed, of the best current-day telescopes. The SKA will be built in Southern Africa and in Australia. Thousands of receptors will extend to distances of 3 000 km from the central regions. The SKA will address fundamental unanswered questions about our Universe including how the first stars and galaxies formed after the Big Bang, how dark energy is accelerating the expansion of the Universe, the role of magnetism in the cosmos, the nature of gravity, and the search for life beyond Earth. Construction of phase one of the SKA is scheduled to start in 2016. The SKA Organisation, with its headquarters at Jodrell Bank Observatory, near Manchester, UK, was established in December 2011 as a not-for-profit company in order to formalise relationships between the international partners and centralise the leadership of the project.

    The Square Kilometre Array (SKA) project is an international effort to build the world’s largest radio telescope, led by SKA Organisation. The SKA will conduct transformational science to improve our understanding of the Universe and the laws of fundamental physics, monitoring the sky in unprecedented detail and mapping it hundreds of times faster than any current facility.

    Already supported by 10 member countries – Australia, Canada, China, India, Italy, New Zealand, South Africa, Sweden, The Netherlands and the United Kingdom – SKA Organisation has brought together some of the world’s finest scientists, engineers and policy makers and more than 100 companies and research institutions across 20 countries in the design and development of the telescope. Construction of the SKA is set to start in 2018, with early science observations in 2020.

     
  • richardmitnick 2:12 pm on July 13, 2016 Permalink | Reply
    Tags: , ALMA Observes First Protoplanetary Water Snow Line Thanks to Stellar Outburst, , , , Radio Astronomy   

    From ALMA: “ALMA Observes First Protoplanetary Water Snow Line Thanks to Stellar Outburst” 

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

    13 July 2016
    Lucas Cieza
    Universidad Diego Portales
    Santiago, Chile
    Tel: +56 22 676 8154
    Cell: +56 95 000 6541
    Email: lucas.cieza@mail.udp.cl

    Nicolás Lira T.
    Education and Public Outreach 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

    Richard Hook
    Public Information Officer, ESO

    Garching bei München, Germany

    Tel: +49 89 3200 6655

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

    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

    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 impression of the water snowline around the young star V883 Orionis, as detected with ALMA. Credit: A. Angelich (NRAO/AUI/NSF)/ALMA (ESO/NAOJ/NRAO).

    New observations with the Atacama Large Millimeter/submillimeter Array (ALMA) have produced the first image of a water snow line within a protoplanetary disk. This line marks where the temperature in the disk surrounding a young star drops sufficiently low for snow to form. A dramatic increase in the brightness of the young star V883 Orionis flash heated the inner portion of the disk, pushing the water snow line out to a far greater distance than is normal for a protostar, and making it possible to observe it for the first time. The results will be published in the journal Nature on July 14, 2016.

    2
    Image of the planet-forming disc around the young star V883 Orionis was obtained by ALMA in long-baseline mode. This star is currently in outburst, which has pushed the water snow line further from the star and allowed it to be detected for the first time. The dark ring midway through the disc is the water snowline, the point from the star where the temperature and pressure dip low enough for water ice to form. Credit: ALMA (ESO/NAOJ/NRAO)/L. Cieza.

    Young stars are often surrounded by dense, rotating disks of gas and dust, known as protoplanetary disks, from which planets are born. Snow lines are the regions in those disks where the temperature reaches the sublimation point for most of the volatile molecules. In the inner disk regions, inside water snow lines, water is vaporized, while outside these lines, in the outer disk, water is found frozen in the form of snow. These lines are so important that they define the basic architecture of planetary systems like our own [1] and are usually located for a typical solar-type star at around 3 au from the star [2].

    However, the recent ALMA observations, to be published in Nature, show that the water snow line in V883 Orionis is currently at more than 40 au of the central star (corresponding to Neptune’s orbit in our system), greatly facilitating its detection [3]. This star is only thirty percent more massive than the Sun, but its luminosity is 400 times brighter as it’s currently experiencing what is known as a FU Ori outburst, a sudden increase in temperature and luminosity due to large amounts of material being transferred from the disk to the star [4]. This explains the displaced location of its water snow line: the disk has been flash-heated by the stellar outburst.

    Lead author Lucas Cieza explains: “The ALMA observations came as a surprise to us. Our observations were designed to look for disk fragmentation leading to planet formation. We saw none of that; instead, we found what looks like a ring at 40 au. This illustrates well the transformational power of ALMA, which delivers exciting results even if they are not the ones we were looking for.”

    The discovery that these outbursts may blast the water snow line to about 10 times its typical radius is very significant for the development of good planetary formation models. Such outbursts are believed to be a stage in the evolution of most planetary systems, so this may be the first observation of a common occurrence. In that case, this observation from ALMA could contribute significantly to a better understanding of how planets form and evolve throughout the Universe.

    3
    This illustration shows how the outburst of the young star V883 Orionis has displaced the water snowline much further out from the star, and rendered it detectable with ALMA. Credit: ALMA (ESO/NAOJ/NRAO)/L. Cieza.

    4
    This image of the planet-forming disc around the young star V883 Orionis was obtained by ALMA in long-baseline mode. This star is currently in outburst, which has pushed the water snow line further from the star and allowed it to be detected for the first time. The dark ring midway through the disc is the water snowline, the point from the star where the temperature and pressure dip low enough for water ice to form. Credit: ALMA (ESO/NAOJ/NRAO)/L. Cieza.

    Notes

    [1] In the solar nebula – which gave birth to our Solar System – this line was between the orbits of Mars and Jupiter during the formation of the Solar System, hence the rocky planets Mercury, Venus, Earth and Mars formed within the line, and the gaseous planets Jupiter, Saturn, Uranus and Neptune formed outside.

    [2] 1 au, or one astronomical unit, is the mean distance between the Earth and the Sun, around 149.6 million kilometers. This unit is typically used to describe distances measured within the Solar System and planetary systems around other stars.

    [3] Resolution is the ability to discern that objects are separate. To the human eye, several bright torches at a distance would seem like a single glowing spot, and only at closer quarters would each torch be distinguishable. The same principle applies to telescopes, and these new observations have exploited the exquisite resolution of ALMA in its long baseline modes. The resolution of ALMA at the distance of V883 Orionis is about 12 au — enough to resolve the water snow line at 40 au in this outbursting system, but not for a typical young star.

    [4] Stars are believed to acquire most of their mass during these short but intense accretion events.

    Additional information

    These observation results were published in a paper entitled “Imaging the water snow-line during a protostellar outburst” to appear in the journal Nature on 14 July, 2016.

    The research team is composed of Lucas A. Cieza [1,2], Simón Casassus [2,3], John Tobin [4], Steven Bos [4], Jonathan P. Williams [5], Sebastián Pérez [2,3], Zhaohuan Zhu [6], Claudio Cáceres [2,7], Héctor Cánovas [2,7], Michael M. Dunham [8], Antonio Hales [9], José L. Prieto [1], David A. Príncipe [1,2], Matthias R. Schreiber [2,7], Dary Ruiz-Rodríguez [10] and Alice Zurlo [1,2,3].

    [1] Núcleo de Astronomía, Facultad de Ingeniería, Universidad Diego Portales, Santiago, Chile.

    [2] Millenium Nucleus “Protoplanetary Disks in ALMA Early Science”, Santiago, Chile.

    [3] Departamento de Astronomía, Universidad de Chile, Santiago, Chile.

    [4] Leiden Observatory, Leiden University, Leiden, The Netherlands.

    [5] Institute for Astronomy, University of Hawaii at Manoa, Honolulu, USA.

    [6] Department of Astrophysical Sciences, Princeton University, Princeton, USA.

    [7] Departamento de Física y Astronomía, Universidad de Valparaíso, Valparaíso, Chile.

    [8] Harvard-Smithsonian Center for Astrophysics, Cambridge, USA.


    [9] Joint ALMA Observatory, Santiago, Chile.

    [10] Australian National University, Mount Stromlo Observatory, Canberra, Australia.

    See the full article here .

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    The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

    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.

    NRAO Small

    ESO 50

    NAOJ

     
  • richardmitnick 10:00 am on July 9, 2016 Permalink | Reply
    Tags: , ALMA finds a swirling cool jet that reveals a growing supermassive black hole, , , ONSALA, Radio Astronomy   

    From ONSALA: “ALMA finds a swirling cool jet that reveals a growing supermassive black hole” 

    1

    ONSALA

    7.4.16
    No writer credit found

    1
    1.Alma’s close-up view of the centre of galaxy NGC 1377 (upper left) reveals a swirling jet. In this colour-coded image, reddish gas clouds are moving away from us, bluish clouds towards us, relative to the galaxy’s centre. The Alma image shows light with wavelength around one millimetre from molecules of carbon monoxide (CO). A cartoon view (lower right) shows how these clouds are moving, this time seen from the side. ​CTIO/H. Roussel et al./ESO (left panel); Alma/ESO/NRAO/S. Aalto (top right panel); S. Aalto (lower right panel)

    A Chalmers-led team of astronomers have used the Alma telescope to make the surprising discovery of a jet of cool, dense gas in the centre of a galaxy located 70 million light years from Earth. The jet, with its unusual, swirling structure, gives new clues to a long-standing astronomical mystery – how supermassive black holes grow.

    A team of astronomers led by Susanne Aalto, professor of radio astronomy at Chalmers, has used the Alma telescope (Atacama Large Millimeter/submillimeter Array) to observe a remarkable structure in the centre of the galaxy NGC 1377, located 70 million light years from Earth in the constellation Eridanus (the River).

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

    The results are presented in a paper published in the June 2016 issue of the journal Astronomy and Astrophysics.

    “We were curious about this galaxy because of its bright, dust-enshrouded centre. What we weren’t expecting was this: a long, narrow jet streaming out from the galaxy nucleus”, says Susanne Aalto.

    2
    2. Alma’s close-up view of the centre of galaxy NGC 1377 reveals a swirling jet. In this colour-coded image, reddish gas clouds are moving away from us, bluish clouds towards us, relative to the galaxy’s centre. The image shows light with wavelength around one millimetre from molecules of carbon monoxide (CO).
    Image credit: ALMA/ESO/NRAO/S. Aalto & F. Costagliola

    The observations with Alma reveal a jet which is 500 light years long and less than 60 light years across, travelling at speeds of at least 800 000 kilometres per hour (500 000 miles per hour).

    Most galaxies have a supermassive black hole in their centres; these black holes can have masses of between a few million to a billion solar masses. How they grew to be so massive is a long-standing mystery for scientists.

    A black hole’s presence can be seen indirectly by telescopes when matter is falling into it – a process which astronomers call “accretion”. Jets of fast-moving material are typical signatures that a black hole is growing by accreting matter. The jet in NGC 1377 reveals the presence of a supermassive black hole. But it has even more to tell us, explains Francesco Costagliola (Chalmers and ORA-INAF, Italy), co-author on the paper.

    3
    3. This cartoon view shows how the clouds of material that make up the jet are moving outward from the central black hole, this time seen from the side. Red colours show clouds that are moving away from us, and blue colours show clouds that are moving towards us, relative to the black hole in the galaxy’s centre.
    Image credit: S. Aalto

    “The jets we usually see emerging from galaxy nuclei are very narrow tubes of hot plasma. This jet is very different. Instead it’s extremely cool, and its light comes from dense gas composed of molecules”, he says.

    The jet has ejected molecular gas equivalent to two million times the mass of the Sun over a period of only around half a million years – a very short time in the life of a galaxy. During this short and dramatic phase in the galaxy’s evolution, its central, supermassive black hole must have grown fast.

    “Black holes that cause powerful narrow jets can grow slowly by accreting hot plasma. The black hole in NGC1377, on the other hand, is on a diet of cold gas and dust, and can therefore grow – at least for now – at a much faster rate”, explains team member Jay Gallagher (University of Wisconsin-Madison).

    The motion of the gas in the jet also surprised the astronomers. The measurements with Alma are consistent with a jet that is precessing – swirling outwards like water from a garden sprinkler.

    “The jet’s unusual swirling could be due to an uneven flow of gas towards the central black hole. Another possibility is that the galaxy’s centre contains two supermassive black holes in orbit around each other”, says Sebastien Muller, Chalmers, also a member of the team.

    The discovery of the remarkable cool, swirling jet from the centre of this galaxy would have been impossible without Alma, concludes Susanne Aalto.

    “Alma’s unique ability to detect and measure cold gas is revolutionising our understanding of galaxies and their central black holes. In NGC 1377 we’re witnessing a transient stage in a galaxy’s evolution which will help us understand the most rapid and important growth phases of supermassive black holes, and the life cycle of galaxies in the universe”, she says.

    More about the research

    This research is presented in the article A precessing molecular jet signaling an obscured, growing supermassive black hole in NGC 1377?, published in the June 2016 issue of Astronomy and Astrophysics (http://dx.doi.org/10.1051/0004-6361/201527664).

    The team is composed of Susanne Aalto (Chalmers), Francesco Costagliola (Chalmers and ORA-INAF, Italy), Sebastien Muller (Chalmers), K, Sakamoto (Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan), Jay S. Gallagher (Department of Astronomy, University of Wisconsin-Madison), K. Dasyra (National and Kapodistrian​ University of Athens, Greece), K. Wada (Kagoshima University, Japan), F. Combes (Paris Observatory, France), S. Garcia-Burillo (Observatorio Astronomico Nacional (OAN)-Observatorio de Madrid, Spain), L. E. Kristensen (Harvard-Smithsonian Center for Astrophysics, USA), S. Martin (European Southern Observatory, Joint Alma Observatory and IRAM, France), P. van der Werf (Leiden Observatory, Netherlands), A. S. Evans (University of Virginia and Virginia and National Radio Astronomy Observatory, USA) and J. Kotilainen (Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Finland).

    See the full article here .

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    Onsala 20 meter telescope exterior Sweden
    Onsala 20 meter telescope Sweden

    Onsala Space Observatory (OSO), the Swedish National Facility for Radio Astronomy, provides scientists with equipment to study the Earth and the rest of the Universe. We operate several radio telescopes in Onsala, 45 km south of Göteborg, and take part in international projects. The observatory is a geodetic fundamental station. Examples of facilities and activities:

    The 20 and 25 m telescopes in Onsala: Studies of the birth and death of stars, and of molecules in the Milky Way and other galaxies.
    The LOFAR station in Onsala: One part of an international network of antennas for studies of, e.g., the early history of the Universe.
    VLBI: Telescopes in different countries are linked together for better resolution (“sharper images”) and for measurements of the Earth.
    SKA: Developing technology for the world’s largest radio telescope.
    APEX: Radio telescope in Chile for sub-millimetre waves. Research about everything from planets to the structure of the Universe.
    ALMA: Using and developing the Atacama Large Millimeter/submillimeter Array in Chile.
    Space geodesy: Radio telescopes (VLBI), satellites (e.g., GPS), gravimeters and tide gauges are used to measure, e.g., Earth’s rotation, movements in Earth’s crust, sea level, and water vapour in the atmosphere.
    Time keeping: Two hydrogen maser clocks and one cesium clock contribute to establishing the official Swedish time and international time.
    SALSA: Small radio telescopes in Onsala for educational purposes.
    Receiver development: Laboratories for development of sensitive radio receivers.

    Onsala Space Observatory is hosted by Department of Earth and Space Sciences at Chalmers University of Technology, and is operated on behalf of the Swedish Research Council. There are particularly strong links to the Department’s research groups in Advanced receiver development, Radio astronomy and astrophysics, Space geodesy and geodynamics, and Global environmental measurements and modelling.

    The observatory was founded in 1949 by professor Olof Rydbeck.

     
  • richardmitnick 6:59 am on July 6, 2016 Permalink | Reply
    Tags: , , , , Radio Astronomy   

    From RAS: “Earth-size telescope tracks the aftermath of a star being swallowed by a supermassive black hole” 

    Royal Astronomical Society

    Royal Astronomical Society

    05 July 2016
    Media contact

    Robert Cumming
    Communications Officer
    Onsala Space Observatory
    Chalmers University of Technology
    Sweden
    Tel: +46 70 493 3114 or +46 (0)31 772 5500
    robert.cumming@chalmers.se

    Science contact

    Jun Yang
    Onsala Space Observatory
    Chalmers University of Technology
    Sweden
    Tel: +46 (0)31 7725531
    jun.yang@chalmers.se

    Radio astronomers have used a radio telescope network the size of the Earth to zoom in on a unique phenomenon in a distant galaxy: a jet activated by a star being consumed by a supermassive black hole. The record-sharp observations reveal a compact and surprisingly slowly moving source of radio waves, with details published in a paper in the journal Monthly Notices of the Royal Astronomical Society. The results will also be presented at the European Week of Astronomy and Space Science in Athens, Greece, on Friday 8 July 2016.

    1
    This artist’s impression shows the remains of a star that came too close to a supermassive black hole. Extremely sharp observations of the event Swift J1644+57 with the radio telescope network EVN (European VLBI Network) have revealed a remarkably compact jet, shown here in yellow. Image credit: ESA/S. Komossa/Beabudai Design.

    The international team, led by Jun Yang (Onsala Space Observatory, Chalmers University of Technology, Sweden), studied the new-born jet in a source known as Swift J1644+57 with the European VLBI Network (EVN), an Earth-size radio telescope array.

    European VLBI
    European VLBI

    When a star moves close to a supermassive black hole it can be disrupted violently. About half of the gas in the star is drawn towards the black hole and forms a disc around it. During this process, large amounts of gravitational energy are converted into electromagnetic radiation, creating a bright source visible at many different wavelengths.

    One dramatic consequence is that some of the star’s material, stripped from the star and collected around the black hole, can be ejected in extremely narrow beams of particles at speeds approaching the speed of light. These so-called relativistic jets produce strong emission at radio wavelengths.

    The first known tidal disruption event that formed a relativistic jet was discovered in 2011 by the NASA satellite Swift. Initially identified by a bright flare in X-rays, the event was given the name Swift J1644+57. The source was traced to a distant galaxy, so far away that its light took around 3.9 billion years to reach Earth.

    Jun Yang and his colleagues used the technique of very long baseline interferometry (VLBI), where a network of detectors separated by thousands of kilometres are combined into a single observatory, to make extremely high-precision measurements of the jet from Swift J1644+57.

    2
    Three years of extremely precise EVN measurements of the jet from Swift J1644+5734 show a very compact source with no signs of motion. Lower panel: false colour contour image of the jet (the ellipse in the lower left corner shows the size of an unresolved source). Upper panel: position measurement with dates. One microarcsecond is one 3 600 000 000th part of a degree. Image credit: EVN/JIVE/J. Yang.

    “Using the EVN telescope network we were able to measure the jet’s position to a precision of 10 microarcseconds. That corresponds to the angular extent of a 2-Euro coin on the Moon as seen from Earth. These are some of the sharpest measurements ever made by radio telescopes”, says Jun Yang.

    Thanks to the amazing precision possible with the network of radio telescopes, the scientists were able to search for signs of motion in the jet, despite its huge distance.

    “We looked for motion close to the light speed in the jet, so-called superluminal motion. Over our three years of observations such movement should have been clearly detectable. But our images reveal instead very compact and steady emission – there is no apparent motion”, continues Jun Yang.

    The results give important insights into what happens when a star is destroyed by a supermassive black hole, but also how newly launched jets behave in a pristine environment. Zsolt Paragi, Head of User Support at the Joint Institute for VLBI ERIC (JIVE) in Dwingeloo, Netherlands, and member of the team, explains why the jet appears to be so compact and stationary.

    “Newly formed relativistic ejecta decelerate quickly as they interact with the interstellar medium in the galaxy. Besides, earlier studies suggest we may be seeing the jet at a very small angle. That could contribute to the apparent compactness”, he says.

    The record-sharp and extremely sensitive observations would not have been possible without the full power of the many radio telescopes of different sizes which together make up the EVN, explains Tao An from the Shanghai Astronomical Observatory, P.R. China.

    “While the largest radio telescopes in the network contribute to the great sensitivity, the larger field of view provided by telescopes like the 25-m radio telescopes in Sheshan and Nanshan (China), and in Onsala (Sweden) played a crucial role in the investigation, allowing us to simultaneously observe Swift J1644+57 and a faint reference source,” he says.

    Swift J1644+57 is one of the first tidal disruption events to be studied in detail, and it won’t be the last.

    “Observations with the next generation of radio telescopes will tell us more about what actually happens when a star is eaten by a black hole – and how powerful jets form and evolve right next to black holes”, explains Stefanie Komossa, astronomer at the Max Planck Institute for Radio Astronomy in Bonn, Germany.

    “In the future, new, giant radio telescopes like FAST (Five hundred meter Aperture Spherical Telescope) and SKA (Square Kilometre Array) will allow us to make even more detailed observations of these extreme and exciting events,” concludes Jun Yang.

    See the full article here .

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  • richardmitnick 5:38 am on July 2, 2016 Permalink | Reply
    Tags: , ALMA discovers dew drops surrounding dusty spider’s web, , , , Radio Astronomy   

    From RAS: “ALMA discovers dew drops surrounding dusty spider’s web” 

    Royal Astronomical Society

    Royal Astronomical Society

    01 July 2016
    Media contacts

    Dr Robert Massey
    Royal Astronomical Society
    Mob: +44 (0)7802 877 699
    rm@ras.org.uk

    Ms Anita Heward
    Royal Astronomical Society
    Mob: +44 (0)7756 034 243
    anitaheward@btinternet.com

    Science contacts

    Dr Bitten Gullberg
    Centre for Extragalactic Astronomy
    Durham University
    bitten.gullberg@durham.ac.uk

    1`
    The Spiderweb Galaxy as seen by the Hubble Space Telescope (optical) in red, the Very Large Array (radio) in green and the Atacama Large Millimeter/submillimeter Array (sub-millimetre) in blue. The red colour shows where the stars are located within this system of galaxies. The radio jet is shown in green, and the position of the dust and water are seen in blue. The water is located to the left and right of the central galaxy. The water to the right is at the position where the radio jet bends down wards. The dust is also seen in blue. The dust is located at the central galaxy and in smaller companion galaxies in its surroundings. Credit: NASA/ESA/HST/STScI/NRAO/ESO/

    Astronomers have spotted glowing droplets of condensed water in the distant Spiderweb Galaxy – but not where they expected to find them. Detections with the Atacama Large Millimeter/submillimeter Array (ALMA) show that the water is located far out in the galaxy and therefore cannot be associated with central, dusty, star-forming regions, as previously thought.

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

    The results will be presented at the National Astronomy Meeting 2016 in Nottingham by Dr Bitten Gullberg on Friday 1st July.

    “Observations of light emitted by water and by dust often go hand-in-hand. We usually interpret them as an insight into star-forming regions, with the illumination from young stars warming dust particles and water molecules until they start to glow. Now, thanks to the power of ALMA, we can — for the first time — separate out the emissions from the dust and water populations, and pinpoint their exact origins in the galaxy. The results are quite unexpected in that we’ve found that the water is located nowhere near the dusty stellar nurseries,” explained Dr Gullberg, of the Centre for Extragalactic Astronomy, Durham University, UK.

    The Spiderweb Galaxy is one of the most massive galaxies known. It lies 10 billion light-years away and is made up of dozens of star-forming galaxies in the process of merging together. The ALMA observations show that the light from the dust originates in the Spiderweb Galaxy itself. However, the light from the water is concentrated in two regions far to the east and west of the galaxy core.

    Gullberg and her colleagues believe that the explanation lies with powerful jets of radio waves that are ejected from a supermassive black hole at the centre of the Spiderweb Galaxy. The radio jets compress clouds of gas along their path and heat up water molecules contained within the clouds until they emit radiation.

    “Our results show how important it is to pinpoint the exact locations and origins for light in galaxies. We may also have new clues to the processes that trigger star formation in interstellar clouds,” said Gullberg. “Stars are born out of cold, dense molecular gas. The regions in the Spiderweb where we’ve detected water are currently too hot for stars to form. But the interaction with the radio jets changes the composition of the gas clouds. When the molecules have cooled down again, it will be possible for the seeds of new stars to form. These “dew drop” regions could become the next stellar nurseries in this massive, complex galaxy.”

    Further information

    ALMA Finds Dew Drops in the Dusty Spider’s Web, Bitten Gullberg et al, February 2016, Astronomy & Astrophysics: http://arxiv.org/pdf/1602.04823v1.pdf

    See the full article here .

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  • richardmitnick 9:23 am on July 1, 2016 Permalink | Reply
    Tags: , , Faint radio wave emissions in 'radio-quiet' quasars, , Radio Astronomy   

    From phys.org: “Gravitational lens zooms in on why some quasars have the radio turned down” 

    physdotorg
    phys.org

    July 1, 2016
    No writer credit found

    1
    Left: Reconstruction of the lensed radio-quiet quasar HS0810+2554 after removing the effects of the lensing. Right: the data from the Karl G. Jansky Very Large Array showing what the source looks like after passage through the lensing galaxy. The images are not to scale – the lensed image appears to be many times larger in the sky than the actual size of the source. Credit: N Jackson/NRAO

    Mini-jets of material ejected from a central supermassive black hole appear to be the culprits behind faint radio wave emissions in ‘radio-quiet’ quasars. A study of gravitationally lensed images of four radio-quiet quasars has revealed the structure of these distant galaxies in unprecedented detail. This has enabled astronomers to trace the radio emissions to a very small region at the heart of the quasars, and helped to solve a 50-year-old puzzle about their source. The results will be presented by Dr Neal Jackson at the National Astronomy Meeting in Nottingham on Friday, 1st July.

    “In radio-loud quasars, the intense radio emission clearly comes from vast jets of material blasted out from the region around a central black hole. By contrast, the radio emission from radio-quiet quasars is extremely feeble and difficult to see, so it has been hard to identify its source,” explained Jackson of the Jodrell Bank Centre for Astrophysics in Manchester. “To study most radio-quiet quasars, we will have to wait until future extremely large telescopes, like the Square Kilometre Array, come online. However, if we find radio-quiet quasars which are lensed by galaxies in front of them, we can use the increased brightness to be able to study them with today’s radio telescopes.”

    Gravitational lensing is a phenomenon where light from distant objects is warped by the gravitational field of massive objects in the foreground, a bit like light travelling through a glass lens. The mass distribution in a galaxy acts rather like a lens shaped like the bottom of a wineglass, and produces multiple images of background objects, with images stretched out into arcs and rings.

    2
    e-MERLIN picture of one of the lensed radio-quiet quasars, HS0810+2554. Credit: N Jackson/JCBA

    Jackson and colleagues used the Karl G. Jansky Very Large Array, in New Mexico, US, to study four examples of gravitational lens systems where the background quasar appears in a ring of four, distorted images.

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

    Two of the systems were also observed by the UK’s e-MERLIN array.

    eMerlin Radio Telecope Array
    eMerlin Radio Telecope Array, England

    After correcting for the distorting effects of the lens, the team were able to accurately measure the sizes of the radio-emitting regions in the sample of quasars.

    “The cause of radio emissions in radio-quiet quasars has been the subject of debate. One theory suggested that they were caused by multiple explosions of individual supernovae in the galaxy surrounding the quasar,” said Jackson. “These new observations have allowed us to narrow down the emissions to a very small region, typical of an active nucleus – i.e. jets emanating from a supermassive black hole. We are currently working on some further data that we hope will confirm our preliminary findings. If so, we can rule out the supernova explanation, which would show radio emissions from a much larger area, and confirm that the processes driving radio-quiet quasars are the same as their loud counterpart, just on a smaller scale.”

    4
    A montage of the Karl G. Jansky Very Large Array data for this object (greyscale) with Hubble Space Telescope data overlaid (contours). Credit: N Jackson/NRAO/NASA/ESA

    See the full article here .

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

     
  • richardmitnick 11:45 am on June 28, 2016 Permalink | Reply
    Tags: , , , , Radio Astronomy   

    From Nature: “Why ultra-powerful radio bursts are the most perplexing mystery in astronomy” 

    Nature Mag
    Nature

    28 June 2016
    Elizabeth Gibney

    1
    The Parkes telescope in Australia detected the first fast radio burst in 2001. Wayne England

    No astronomer had ever seen anything like it. No theorist had predicted it. Yet there it was — a 5-millisecond radio burst that had arrived on 24 August 2001 from an unknown source seemingly billions of light years away.

    “It was so bright, we couldn’t just dismiss it,” says Duncan Lorimer, who co-discovered the signal [1] in 2007 while working on archived data from the Parkes radio telescope in New South Wales, Australia. “But we didn’t really know what to do with it.”

    Such fleeting radio bursts usually came from pulsars — furiously rotating neutron stars whose radiation sweeps by Earth with the regularity of a lighthouse beam. But Lorimer, an astrophysicist at West Virginia University in Morgantown, saw this object erupt only once, and with more power than any known pulsar.

    He began to realize the significance of the discovery [1] only after carefully going over the data with his former adviser, Matthew Bailes, an astrophysicist at Swinburne University of Technology in Melbourne, Australia. If the source was really as far away as it seemed, it had released the energy of 500 million Suns in just a few milliseconds. “We became convinced it was something quite remarkable,” he says.

    But when no more bursts appeared, initial excitement turned to doubt. Radio astronomers have learnt to be sceptical of mysterious spikes in their detectors: the events can all too easily result from mobile-phone signals, stray radar probes, strange weather phenomena and instrumental glitches. Wider acceptance of what is now known as the Lorimer burst came only in the past few years, after observers working at Parkes and other telescopes spotted similar signals. Today, the 2001 event is recognized as the first in a new and exceedingly peculiar class of sources known as fast radio bursts (FRBs) — one of the most perplexing mysteries in astronomy.

    Whatever these objects are, recent observations suggest that they are common, with one flashing in the sky as often as every 10 seconds [2]. Yet they still defy explanation. Theorists have proposed sources such as evaporating black holes, colliding neutron stars and enormous magnetic eruptions. But even the best model fails to account for all the observations, says Edo Berger, an astronomer at Harvard University in Cambridge, Massachusetts, who describes the situation as “a lot of swirling confusion”.

    Clarity may come soon, however. Telescopes around the world are being adapted to look for the mysterious bursts. One of them, the Canadian Hydrogen Intensity Mapping Experiment (CHIME) near Penticton in British Columbia, should see as many as a dozen FRBs per day when it comes online by the end of 2017.

    3
    CHIME

    “This area is set to explode,” says Bailes.

    Curiouser and curiouser

    Astronomers might have had more confidence in the Lorimer burst initially had it not been for a discovery in 2010 by Sarah Burke-Spolaor, who was then finishing her astrophysics PhD at Swinburne. Burke-Spolaor, now an astronomer at the US National Radio Astronomy Observatory in Socorro, New Mexico, was trawling through old Parkes data in search of more bursts when she turned up 16 signals that shook everyone’s confidence in the original [3].

    In most ways, these signals looked remarkably similar to the Lorimer event. They, too, showed ‘dispersion’, meaning that high-frequency waves appeared in the detectors a few hundred milliseconds before the low-frequency ones. This dispersion effect was the most important piece of evidence convincing Lorimer and Bailes that the original burst came from well beyond our Galaxy. Interstellar electrons in clouds of ionized gas are known to interact more with low-frequency waves than with high-frequency ones, which delays the low-frequency waves’ arrival at Earth ever so slightly, and stretches the signal (see ‘Flight delays‘). The delay in the Lorimer burst was so extensive that the wave had to have travelled through a lot of matter — much more than is in our Galaxy.

    4
    Nik Spencer/Nature; Source: Fig. 1 In Keane, E. F. et al. Nature 530, 453–456 (2016)

    Unfortunately for Lorimer and Bailes’ peace of mind, Burke-Spolaor’s signals also showed a crucial difference from the original: they seemed to pour in from everywhere, not just from where the telescope was pointing. Dubbed perytons, after a mythical winged creature that casts a human shadow, these bursts could have been caused by lightning, or some human-made source. But they were not extraterrestrial.

    Lorimer decided to postpone his research into FRBs for a while. “I didn’t yet have tenure,” he says, “so I had to go back and do more mainstream projects, just to keep my research moving.” Bailes and his team kept going, and upgraded the Parkes detector’s time and frequency resolution. In 2013, they turned up four new FRB candidates that resembled the Lorimer burst [4]. But some outsiders remained sceptical that the signals were really coming from space — not least because all the FRBs thus far had been seen by one team using one telescope. “I was desperate for someone else to find them somewhere else,” says Bailes.

    In 2014, his wish was finally granted. A team led by astronomer Laura Spitler at the Max Planck Institute for Radio Astronomy in Bonn, Germany, published their observations of a burst at the Arecibo Observatory in Puerto Rico5. “I was ridiculously overjoyed,” says Bailes.

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

    The Arecibo discovery convinced most people that FRBs were the real deal, says Emily Petroff, who is now an astrophysicist at the Netherlands Institute for Radio Astronomy in Dwingeloo. Yet, as long as the Burke-Spolaor signals went unexplained, they cast a shadow of doubt. “At any talks I would give,” says Petroff, “someone would say, ‘But what about perytons?’” So in 2015, while still a graduate student at Swinburne, she led a hunt to track down the source of perytons once and for all.

    First, Petroff and her team used the upgraded Parkes detector to pinpoint when the bursts were happening: at lunchtime. “Immediately I thought, ‘This isn’t weather’,” says Petroff. Then came another peryton at a suspiciously familiar radio frequency, which led the team to run experiments in the staff kitchen. Perytons, they discovered, were the result of scientists opening the microwave oven mid-flow. But the Lorimer event was in the clear: records showed that at the time of the burst, the telescope had been pointed in a direction that would have blocked any microwave signal from the kitchen [6].

    “So then I worried, maybe they’ve just got a different brand of microwave at Arecibo,” says Bailes, whose team at Parkes had, by then, racked up 14 separate bursts. He did not relax completely until later in 2015, when a burst was spotted at a third facility — the Green Bank Telescope in West Virginia.

    NRAO/GBT radio telescope, West Virginia, USA
    NRAO/GBT radio telescope, West Virginia, USA

    That burst had another quality that supported an extraterrestrial origin: its waves were rotated in a spiral pattern — which results from passing through a magnetic field — and were scattered as if they had emerged from a dense medium. “There’s no way that’s a microwave oven,” Bailes told himself.

    Bursts of inspiration

    But that still leaves the question of what the FRBs actually are. The extreme brevity of the signal, just 5 milliseconds, implied that the source must be a compact object no more than a few hundred kilometres across — a stellar-mass black hole, perhaps, or a neutron star, the compact core left over by a supernova. And the fact that Earth-based telescopes can detect the FRBs at all means that this compact source somehow puts out an immense amount of energy. But that still leaves a long list of candidates, from merging black holes to flares on magnetars: rare neutron stars with fields hundreds of millions of billions of times stronger than the Sun’s.

    An important clue arrived earlier this year when Spitler’s team reported that at least one FRB source repeats: data from Arecibo revealed a flurry of bursts over two months, some spaced just minutes apart [7]. That behaviour has been confirmed by the Green Bank telescope, which detects signals in a different frequency band8. Until then, each of the observed FRBs had been a one-off event, which hinted at cataclysmic explosions, or collisions in which the sources were destroyed. But a repeating FRB implies the existence of a source that survives the pulse event, says Petroff. And for that reason, she says, “I would assume it would be something to do with a neutron star” — one of the few known objects that can emit a pulse without self-destructing.

    Spitler agrees. As an example, she points to the Crab nebula: the result of a supernova explosion that was observed from Earth in 1054 and left behind a rapidly spinning pulsar surrounded by glowing gas.

    Supernova remnant Crab nebula. NASA/ESA Hubble
    Supernova remnant Crab nebula. NASA/ESA Hubble

    The Crab pulsar occasionally releases extremely bright and narrow radio flares, Spitler says. And if this nebula were in a distant galaxy and hugely boosted in energy, its emissions would look like FRBs.

    If one source repeats, Spitler says, the simplest interpretation is that they all do, but that other telescopes haven’t been sensitive enough — or lucky enough — to see the additional signals. Yet others think that perhaps only some are repeating. “I wouldn’t be surprised if we end up with two or three populations,” says Petroff.
    A long way home

    Another crucial question is how far away the FRBs are. The 20 bursts seen so far seem to be scattered randomly around the sky rather than being concentrated in the plane of the Galaxy, which suggests that their sources lie beyond the borders of the Milky Way.

    And yet to Avi Loeb, a physicist at Harvard University, such vast distances imply an implausibly large energy output. “If you want the burst to repeat, you won’t be able to destroy the source — therefore, it cannot release too much energy,” he says. “That puts a limit on how far away you can put it.” Perhaps, he says, the FRB sources are neutron stars in our own Galaxy, and the dispersion is mostly the result of still unknown electron clouds that blanket them.

    But others suggest that such a dense cloud in the Galaxy should be visible in other wavelengths. At the California Institute of Technology (Caltech) in Pasadena, astrophysicist Shri Kulkarni has scoured data from several telescopes for a galactic source and turned up nothing [9]. Kulkarni, who directs Caltech’s optical observatories, initially argued for galactic FRBs, and even made a US$1,000 bet on it with astronomer Paul Groot of Radboud University Nijmegen in the Netherlands. Now, he finds the evidence for extragalactic FRBs to be overwhelming, and has agreed to settle the bet — grudgingly. “I think I will pay him in $1 bills,” he says.

    5
    The black-hole collision that reshaped physics

    Still, Kulkarni hasn’t ruled out the possibility that the FRB sources lie in galaxies that are perhaps a billion light years away, rather than many billions. Such a distance would still require at least some of the signal dispersion to come from electron clouds in the host galaxy, he says. But closer FRBs would not have to be so energetic. “It takes them from being amazingly exotic, to just exotic,” he says.

    The answer could mean a great deal to observers. If the FRB signals have travelled through local plasma clouds, they could give weather reports from neighbouring galaxies. But if they are truly cosmological — coming from halfway across the visible Universe — they could solve a long-standing cosmic mystery.

    For decades, astronomers have known from observations of the early Universe that the cosmos should contain more everyday matter — the kind made up of electrons, protons and neutrons — than exists in the visible stars and galaxies. They suspect that it lies in the cold intergalactic medium, where it is effectively invisible. But now, for the first time, the dispersion of the FRB signals could enable them to measure the medium’s density in any given direction. “Then, we have essentially a surgical device to do intergalactic tomography,” says Kulkarni.

    Rapid-fire detection

    First, however, astronomers have to find a lot more FRBs and pin down their locations. “Until then, we are stumbling in the dark,” says Berger.

    One way to accomplish that is to extract the FRBs from radio-telescope data in real time, so that scientists at other observatories can observe the bursts in multiple wavelengths. Since last year, the Parkes team has been doing this by boosting the observatory’s in-house computing power, and scientists at Arecibo hope to follow suit this year. In February, the strategy seemed to be paying off when an independent team followed up within two hours of an FRB’s detection at Parkes. The team tentatively pinpointed the burst to a specific galaxy almost 6 billion light years away. Further observations cast doubt on that interpretation. But even so, says Lorimer, the method is sound and may pay off in the future.

    Others observers are putting their hopes in new telescopes. In 2014, astrophysicist Victoria Kaspi at McGill University in Montreal, Canada, submitted a proposal to adapt CHIME, which was originally designed to map the expansion of the Universe in its early years. “It became clear very quickly that it would be a fantastic FRB instrument,” says Kaspi. Although dish telescopes such as Arecibo can be highly sensitive, they observe only a single, tiny patch of sky at a time. CHIME, by contrast, consists of four 100-metre-long half-pipes dotted with antennas that can monitor much bigger stretches of sky in long lines. After undergoing testing and debugging, CHIME should see its first FRBs sometime next year, says Kaspi, ultimately finding more than a dozen per day.

    In Hoskinstown, Australia, meanwhile, Bailes and his colleagues are refurbishing the 1960s-vintage Molonglo Observatory Synthesis Telescope, turning it into an FRB observatory with a single half-pipe 16 times longer than CHIME’s, although one-quarter as wide.

    Molonglo Observatory Synthesis Telescope (MOST)
    U Sidney Molonglo Observatory Synthesis Telescope (MOST), Hoskinstown, Australia

    The team has already found three as-yet-unpublished FRBs with the facility working at only about 20% of its final sensitivity, says Bailes.

    Another strategy for locating the FRB sources is to work with existing facilities such as the Very Large Array: an ‘interferometer’ that uses the time difference between signals from 27 radio telescopes spaced across 36 kilometres of grassland near Socorro, New Mexico, to create a single, high-resolution image.

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

    Sometime in the next year or so, says Lorimer, the array could detect an FRB and locate its home galaxy. “Ultimately, that could settle a lot of arguments and bets,” he says.

    Kulkarni, meanwhile, is leading two projects. The first uses ten 5-metre-wide dishes in an array that can see and locate only super-bright FRBs, but that makes up for its low sensitivity by peering at a huge swathe of sky. The second takes the principle to the extreme, using 2 antennas spaced at observatories 450 kilometres apart that will see only the very brightest FRBs, but that are able to examine half the sky at once. That would enable it to catch the rare FRBs that presumably exist within our own Galaxy, but whose extreme brightness existing telescopes are not designed to see. “Most facilities would just discount it as interference,” says Kulkarni.

    If FRBs do turn out to come from cosmological distances, says Loeb, their identification would be a major breakthrough, potentially unravelling a new class of source that could be used to probe the Universe’s missing matter. But then, he says, FRBs could also be something that no one has thought of yet: “Nature is much more imaginative than we are.”

    References

    1. Lorimer, D. R., Bailes, M., McLaughlin, M. A., Narkevic, D. J. & Crawford, F. Science 318, 777–780 (2007).

    2. Champion, D. J. et al. Mon. Not. R. Astron. Soc. Lett. 460, L30–L34 (2016).

    3. Burke-Spolaor, S., Bailes, M., Ekers, R., Macquart, J.-P. & Crawford, F. III Astrophys. J. 727, 18 (2011).

    4. Thornton, D. et al. Science 341, 53–56 (2013).

    5. Spitler, L. G. et al. Astrophys. J. 790, 101 (2014).

    6. Petroff, E. et al. Mon. Not. R. Astron. Soc. 451, 3933–3940 (2015).

    7. Spitler, L. G. et al. Nature 531, 202–205 (2016).

    8. Scholz, P. et al. Preprint at http://arxiv.org/abs/1603.08880 (2016).

    9. Kulkarni, S. R., Ofek, E. O. & Neill, J. D. Preprint at http://arxiv.org/abs/1511.09137 (2015).

    See the full article here .

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  • richardmitnick 7:06 pm on June 27, 2016 Permalink | Reply
    Tags: , , Clandestine Black Hole May Represent New Population, , Radio Astronomy   

    From Chandra: “VLA J2130+12: Clandestine Black Hole May Represent New Population” 

    NASA Chandra Banner
    NASA Chandra Telescope

    NASA Chandra

    6.27.16

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    Composite

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    X-ray

    3
    Optical
    X-ray: NASA/CXC/Univ. of Alberta/B.Tetarenko et al; Optical: NASA/STScI; Radio: NSF/AUI/NRAO/Curtin Univ./J. Miller-Jones
    Release Date June 27, 2016

    The true identity of an unusual source in the Milky Way galaxy has been revealed.

    This object contains a very quiet black hole, a few times the Sun’s mass, about 7,200 light years from Earth.

    This discovery implies that there could be many more black holes in the galaxy than previously accounted for.

    Chandra data show the source can only be giving off a very small amount of X-rays, an important clue to its true nature.

    Astronomers have identified the true nature of an unusual source in the Milky Way galaxy. As described in our latest press release, this discovery implies that there could be a much larger number of black holes in the Galaxy that have previously been unaccounted for.

    The result was made by combining data from many different telescopes that detect various forms of light, each providing key pieces of information. These telescopes included NASA’s Chandra X-ray Observatory, the Hubble Space Telescope, NSF’s Karl G. Jansky Very Large Array (VLA), Green Bank Telescope, Arecibo Observatory, and the European Very Long Baseline Interferometry Network.

    NASA/ESA Hubble Telescope
    NASA/ESA Hubble Telescope

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

    NRAO/GBT radio telescope, West Virginia
    NRAO/GBT radio telescope, West Virginia, USA

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

    European VLBI
    European VLBI

    The collaborative nature of this study is depicted in this multi-panel graphic. The large panel shows a composite Chandra and optical image of the globular cluster M15 located in our galaxy, where the X-ray data are purple and the optical data are red, green and blue. The source being studied here is bright in radio waves, as shown in the close-up VLA image, but the Chandra data reveal it can only be giving off a very small amount of X-rays.

    This new study indicates this source, called VLA J213002.08+120904 (VLA J2130+12 for short), contains a black hole a few times the mass of our Sun that is very slowly pulling in material from a companion star. At this paltry feeding rate, VLA J2130+12 was not previously flagged as a black hole since it lacks some of the telltale signs that black holes in binary systems typically display.

    Previously, most astronomers thought that VLA J2130+12 was probably a distant galaxy. Precise measurements from the radio telescopes showed that this source was actually well within our Galaxy and about five times closer to us than M15. Hubble data identified the companion star in VLA J2130+12 having only about one-tenth to one-fifth the mass of the Sun.

    The observed radio brightness and the limit on the X-ray brightness from Chandra allowed the researchers to rule out other possible interpretations, such as an ultra-cool dwarf star, a neutron star, or a white dwarf pulling material away from a companion star.

    Because this study only covered a very small patch of sky, the implication is that there should be many of these quiet black holes around the Milky Way. The estimates are that tens of thousands to millions of these black holes could exist within our Galaxy, about three to thousands of times as many as previous studies have suggested.

    A paper describing these results appeared in the Astrophysical Journal. The authors were Bailey Tetarenko (University of Alberta), Arash Bahramian (Alberta), Robin Aranson (Alberta), James Miller-Jones (International Center for Radio Astronomy Research), Serena Repetto (Technion), Craig Heinke (Alberta), Tom Maccarone (Texas Tech University), Laura Chomiuk (Michigan State Univsersity), Gregory Sivakoff (Alberta), Jay Strader (Michigan State), Franz Kirsten (ICRAR), and Wouter Vlemmings (Chalmers University of Technology).

    See the full article here .

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    NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

     
  • richardmitnick 1:05 pm on June 23, 2016 Permalink | Reply
    Tags: , , , , Radio Astronomy   

    From phys.org: “How CSIRO is turbocharging the world’s largest radio telescopes” 

    physdotorg
    phys.org

    June 23, 2016
    Douglas Bock, The Conversation

    1
    The 500-metre Aperture Spherical Telescope (FAST) is the largest single-dish radio telescope in the world. Credit: NAOC

    The world’s largest single-dish radio telescope, FAST (the Five hundred metre Aperture Spherical Telescope), is rapidly taking shape in China.

    At 500 metres in diameter, it would only just fit under the arch of the Sydney Harbour Bridge.

    To put this into astronomical perspective, the Parkes Radio Telescope has a diameter of 64 metres, with a collecting area – the amount of surface that the radio waves can bounce off – of 3,216 m2.

    CSIRO/Parkes Observatory
    CSIRO/Parkes Observatory

    FAST, on the other hand, has a collecting area of 196,000 m2, which is 61 times greater.

    Radio waves raining down from the cosmos will bounce off this huge dish and into a receiver overhead, which is being built by CSIRO.

    To stay scientifically competitive, telescopes must have the latest technology. The telescope you see – the giant steel dish – will probably look much the same for decades. But behind the scenes, generation after generation of new instruments will be installed to analyse the incoming radio waves.

    The continuous improvement of these instruments is what keeps a telescope current. The Parkes telescope, for instance, is now 10,000 times more sensitive than when it was first built due to improvements beyond the dish itself.

    Instruments for radio telescopes aren’t bought off the shelf. Each telescope is different, and instruments are custom-made for the one they’ll be used on.

    2
    The CSIRO-built multibeam instrument being installed on the Arecibo telescope. Credit: Graeme Carrad

    Tuning in to the universe

    Radio astronomy is also a technically demanding field. The receivers are so sensitive, that they could pick up a mobile phone on Mars. We can even time the rotation of pulsars to 11 decimal places. Astronomers push to record transient events down to timescales of nanoseconds.

    Technical capability and science goals evolve in tandem: astronomers ask for more than they have, pushing the engineering ever onward.

    In CSIRO, that conversation happened at close quarters, with scientists and engineers mingling in the same tea-room. This frequent contact led to innovation that could not have taken place if the engineers had been working to meet “blue sky” science goals developed far away.

    Telescope upgrades have been integrated with a strong research and development program. One we have kept going through the ups and downs of capital funding over the decades.

    The receiver we’re building for China’s FAST telescope has grown from work we started decades ago. Traditionally, a single-dish telescope such as Parkes sees only one spot – one pixel – on the sky at any one time, and pictures must be built up by repeated scanning.

    But we dramatically boosted its capabilities by developing a “multibeam” receiver that lets Parkes see several spots on the sky at once.

    This receiver turbocharged Parkes, letting us scan the sky in less than a tenth of the usual time. It led Parkes to discover fast radio bursts and hundreds of new galaxies hidden behind the Milky Way.

    4
    An Australian Square Kilometre Array Pathfinder (ASKAP) antenna with a phased-array feed. Credit: CSIRO

    For the receiver on China’s FAST telescope, we’re providing proven technology rather than the very cutting edge. But it’s going into a telescope that’s even better than our one at Parkes. FAST will also search for pulsars, look for radio signals from extra-solar planets, and measure hydrogen in our own galaxy and tens of thousands of others.

    Beyond FAST

    The newest technology to speed up telescopes is phased-array feeds, which allow us to electronically synthesise a multipixel image of the sky. These feeds can “ignore” radio signals from satellites that would otherwise blind our receivers. We’ve used this technology on the Australian SKA Pathfinder (ASKAP) in Western Australia.

    SKA ASKAP Phased Array
    SKA ASKAP Phased Array

    SKA ASKAP radio telescope
    SKA ASKAP radio telescope

    The phased-array feeds have already produced some superb early science during commissioning. There are more design improvements in the pipeline.

    Plus, in the last few months we’ve learned more about how to best use the feeds by running one on Parkes, ahead of installing it on the Effelsberg telescope in Germany.

    MPIFR/Effelsberg Radio Telescope, Germany
    MPIFR/Effelsberg Radio Telescope, Germany

    In just a few years, ASKAP’s home – the Murchison Radio-astronomy Observatory – will also house 130,000 low-frequency dipoles – essentially television antennas – of the international Square Kilometre Array (SKA).

    SKA Murchison Widefield Array
    SKA Murchison Widefield Array

    We’re working with ASTRON, the leading astronomy organisation in the Netherlands, to deliver the technology that will let these dipoles (which don’t physically move) “look” in different directions. This will be based on a system we developed for ASKAP.

    Radio astronomy is not a big industry, but its technologies are central ones in radio communication, as shown by the well-known example of WiFi, which was born from radio astronomy. Australia’s experience in this field is a clear example of how innovation happens in practice.

    See the full article here .

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    STEM Icon

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    About Phys.org in 100 Words

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

     
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