Tagged: Radio Astronomy Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 6:31 pm on August 24, 2015 Permalink | Reply
    Tags: , , Radio Astronomy,   

    From SKA: “The road to key science observations with the SKA kicks off in Stockholm” 

    SKA Square Kilometer Array

    SKA

    24 August 2015
    No Writer Credit

    This morning the first SKA Key Science Workshop kicked off in Stockholm, Sweden. Some 150 astronomers from 23 countries have travelled to attend the meeting, the first of a series of such workshops over the next three years to define large scale collaborative projects looking at some of the key scientific questions the SKA hopes to answer.

    “This week’s meeting in Stockholm is the start of an important process to establish the teams that will carry out some of the most exciting science we hope to conduct with the SKA.” explains Robert Braun, the SKA Science Director.

    “It’s about discussing what scientific objectives these teams should focus on, who should lead them and how we can maximise what we call commensality – how multiple teams can use and benefit from the same data to conduct important science”.

    Particularly, the meeting aims to start discussing the goals and composition of the major international teams that will carry out these key science observations in the first five years of operation of the telescope. During that period, around 50% of the telescope time is expected to be dedicated to these high-priority observations.

    Many major areas of astrophysics are covered in these key projects including, among others, cosmology and the study of dark matter and dark energy; the search for life in the Universe through the study of molecules in forming planetary systems and the search for potential radio signals from intelligent civilisations; looking back at the cosmic dawn – the first billion years – of the Universe and the apparition of the first stars to study the distribution of hydrogen; mapping the thousands of pulsars in our galaxy; looking for gravitational waves and monitoring the sun’s activity.

    Some of these are set to fundamentally change our understanding of the Universe, like the discovery of the accelerated expansion of the Universe did. “It’s my hope and belief that some of the young workshop participants sitting here today will be back in Stockholm in some years to receive a Nobel Prize” commented Swedish representative to the SKA Board and director of Onsala Space Observatory Prof. John Conway.

    Although there are more than 150 participants at this meeting, many more will be involved in establishing the SKA key science projects, engaged through future workshops, eventually leading to a call for expressions of interest around 2018. These will be reviewed by a international panel of experts and allocated based on scientific merit, technical feasibility, representation of member countries and potential to benefit other science (commensality) among other criteria.

    The meeting takes place in parallel to the publication of the SKA science book, a large two-volume collection of 135 refereed papers covering the main science observations to be carried out with the SKA.

    See the full article here.

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition

    SKA Banner

    SKA CSIRO  Pathfinder Telescope
    SKA ASKAP Pathefinder Telescope

    SKA Meerkat telescope
    SKA Meerkat Telescope

    SKA Murchison Widefield Array
    SKA Murchison Wide Field Array

    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.

     
  • richardmitnick 5:02 pm on August 22, 2015 Permalink | Reply
    Tags: , , , Radio Astronomy   

    From CSIRO: “Dwarf galaxies feel the blast from larger neighbours” 

    CSIRO bloc

    Commonwealth Scientific and Industrial Research Organisation

    August 22, 2015
    Megan Johnson, author

    1
    A composite image of Centaurus A which has a dwarf galaxy ESO 324-G024 nearby. X-ray: NASA/CXC/SAO; Optical: Rolf Olsen; Infrared: NASA/JPL-Caltech

    NASA Chandra Telescope
    NASA/Chandra

    NASA Spitzer Telescope
    NASA/Spitzer

    Dwarf galaxies are the most abundant galaxies in the universe. Yet understanding how these systems behave in galaxy group environments is still a mystery.

    These objects are notoriously difficult to study because they are very small relative to classic spiral galaxies. They also have low mass and a low surface brightness, which means that, to date, we have only studied the dwarf galaxies in the nearby universe, out to about 35 million light years away.

    My collaborators and I have been studying a dwarf galaxy named ESO 324-G024 and its connection to the northern radio lobe of a galaxy known as Centaurus A (Cen A) .

    3
    Centaurus A

    The giant radio lobes are comprised of high energy charged particles, mostly made up of protons and electrons, that are moving at extremely high speeds. The lobes were created from the relativistic jet (shown in the image at the top) that is blasting out of the central core of Cen A.

    2
    The giant radio lobes of Cen A. For scale, the entire image at the top of the article fits within the small black box shown here in the centre the two lobes. Megan Johnson, Author provided

    These energetic particles glow at radio frequencies and can be seen as the fuzzy yellow lobes in the centre of the image (above), together with the neutral hydrogen intensity (HI) maps of its companion galaxies. The lobes now occupy a volume more than 1,000 times that of the host galaxy shown in the image at the top, assuming the lobes are as deep as they are wide.

    These HI intensity maps are part of a large HI survey of nearby galaxies called the Local Volume HI Survey (LVHIS). These maps have been magnified in size by a factor of 10 so that they can be seen on such a large scale and are coloured by their relative distances to the centre of Cen A.

    A green galaxy is at virtually the same distance from Earth as Cen A, while blue galaxies are in front of Cen A (closer to us) and red galaxies are behind it (farther away).

    One of the striking things about this image is that out of the 17 galaxies overlaid onto the Cen A field, 14 are dwarf galaxies.

    An interesting dwarf

    The one object that really interested me after making this image was the dwarf irregular galaxy ESO 324-G024 (just above the black box). It has a long HI gaseous tail that extends roughly 6,500 light years to the northeast of its main body and it is at nearly the same distance as Cen A.

    These two pieces of information right away made this a system worthy of investigation because we thought that perhaps there is a connection between this dwarf galaxy and the northern radio lobe of Cen A.

    Nothing like this has ever been seen before, probably because galaxies that have giant radio lobes like Cen A are usually hundreds of millions to billions of light years away. Cen A is a special galaxy because it’s only about 12 million light years from Earth.

    From observations using the Parkes Radio Telescope and the Australian Telescope Compact Array we were able to conclude that ESO 324-G024 must actually be behind the northern radio lobe of Cen A.

    CSIRO Parkes Observatory
    CSIRO Parkes Observatory

    CSIRO Australia Compact Array
    CSIRO Australian Telescope Compact Array

    This was an interesting result and it told us that the northern radio lobe must be inclined toward our line of sight, because ESO 324-G024 was at nearly the same distance as Cen A. This had previously been suggested by studying the jet way down in the core of the host galaxy, but it had never been confirmed in this way before.

    A wind in the tail

    Next we investigated the mechanism responsible for creating the HI tail in ESO 324-G024. We looked at the likelihood of gravitational forces from the large, central host galaxy of Cen A as a potential culprit for ripping out ESO 324-G024’s gas. But we determined that it is simply too far away from the central gravitational potential for gravity to have created the tail.

    So we explored ram pressure stripping, which is thought to be a dominant force for removing gas in galaxies within these kinds of groups. Ram pressure is a force created when a galaxy moves through a dense medium, and thus experiences a wind in its “face”.

    3
    Here you can see the blue streak of gas and dust from spiral galaxy ESO 137-001 being stripped away by ram pressure as it hurtles through space. NASA, ESA, CXC

    NASA Hubble Telescope
    NASA/ESA Hubble

    It’s similar to holding a dandelion in your hand and then running as fast as you can go and watching the seeds blow away in the wind. At rest, the dandelion feels no wind and the seeds stay intact. But when you run, all of a sudden, the dandelion feels the wind created from your running and this wind blows away the seeds.

    In this scenario, ESO 324-G024 is the dandelion and you represent gravity carrying the galaxy through space. We calculated the wind speed required to blow the gas out of ESO 324-G024 and compared this speed to the speed of ESO 324-G024 moving through space. It turns out that the two speeds did not match.

    ESO 324-G024 seemed to be moving too slow for all of its gas to have been blown into its long tail. So we went back to our first conclusion about ESO 324-G024 being behind the radio lobe and surmised what may be happening.

    Strong winds

    We know that the charged particles inside the northern radio lobe of Cen A are moving extremely fast. If ESO 324-G024 is just now coming into contact with the posterior outer edge of the radio lobe of Cen A, which is likely due to its proximity to Cen A, then it is possible that ESO 324-G024 is not only feeling the wind generated from its own motion through space, but also the wind from the charged particles in the radio lobe itself.

    This would be like you running with the dandelion and at the same time blowing on it. Therefore, we concluded that ESO 324-G024 is most likely experiencing ram pressure stripping of its gas as it passes close to the posterior edge of the northern radio lobe.

    This means that these types of radio lobes must have wreaked havoc on their dwarf galaxy companions in the distant past. This is an interesting case study that showcases how dwarf galaxies may have been knocked about, blasted, by their larger companion galaxies.

    Just how common are situations like this and how have they influenced dwarf galaxies over cosmic time? The answer is that we simply don’t know, but I look forward to exploring these questions.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    CSIRO campus

    CSIRO, the Commonwealth Scientific and Industrial Research Organisation, is Australia’s national science agency and one of the largest and most diverse research agencies in the world.

     
  • richardmitnick 1:29 pm on August 21, 2015 Permalink | Reply
    Tags: , , , , Radio Astronomy   

    From ALMA: “ALMA teaches its operating software to future engineers at UFRO” 

    ESO ALMA Array
    ALMA

    14 August 2015
    Valeria Foncea
    Education and Public Outreach Officer
    Joint ALMA Observatory
    Santiago, Chile
    Tel: +56 2 467 6258
    Cell: +56 9 75871963
    Email: vfoncea@alma.cl

    1

    Moving an ALMA antenna or monitoring its alarm system are just a few of the many tasks carried out as a result of applications developed using a single technological infrastructure known as ALMA Common Software (ACS). In use for more than 15 years, this is an open-source platform that contains all of the observatory’s libraries, functions and services and has already been used by other astronomical projects.

    Temp 1
    With the mission of training future astro software engineers, ALMA experts visited the southern Chilean city of Temuco to present a series of talks and give a 3-day workshop to students on different career paths at the School of Engineering and Science of Universidad de La Frontera (UFRO).

    “The ACS platform is a tool that has evolved over time, and these workshops – now in its 12th edition – have helped to generate a global community of developers who have contributed to making it even better,” indicates Jorge Ibsen, Head of ALMA’s Computer Department. “These workshops enrich the professional education of their participants, who in many cases have ended up working on astronomical projects.”

    The ALMA Common Software (ACS) workshops began in 2004, when construction of the largest radio telescope in the world in northern Chile was underway. Since then, workshops have been held in many different institutions and universities around the world, some of them Chilean, but this is the first workshop held in southern Chile. This is the outcome of a memorandum of understanding signed last year between ALMA and UFRO (see article).

    3
    “This memorandum and the knowledge transfer between ALMA professionals and researchers at Universidad de La Frontera has resulted in new lines of research in the field of Astro-engineering, Science and Technology,” says the Dean of the School of Engineering and Science, Cristian Bornhardt. “With the joint development of this type of activity, we are able to offer new and valuable opportunities to support our students’ education in areas that are of utmost importance to the country’s strategic development.”

    This workshop addressed the main characteristics, functions and potential offered by this software infrastructure especially designed to monitor and control the radio telescope. It included the implementation of a toy model of what the observatory does using ACS.

    4
    “The impact of the observatories installed in Chile goes beyond astronomy; it permeates the engineering needed for day-to-day operations,” says Jorge Ibsen, who led the talks and workshops in conjunction with Tzu-Chiang Shen and Rubén Soto, ALMA software group managers, and Arturo Hoffstadt, ALMA software engineer.

    5

    To facilitate the implementation of educational activities and software development in the area of astro-engineering, ALMA donated 10 servers to the School of Engineering and Sciences at Universidad de la Frontera.

    See the full article here.

    Please help promote STEM in your local schools.
    STEM Icon
    Stem Education Coalition

    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 6:45 am on August 18, 2015 Permalink | Reply
    Tags: , , , Radio Astronomy,   

    From ICRAR: “Carole Jackson – Radio Astronomer, SKA Expert” 

    International Center for Radio Astronomy Research

    International Centre for Radio Astronomy Research

    18 Aug 2015

    1
    Carole Jackson

    After 18 years involvement with the development of the multi-billion dollar telescope, there’s not much Professor Carole Jackson does not know about the Square Kilometre Array.

    SKA Square Kilometer Array

    Carole was lured to Perth in 2013 with the award of a prestigious WA Fellowship and has made a strong addition to the ICRAR leadership team.

    She brings more than 25 years experience in both industry and research, and has particular interests in radio-loud active galactic nuclei, technology development and industry partnerships.

    Prior to joining ICRAR, Carole spent 10 years at csiro, where she led the design and commissioning of the 36 dish antennas that make up the Australian SKA Pathfinder (ASKAP).

    SKA CSIRO  Pathfinder Telescope
    SKA ASKAP Pathfinder Telescope

    She led the formation of the international SKA Dish Consortium, a group comprising members from South Africa, the UK, China, Canada, Italy and Sweden, including a number of major industry partners.

    Carole says the most exciting aspect of moving to ICRAR has been the opportunity to rekindle her own astronomical research, applying her expertise in the evolution of active galactic nuclei to observations flowing from telescopes such as the Murchison Widefield Array.

    “ Over the next few years there’s going to be a wealth of new results from these new low frequency surveys.”
    Carole loves the discovery aspect of her work, obtaining insights into the workings of the Universe such as how galaxies that were once so powerful seem to have faded away.

    “The other side I see is how you can build big groups, and watch those teams really producing great work,” she says.

    “It is all about recruiting the right people and then allowing them to go do what they’re really good at.”

    See the full article here.

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition

    ICRAR is an equal joint venture between Curtin University and The University of Western Australia with funding support from the State Government of Western Australia. The Centre’s headquarters are located at UWA, with research nodes at both UWA and the Curtin Institute for Radio Astronomy (CIRA).
    ICRAR has strong support from the government of Australia and is working closely with industry and the astronomy community, including CSIRO and the Australian Telescope National Facility, iVEC, and the international SKA Project Office (SPO), based in the UK.

    ICRAR is:

    Playing a key role in the international Square Kilometre Array (SKA) project, the world’s biggest ground-based telescope array.

    SKA Square Kilometer Array
    Attracting some of the world’s leading researchers in radio astronomy, who will also contribute to national and international scientific and technical programs for SKA and ASKAP.
    Creating a collaborative environment for scientists and engineers to engage and work with industry to produce studies, prototypes and systems linked to the overall scientific success of the SKA, MWA and ASKAP.

    SKA Murchison Widefield Array
    A Small part of the Murchison Widefield Array

    Enhancing Australia’s position in the international SKA program by contributing to the development process for the SKA in scientific, technological and operational areas.
    Promoting scientific, technical, commercial and educational opportunities through public outreach, educational material, training students and collaborative developments with national and international educational organisations.
    Establishing and maintaining a pool of emerging and top-level scientists and technologists in the disciplines related to radio astronomy through appointments and training.
    Making world-class contributions to SKA science, with emphasis on the signature science themes associated with surveys for neutral hydrogen and variable (transient) radio sources.
    Making world-class contributions to SKA capability with respect to developments in the areas of Data Intensive Science and support for the Murchison Radio-astronomy Observatory.

     
  • richardmitnick 11:56 am on August 9, 2015 Permalink | Reply
    Tags: , , Eliiptical Galaxies, Radio Astronomy,   

    From Yale: “Sorting through thickets of stars in elliptical galaxies far, far away” 

    Yale University bloc

    Yale University

    August 6, 2015
    Jim Shelton

    1
    Five views of the Hydra Galaxy Cluster — a full composite image, a look at the hot atmosphere of plasma that pervades the cluster, an ultraviolet image of young stars swirling, an optical image of the elliptical galaxy at the heart of the cluster, and a radio image of jets of relativistic plasma. (Images courtesy of the Hubble Space Telescope, Chandra X-ray Observatory, and the Jansky Very Large Array)

    NASA Hubble Telescope
    NASA/ESA Hubble

    NASA Chandra Telescope
    NASA/Chandra

    NRAO VLA
    NRAO/VLA

    A Yale University astronomer has helped untangle the cosmic knots of stars at the center of giant, elliptical galaxies.

    Two studies, one led by Yale’s Grant Tremblay and other led by Michigan State University researcher Megan Donahue, are providing new information about why the universe’s largest elliptical galaxies ratchet down their star production despite having plenty of available star-making material. Tremblay’s paper appeared in the Monthly Notices of the Royal Astronomical Society; Donahue’s paper appeared in the Astrophysical Journal.

    Elliptical galaxies, named for their elliptical shape, are the most common galaxies in the universe. In some of the largest elliptical galaxies, stars continue to develop along the jets of active black holes — but only at a moderate rate.

    Using data collected by space telescopes, including the Hubble, and from observatories on the ground, the researchers detect a self-regulating cycle of star births within elliptical galaxies. Jets shooting out of a galaxy’s center control the rate at which surrounding gas cools and falls into the galaxy, almost like raindrops.

    “The ‘raindrops’ eventually cool enough to become star-forming clouds of cold molecular gas, and the unique, far ultraviolet capabilities of Hubble allowed us to directly observe these ‘showers’ of star formation,” said Tremblay, who is a NASA Einstein Fellow at Yale. “We know that these showers are linked to the jets because they’re found in filaments and tendrils that wrap around the jets or hug the edges of giant bubbles that the jets have inflated, and they end up making a swirling ‘puddle’ of star-forming gas around the central black hole.”

    Tremblay’s work focused on elliptical galaxies in the nearby universe, while Donahue’s team looked at galaxies in the more distant universe. Their results indicate that galactic collisions and other extreme cosmic events are not always necessary for the creation of showers of new stars.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Yale University Campus

    Yale University comprises three major academic components: Yale College (the undergraduate program), the Graduate School of Arts and Sciences, and the professional schools. In addition, Yale encompasses a wide array of centers and programs, libraries, museums, and administrative support offices. Approximately 11,250 students attend Yale.

     
  • richardmitnick 7:59 am on August 4, 2015 Permalink | Reply
    Tags: , , , Flash Project, Radio Astronomy,   

    From CAASTRO: “Pilot study data prepare astronomers for future blind HI surveys” 

    CAASTRO bloc

    CAASTRO ARC Centre of Excellence for All Sky Astrophysics

    1

    4 Aug 2015

    Next-generation radio telescopes will make it possible to conduct the first large-scale HI absorption-line surveys, which will enable us to study the evolution of neutral gas in galaxies over a large range of cosmic time. However, we don’t currently have the understanding to derive physical galaxy properties from absorption-line data alone.

    To gain this understanding, we need to start by knowing the expected detection rate of intervening HI absorption. Previous studies have suggested that the detection rate is around 50% for sightlines bypassing the galaxy at distances of 20 kpc or less. However, these studies have typically targeted sightlines to quasars which provide very bright, compact radio sources ideal for detecting HI absorption against. Since only around 10% of all radio sources are quasars, it is therefore possible that such studies will have over-estimated the detection rate, compared to what future blind surveys might expect to find.

    In a new study, CAASTRO researcher Sarah Reeves (University of Sydney) and colleagues have investigated the detection rate of intervening absorption in an unbiased sample of radio sources. Importantly, they also obtained HI emission-line data, allowing them to map the distribution of HI gas in the target galaxies. This means that where they did not detect an absorption-line, they were able to pin-point the reason for the non-detection, i.e. whether the lack of absorption was due to the sightline not intersecting the HI disk of the galaxy or due to the properties of the background radio source (e.g. too dim) – or some other reason.

    This publication presents observations and results from the pilot sample (six of an eventual 16 sources). In this pilot sample, no intervening absorption-lines were detected. While observations for the full sample are required to better establish the detection rate, this preliminary result suggests that the detection rate is considerably lower than estimated by previous studies – perhaps around 5-10%. The team found that most of their sightlines did intersect the HI disk of the target galaxies, meaning that the low detection rate must be due to properties of the background sources. They found that many of the background sources resolved into multiple components at higher resolution, lowering the flux and reducing the absorption-line sensitivity. These results show that source type and structure can significantly affect the detection rate of absorption-line surveys, and help astronomers to better prepare for future large surveys, such as FLASH (‘The First Large Absorption Survey in HI’).

    Publication details:
    S. N. Reeves, E. M. Sadler, J. R. Allison, B. S. Koribalski, S. J. Curran, and M. B. Pracy in MNRAS (2015) HI emission and absorption in nearby, gas-rich galaxies

    FLASH

    The First Large Absorption Survey in HI (FLASH) is a wide-field ASKAP survey that will provide world-class science through the provision of new measurements of the amount and distribution of HI in distant galaxies, allowing us for the first time to investigate the relationship between HI gas supply and star formation rate in individual galaxies at z>0.5.

    SKA Pathfinder Radio Telescope
    SKA ASKAP telescopes

    ASKAP will be an array of 36 antennas each 12m in diameter, capable of high dynamic range imaging and using wide-field-of-view phased array feeds. ASKAP is intended to be a world-class telescope in its own right as well as a pathfinder instrument for the Square Kilometre Array.

    ASKAP’s large spectral bandwidth (300 MHz bandwidth over the frequency range 700-1800 MHz) and wide field of view (30 square degrees) will open up a completely new parameter space for large, blind HI absorption-line surveys using background radio continuum sources. Since the detection limit for such surveys is independent of redshift, ASKAP-FLASH will allow us to learn about the neutral gas content of galaxies in the poorly-explored redshift range 0.5 < z < 1.0, where the HI emission line is too weak to be detectable in even the deepest ASKAP surveys. The FLASH survey aims to detect and measure several hundred HI absorption lines (from both intervening and associated absorbers). This will provide a unique dataset for studies of galaxy evolution as well as a new estimate of the HI mass density at intermediate redshifts. The FLASH data will also be used for HI emission-line stacking experiments in combination with large-area optical redshift surveys like WiggleZ and GAMA.

    2
    Professor Elaine Sadler (Project Leader)

    CAASTRO Member Node
    Professor Lister Staveley-Smith University of Western Australia
    Associate Professor Martin Meyer University of Western Australia
    Dr. James Allison University of Sydney
    Dr. Stephen Curran University of Sydney
    Ms. Sarah Reeves University of Sydney
    Mr. Marcin Glowacki University of Sydney
    Associate Professor Chris Blake Swinburne University
    Professor Matthew Colless Australian National University

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Astronomy is entering a golden age, in which we seek to understand the complete evolution of the Universe and its constituents. But the key unsolved questions in astronomy demand entirely new approaches that require enormous data sets covering the entire sky.

    In the last few years, Australia has invested more than $400 million both in innovative wide-field telescopes and in the powerful computers needed to process the resulting torrents of data. Using these new tools, Australia now has the chance to establish itself at the vanguard of the upcoming information revolution centred on all-sky astrophysics.

    CAASTRO has assembled the world-class team who will now lead the flagship scientific experiments on these new wide-field facilities. We will deliver transformational new science by bringing together unique expertise in radio astronomy, optical astronomy, theoretical astrophysics and computation and by coupling all these capabilities to the powerful technology in which Australia has recently invested.

    PARTNER LINKS

    The University of Sydney
    The University of Western Australia
    The University of Melbourne
    Swinburne University of Technology
    The Australian National University
    Curtin University
    University of Queensland

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

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

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

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

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

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

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

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

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

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

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

    NRAO VLA
    VLA

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

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

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

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

    ALMA Array

    NRAO ALMA

    NRAO GBT
    NRAO GBT

    NRAO VLA
    NRAO VLA

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

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

     
  • richardmitnick 10:27 am on July 29, 2015 Permalink | Reply
    Tags: , , , Radio Astronomy,   

    From isgtw: “Supercomputers listen for extraterrestrial life” 


    international science grid this week

    July 29, 2015
    Lance Farrell

    Last week, NASA’s New Horizons spacecraft thrilled us with images from its close encounter with Pluto.

    NASA New Horizons spacecraft II
    NASA/New Horizons

    New Horizons now heads into the Kuiper belt and to points spaceward. Will it find life?


    Known objects in the Kuiper belt beyond the orbit of Neptune (scale in AU; epoch as of January 2015).

    That’s the question motivating Aline Vidotto, scientific collaborator at the Observatoire de Genève in Switzerland. Her recent study harnesses supercomputers to find out how to tune our radio dials to listen in on other planets.

    1
    Model of an interplanetary medium. Stellar winds stream from the star and interact with the magnetosphere of the hot-Jupiters. Courtesy Vidotto

    Vidotto has been studying interstellar environments for a while now, focusing on the interplanetary atmosphere surrounding so-called hot-Jupiter exoplanets since 2009. Similar in size to our Jupiter, these exoplanets orbit their star up to 20 times as closely as Earth orbits the sun, and are considered ‘hot’ due to the extra irradiation they receive.

    Every star generates a stellar wind, and the characteristics of this wind depend on the star from which it originates. The speed of its rotation, its magnetism, its gravity, or how active it is are among the factors affecting this wind. These variables also modify the effect this wind will have on planets in its path.

    Since the winds of different star systems are likely to be very different from our own, we need computers to help us boldly go where no one has ever gone before. “Observationally, we know very little about the winds and the interplanetary space of other stars,” Vidotto says. “This is why we need models and numerical simulations.”

    Vidotto’s research focuses on planets four to nine times closer to their host star than Mercury is to the sun. She takes observations of the magnetic fields around five stars from astronomers at the Canada-France-Hawaii Telescope (CFHT) in Hawaii and the Bernard-Lyot Telescope in France and feeds them into 3D simulations. For her most recent study, she divided the computational load between the Darwin cluster (part of the DiRAC network) at the University of Cambridge (UK) and the Piz Daint at the Swiss National Supercomputing Center.

    Canada-France-Hawaii Telescope
    CFHT nterior
    CFHT

    Bernard Lyot telescope
    Bernard Lyot telescope interior
    Bernard Lyot

    The Darwin cluster consists of 9,728 cores, with a theoretical peak in excess of 202 teraFLOPS. Piz Daint consists of 5,272 compute nodes with 32 GB of RAM per node, and is capable of 7.8 petaFLOPS — that’s more computation in a day than a typical laptop could manage in a millennium.

    Vidotto’s analysis of the DiRAC simulations reveals a much different interplanetary medium than in our home solar system, with an overall interplanetary magnetic field 100 times larger than ours, and stellar wind pressures at the point of orbit in excess of 10,000 times ours.

    This immense pressure means these planets must have a very strong magnetic shield (magnetosphere) or their atmospheres would be blown away by the stellar wind, as we suspect happened on Mars. A planet’s atmosphere is thought to be initimately related to its habitability.

    A planet’s magnetism can also tell us something about the interior properties of the planet such as its thermal state, composition, and dynamics. But since the actual magnetic fields of these exoplanets have not been observed, Vidotto is pursuing a simple hypothesis: What if they were similar to our own Jupiter?

    Temp 1
    A model of an exoplanet magnetosphere interacting with an interstellar wind. Knowing the characteristics of the interplanetary medium and the flux of the exoplanet radio emissions in this medium can help us tune our best telescopes to listen for distant signs of life. Courtesy Vidotto.

    If this were the case, then the magnetosphere around these planets would extend five times the radius of the planet (Earth’s magnetosphere extends 10-15 times). Where it mingles with the onrushing stellar winds, it creates the effect familiar to us as an aurora display. Indeed, Vidotto’s research reveals the auroral power in these exoplanets is more impressive than Jupiter’s. “If we were ever to live on one of these planets, the aurorae would be a fantastic show to watch!” she says.

    Knowing this auroral power enables astronomers to realistically characterize the interplanetary medium around the exoplanets, as well as the auroral ovals through which cosmic and stellar particles can penetrate the exoplanet atmosphere. This helps astronomers correctly estimate the flux of exoplanet radio emissions and how sensitive equipment on Earth would have to be to detect them. In short, knowing how to listen is a big step toward hearing.

    Radio emissions from these hot-Jupiters would present a challenge to our current class of radio telescopes, such as the Low Frequency Array for radio astronomy (LOFAR). However, “there is one radio array that is currently being designed where these radio fluxes could be detected — the Square Kilometre Array (SKA),” Vidotto says. The SKA is set for completion in 2023, and in the DiRAC clusters Vidotto finds some of the few supercomputers in the world capable of testing correlation software solutions.

    Lofar radio telescope

    While there’s much more work ahead of us, Vidotto’s research presents a significant advance in radio astronomy and is helping refine our ability to detect signals from beyond. With her 3D exoplanet simulations, the DiRAC computation power, and the ears of SKA, it may not be long before we’re able to hear radio signals from distant worlds.

    Stay tuned!

    See the full article here.

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition

    iSGTW is an international weekly online publication that covers distributed computing and the research it enables.

    “We report on all aspects of distributed computing technology, such as grids and clouds. We also regularly feature articles on distributed computing-enabled research in a large variety of disciplines, including physics, biology, sociology, earth sciences, archaeology, medicine, disaster management, crime, and art. (Note that we do not cover stories that are purely about commercial technology.)

    In its current incarnation, iSGTW is also an online destination where you can host a profile and blog, and find and disseminate announcements and information about events, deadlines, and jobs. In the near future it will also be a place where you can network with colleagues.

    You can read iSGTW via our homepage, RSS, or email. For the complete iSGTW experience, sign up for an account or log in with OpenID and manage your email subscription from your account preferences. If you do not wish to access the website’s features, you can just subscribe to the weekly email.”

     
  • richardmitnick 8:43 am on July 29, 2015 Permalink | Reply
    Tags: , , CHIME experiment, , Radio Astronomy   

    From Nature: “‘Half-pipe’ telescope will probe dark energy in teen Universe” 

    Nature Mag
    Nature

    29 July 2015
    Davide Castelvecchi

    1
    The CHIME telescope array will search for a particular kind of hydrogen emission from ancient galaxies.

    It sounds almost too apt to be true. An observatory shaped like the half-pipes used by snowboarders, and dependent on technology originally designed for gaming and mobile phones, will soon be tasked with plugging a crucial gap in the cosmological record: what the Universe did when it was a teenager.

    The information will allow cosmologists to gauge whether the strength of dark energy — the force accelerating the Universe’s expansion — has changed over time, an unresolved question that governs the fate of the cosmos.

    Whereas typical radio telescopes have round dishes, the Canadian Hydrogen Intensity Mapping Experiment (CHIME) comprises four 100-metre-long, semi-cylindrical antennas, which lie near the town of Penticton in British Columbia.

    From 2016, CHIME’s half-pipes, which are scheduled to be completed this week, will detect radio waves emitted by hydrogen in distant galaxies. These observations would be the first measurements of the Universe’s expansion rate between 10 billion and 8 billion years ago, a period in which the cosmos went “from being a kid to an adult”, says Mark Halpern, the leader of CHIME and an experimental cosmologist at the University of British Columbia in Vancouver (see ‘Unveiling the adolescent Universe’). Straight after the Big Bang 13.8 billion years ago, the rate of the Universe’s expansion slowed. But somewhere during the ‘adolescent’ period, dark energy — which eventually turned the Universe’s slowing expansion into the acceleration observed today — began to be felt, he says.

    2

    It is a window in time that has, until now, been closed. Cosmologists measure the Universe’s past expansion rate using ancient objects, such as supernova explosions and the voids between galaxies, that are so distant that their light is only now reaching Earth. Over the past few decades, such objects have revealed that the cosmos has been expanding at an accelerating rate for more than 6 billion years. And surveys of quasars — mysterious, super-bright objects that outshine the entire galaxies they lie in — have shown that until 10 billion years or so ago, the Universe’s expansion was slowing down.

    But cosmologists have struggled to measure the expansion rate in the interim, leaving open the question of whether the strength of dark energy’s repulsive force may have varied over time.

    CHIME is designed to fill the gap, says Kendrick Smith, an astrophysicist at the Perimeter Institute for Theoretical Physics in Waterloo, Canada, who will work on analysing CHIME’s data. The half-pipe antennas will allow CHIME to receive radio waves coming from anywhere along a narrow, straight region of the sky at any given time. “As the Earth rotates, this straight shape sweeps out the sky,” says Smith.

    To sort out where individual signals are coming from, a custom-built supercomputer made of 1,000 relatively cheap graphics-processing units — the type used for high-end computer gaming — will crunch through nearly 1 terabyte of data per second. The team will also use signal amplifiers originally developed for mobile phones. Without such powerful consumer-electronics components, CHIME would have been prohibitively expensive, says experimental cosmologist Keith Vanderlinde of the University of Toronto, Canada, who is co-leading the project.

    CHIME’s supercomputer will look specifically for radio waves with a wavelength that suggests an age of 11 billion to 7 billion years, emitted by the hydrogen in the interstellar space inside galaxies (at their source, such emissions have a wavelength of 21 centimetres). Researchers will then subtract the ‘radio noise’ in the same wavelength range that comes from the Milky Way and Earth.

    Although CHIME will not be able to distinguish individual galaxies in this way, clumps of hundreds or thousands of galaxies will show up, says Vanderlinde. This will allow researchers to map the expansion rate of the voids between the clumps, and in turn to calculate the strength of dark energy during that time.

    If the results imply that the strength of dark energy then was the same as it has been in the past 6 billion years, it could suggest that galaxies will eventually lose sight of each other. But if the strength of dark energy has changed over the eons, all bets are off: the Universe could collapse in a ‘big crunch’, for example, or be ripped apart into its subatomic components.

    As well as mapping the adolescent Universe, CHIME could also detect hundreds of the mysterious ‘fast radio bursts’ that last just milliseconds and have no known astrophysical explanation. And it will help other experiments to calibrate measurements of radio waves from rapidly spinning neutron stars, which researchers hope to use to detect the ripples in space-time known as gravitational waves (see Nature 463, 147; 2010).

    CHIME is part of a growing trend in astronomy. A number of experiments that are now active or in the planning stages, including the hotly anticipated Square Kilometer Array — to be built on sites in Australia and South Africa — are designed to look at hydrogen emissions with 21-centimetre wavelengths. These emissions are an untapped trove of cosmological information, says Tzu-Ching Chang, an astrophysicist at the Academia Sinica Institute of Astronomy and Astrophysics in Taipei who helped to pioneer the hydrogen mapping of galaxies in a 2010 study (T.-Z. Chang et al. Nature 466, 463–465; 2010). She likens the boom in hydrogen mapping today to the trend in the 1990s of studying the relic radiation of the Big Bang, which revolutionized cosmology.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Nature is a weekly international journal publishing the finest peer-reviewed research in all fields of science and technology on the basis of its originality, importance, interdisciplinary interest, timeliness, accessibility, elegance and surprising conclusions. Nature also provides rapid, authoritative, insightful and arresting news and interpretation of topical and coming trends affecting science, scientists and the wider public.

     
  • richardmitnick 8:21 pm on July 27, 2015 Permalink | Reply
    Tags: , , , Radio Astronomy   

    From NRAO: “Brown Dwarfs, Stars Share Formation Process, New Study Indicates” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

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

    1
    Artist’s conception of a very young, still-forming brown dwarf, with a disk of material orbiting it, and jets of material ejected outward from the poles of the disk. CREDIT: Bill Saxton, NRAO/AUI/NSF

    Astronomers using the Karl G. Jansky Very Large Array (VLA) have discovered jets of material ejected by still-forming young brown dwarfs.

    NRAO VLA
    NRAO/VLA

    The discovery is the first direct evidence that brown dwarfs, intermediate in mass between stars and planets, are produced by a scaled-down version of the same process that produces stars.

    The astronomers studied a sample of still-forming brown dwarfs in a star-forming region some 450 light-years from Earth in the constellation Taurus, and found that four of them have the type of jets emitted by more-massive stars during their formation. The jets were detected by radio observations with the VLA. The scientists also observed the brown dwarfs with the Spitzer and Herschel space telescopes to confirm their status as very young objects.

    NASA Spitzer Telescope
    NASA/Spitzer

    ESA Herschel
    ESA/Herschel

    “This is the first time that such jets have been found coming from brown dwarfs at such an early stage of their formation, and shows that they form in a way similar to that of stars,” said Oscar Morata, of the Institute of Astronomy and Astrophysics of the Academia Sinica in Taiwan. “These are the lowest-mass objects that seem to form the same way as stars,” he added.

    Brown dwarfs are less massive than stars, but more massive than giant planets such as Jupiter. They have insufficient mass to produce the temperatures and pressures at their cores necessary to trigger the thermonuclear reactions that power “normal” stars. Theorists suggested in the 1960s that such objects should exist, but the first unambiguous discovery of one did not come until 1994.

    A key question has been whether brown dwarfs form like stars or like planets. Stars form when a giant cloud of gas and dust in interstellar space collapses gravitationally, accumulating mass. A disk of orbiting material forms around the young star, and eventually planets form from the material in that disk. In the early stages of star formation, jets of material are propelled outward from the poles of the disk. No such jets mark planet formation, however.

    Previous evidence strongly suggested that brown dwarfs shared the same formation mechanism as their larger siblings, but detecting the telltale jets is an important confirmation. Based on this discovery, “We conclude that the formation of brown dwarfs is a scaled-down version of the process that forms larger stars,” Morata said.

    Morata led an international team of astronomers with members from Asia, Europe, and Latin America. They reported their findings in the Astrophysical Journal.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

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

    ALMA Array

    NRAO ALMA

    NRAO GBT
    NRAO GBT

    NRAO VLA
    NRAO VLA

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

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

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
Follow

Get every new post delivered to your Inbox.

Join 462 other followers

%d bloggers like this: